- Add context lines

- Add strict udiff output format

TODO.txt

+- Docs

composer.json

 {
     "name": "sebastian/diff",
     "description": "Diff implementation",
-    "keywords": ["diff"],
+    "keywords": ["diff", "udiff", "unidiff", "unified diff"],
     "homepage": "https://github.com/sebastianbergmann/diff",
     "license": "BSD-3-Clause",
     "authors": [
@@ -18,7 +18,8 @@
         "php": "^7.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^6.2"
+        "phpunit/phpunit": "^6.2",
+        "symfony/process": "^3.3"
     },
     "autoload": {
         "classmap": [

src/Differ.php

@@ -10,7 +10,6 @@
 
 namespace SebastianBergmann\Diff;
 
-use SebastianBergmann\Diff\InvalidArgumentException;
 use SebastianBergmann\Diff\Output\DiffOutputBuilderInterface;
 use SebastianBergmann\Diff\Output\UnifiedDiffOutputBuilder;
 

src/Exception/ConfigurationException.php

+<?php declare(strict_types=1);
+/*
+ * This file is part of sebastian/diff.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace SebastianBergmann\Diff;
+
+final class ConfigurationException extends InvalidArgumentException
+{
+    /**
+     * @param string         $option
+     * @param string         $expected
+     * @param mixed          $value
+     * @param int            $code
+     * @param Exception|null $previous
+     */
+    public function __construct(
+        string $option,
+        string $expected,
+        $value,
+        int $code = 0,
+        Exception $previous = null
+    ) {
+        parent::__construct(
+            \sprintf(
+                'Option "%s" must be %s, got "%s".',
+                $option,
+                $expected,
+                \is_object($value) ? \get_class($value) : (null === $value ? '<null>' : \gettype($value) . '#' . $value)
+            ),
+            $code,
+            $previous
+        );
+    }
+}

src/Output/StrictUnifiedDiffOutputBuilder.php

+<?php declare(strict_types=1);
+/*
+ * This file is part of sebastian/diff.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace SebastianBergmann\Diff\Output;
+
+use SebastianBergmann\Diff\ConfigurationException;
+
+/**
+ * Strict Unified diff output builder.
+ *
+ * @name Unified diff output builder
+ *
+ * @description Generates (strict) Unified diff's (unidiffs) with hunks.
+ *
+ * @author SpacePossum
+ *
+ * @api
+ */
+final class StrictUnifiedDiffOutputBuilder implements DiffOutputBuilderInterface
+{
+    /**
+     * @var int
+     */
+    private static $noNewlineAtOEFid = 998877;
+
+    /**
+     * @var bool
+     */
+    private $changed;
+
+    /**
+     * @var bool
+     */
+    private $collapseRanges;
+
+    /**
+     * @var int >= 0
+     */
+    private $commonLineThreshold;
+
+    /**
+     * @var string
+     */
+    private $header;
+
+    /**
+     * @var int >= 0
+     */
+    private $contextLines;
+
+    private static $default = [
+        'collapseRanges'      => true, // ranges of length one are rendered with the trailing `,1`
+        'commonLineThreshold' => 6,    // number of same lines before ending a new hunk and creating a new one (if needed)
+        'contextLines'        => 3,    // like `diff:  -u, -U NUM, --unified[=NUM]`, for patch/git apply compatibility best to keep at least @ 3
+        'fromFile'            => null,
+        'fromFileDate'        => null,
+        'toFile'              => null,
+        'toFileDate'          => null,
+    ];
+
+    public function __construct(array $options = [])
+    {
+        $options = \array_merge(self::$default, $options);
+
+        if (!\is_bool($options['collapseRanges'])) {
+            throw new ConfigurationException('collapseRanges', 'a bool', $options['collapseRanges']);
+        }
+
+        if (!\is_int($options['contextLines']) || $options['contextLines'] < 0) {
+            throw new ConfigurationException('contextLines', 'an int >= 0', $options['contextLines']);
+        }
+
+        if (!\is_int($options['commonLineThreshold']) || $options['commonLineThreshold'] < 1) {
+            throw new ConfigurationException('commonLineThreshold', 'an int > 0', $options['commonLineThreshold']);
+        }
+
+        foreach (['fromFile', 'toFile'] as $option) {
+            if (!\is_string($options[$option])) {
+                throw new ConfigurationException($option, 'a string', $options[$option]);
+            }
+        }
+
+        foreach (['fromFileDate', 'toFileDate'] as $option) {
+            if (null !== $options[$option] && !\is_string($options[$option])) {
+                throw new ConfigurationException($option, 'a string or <null>', $options[$option]);
+            }
+        }
+
+        $this->header = \sprintf(
+            "--- %s%s\n+++ %s%s\n",
+            $options['fromFile'],
+            null === $options['fromFileDate'] ? '' : "\t" . $options['fromFileDate'],
+            $options['toFile'],
+            null === $options['toFileDate'] ? '' : "\t" . $options['toFileDate']
+        );
+
+        $this->collapseRanges      = $options['collapseRanges'];
+        $this->commonLineThreshold = $options['commonLineThreshold'];
+        $this->contextLines        = $options['contextLines'];
+    }
+
+    public function getDiff(array $diff): string
+    {
+        if (0 === \count($diff)) {
+            return '';
+        }
+
+        $this->changed = false;
+
+        $buffer = \fopen('php://memory', 'r+b');
+        \fwrite($buffer, $this->header);
+
+        $this->writeDiffHunks($buffer, $diff);
+
+        if (!$this->changed) {
+            \fclose($buffer);
+
+            return '';
+        }
+
+        $diff = \stream_get_contents($buffer, -1, 0);
+
+        \fclose($buffer);
+
+        // If the last char is not a linebreak: add it.
+        // This might happen when both the `from` and `to` do not have a trailing linebreak
+        $last = \substr($diff, -1);
+
+        return "\n" !== $last && "\r" !== $last
+            ? $diff . "\n"
+            : $diff
+        ;
+    }
+
+    private function writeDiffHunks($output, array $diff)
+    {
+        // detect "No newline at end of file" and insert into `$diff` if needed
+
+        $upperLimit = \count($diff);
+
+        if (0 === $diff[$upperLimit - 1][1]) {
+            $lc = \substr($diff[$upperLimit - 1][0], -1);
+            if ("\n" !== $lc) {
+                \array_splice($diff, $upperLimit, 0, [["\n\\ No newline at end of file\n", self::$noNewlineAtOEFid]]);
+            }
+        } else {
+            // search back for the last `+` and `-` line,
+            // check if has trailing linebreak, else add under it warning under it
+            $toFind = [1 => true, 2 => true];
+            for ($i = $upperLimit - 1; $i >= 0; --$i) {
+                if (isset($toFind[$diff[$i][1]])) {
+                    unset($toFind[$diff[$i][1]]);
+                    $lc = \substr($diff[$i][0], -1);
+                    if ("\n" !== $lc) {
+                        \array_splice($diff, $i + 1, 0, [["\n\\ No newline at end of file\n", self::$noNewlineAtOEFid]]);
+                    }
+
+                    if (!\count($toFind)) {
+                        break;
+                    }
+                }
+            }
+        }
+
+        // write hunks to output buffer
+
+        $cutOff      = \max($this->commonLineThreshold, $this->contextLines);
+        $hunkCapture = false;
+        $sameCount   = $toRange = $fromRange = 0;
+        $toStart     = $fromStart = 1;
+
+        foreach ($diff as $i => $entry) {
+            if (0 === $entry[1]) { // same
+                if (false === $hunkCapture) {
+                    ++$fromStart;
+                    ++$toStart;
+
+                    continue;
+                }
+
+                ++$sameCount;
+                ++$toRange;
+                ++$fromRange;
+
+                if ($sameCount === $cutOff) {
+                    $contextStartOffset = ($hunkCapture - $this->contextLines) < 0
+                        ? $hunkCapture
+                        : $this->contextLines
+                    ;
+
+                    // note: $contextEndOffset = $this->contextLines;
+                    //
+                    // because we never go beyond the end of the diff.
+                    // with the cutoff/contextlines here the follow is never true;
+                    //
+                    // if ($i - $cutOff + $this->contextLines + 1 > \count($diff)) {
+                    //    $contextEndOffset = count($diff) - 1;
+                    // }
+                    //
+                    // ; that would be true for a trailing incomplete hunk case which is dealt with after this loop
+
+                    $this->writeHunk(
+                        $diff,
+                        $hunkCapture - $contextStartOffset,
+                        $i - $cutOff + $this->contextLines + 1,
+                        $fromStart - $contextStartOffset,
+                        $fromRange - $cutOff + $contextStartOffset + $this->contextLines,
+                        $toStart - $contextStartOffset,
+                        $toRange - $cutOff + $contextStartOffset + $this->contextLines,
+                        $output
+                    );
+
+                    $fromStart += $fromRange;
+                    $toStart += $toRange;
+
+                    $hunkCapture = false;
+                    $sameCount   = $toRange = $fromRange = 0;
+                }
+
+                continue;
+            }
+
+            $sameCount = 0;
+
+            if ($entry[1] === self::$noNewlineAtOEFid) {
+                continue;
+            }
+
+            $this->changed = true;
+
+            if (false === $hunkCapture) {
+                $hunkCapture = $i;
+            }
+
+            if (1 === $entry[1]) { // added
+                ++$toRange;
+            }
+
+            if (2 === $entry[1]) { // removed
+                ++$fromRange;
+            }
+        }
+
+        if (false === $hunkCapture) {
+            return;
+        }
+
+        // we end here when cutoff (commonLineThreshold) was not reached, but we where capturing a hunk,
+        // do not render hunk till end automatically because the number of context lines might be less than the commonLineThreshold
+
+        $contextStartOffset = $hunkCapture - $this->contextLines < 0
+            ? $hunkCapture
+            : $this->contextLines
+        ;
+
+        // prevent trying to write out more common lines than there are in the diff _and_
+        // do not write more than configured through the context lines
+        $contextEndOffset = \min($sameCount, $this->contextLines);
+
+        $fromRange -= $sameCount;
+        $toRange -= $sameCount;
+
+        $this->writeHunk(
+            $diff,
+            $hunkCapture - $contextStartOffset,
+            $i - $sameCount + $contextEndOffset + 1,
+            $fromStart - $contextStartOffset,
+            $fromRange + $contextStartOffset + $contextEndOffset,
+            $toStart - $contextStartOffset,
+            $toRange + $contextStartOffset + $contextEndOffset,
+            $output
+        );
+    }
+
+    private function writeHunk(
+        array $diff,
+        int $diffStartIndex,
+        int $diffEndIndex,
+        int $fromStart,
+        int $fromRange,
+        int $toStart,
+        int $toRange,
+        $output
+    ) {
+        \fwrite($output, '@@ -' . $fromStart);
+
+        if (!$this->collapseRanges || 1 !== $fromRange) {
+            \fwrite($output, ',' . $fromRange);
+        }
+
+        \fwrite($output, ' +' . $toStart);
+        if (!$this->collapseRanges || 1 !== $toRange) {
+            \fwrite($output, ',' . $toRange);
+        }
+
+        \fwrite($output, " @@\n");
+
+        for ($i = $diffStartIndex; $i < $diffEndIndex; ++$i) {
+            if ($diff[$i][1] === 1) { // added
+                $this->changed = true;
+                \fwrite($output, '+' . $diff[$i][0]);
+            } elseif ($diff[$i][1] === 2) { // removed
+                $this->changed = true;
+                \fwrite($output, '-' . $diff[$i][0]);
+            } elseif ($diff[$i][1] === 0) { // same
+                \fwrite($output, ' ' . $diff[$i][0]);
+            } elseif ($diff[$i][1] === self::$noNewlineAtOEFid) {
+                $this->changed = true;
+                \fwrite($output, $diff[$i][0]);
+            }
+            //} elseif ($diff[$i][1] === 3) { // custom comment inserted by PHPUnit/diff package
+                //  skip
+            //} else {
+                //  unknown/invalid
+            //}
+        }
+    }
+}

src/Output/UnifiedDiffOutputBuilder.php

@@ -15,6 +15,26 @@ namespace SebastianBergmann\Diff\Output;
  */
 final class UnifiedDiffOutputBuilder extends AbstractChunkOutputBuilder
 {
+    /**
+     * @var int
+     */
+    private static $noNewlineAtOEFid = 998877;
+
+    /**
+     * @var bool
+     */
+    private $collapseRanges = true;
+
+    /**
+     * @var int >= 0
+     */
+    private $commonLineThreshold = 6;
+
+    /**
+     * @var int >= 0
+     */
+    private $contextLines = 3;
+
     /**
      * @var string
      */
@@ -42,84 +62,181 @@ final class UnifiedDiffOutputBuilder extends AbstractChunkOutputBuilder
             }
         }
 
-        $this->writeDiffChunked($buffer, $diff, $this->getCommonChunks($diff));
+        if (0 !== \count($diff)) {
+            $this->writeDiffHunks($buffer, $diff);
+        }
 
         $diff = \stream_get_contents($buffer, -1, 0);
 
         \fclose($buffer);
 
-        return $diff;
+        // If the last char is not a linebreak: add it.
+        // This might happen when both the `from` and `to` do not have a trailing linebreak
+        $last = \substr($diff, -1);
+
+        return "\n" !== $last && "\r" !== $last
+            ? $diff . "\n"
+            : $diff
+            ;
     }
 
-    // `old` is an array with key => value pairs . Each pair represents a start and end index of `diff`
-    // of a list of elements all containing `same` (0) entries.
-    private function writeDiffChunked($output, array $diff, array $old)
+    private function writeDiffHunks($output, array $diff)
     {
+        // detect "No newline at end of file" and insert into `$diff` if needed
+
         $upperLimit = \count($diff);
-        $start      = 0;
-        $fromStart  = 0;
-        $toStart    = 0;
 
-        if (\count($old)) { // no common parts, list all diff entries
-            \reset($old);
+        if (0 === $diff[$upperLimit - 1][1]) {
+            $lc = \substr($diff[$upperLimit - 1][0], -1);
+            if ("\n" !== $lc) {
+                \array_splice($diff, $upperLimit, 0, [["\n\\ No newline at end of file\n", self::$noNewlineAtOEFid]]);
+            }
+        } else {
+            // search back for the last `+` and `-` line,
+            // check if has trailing linebreak, else add under it warning under it
+            $toFind = [1 => true, 2 => true];
+            for ($i = $upperLimit - 1; $i >= 0; --$i) {
+                if (isset($toFind[$diff[$i][1]])) {
+                    unset($toFind[$diff[$i][1]]);
+                    $lc = \substr($diff[$i][0], -1);
+                    if ("\n" !== $lc) {
+                        \array_splice($diff, $i + 1, 0, [["\n\\ No newline at end of file\n", self::$noNewlineAtOEFid]]);
+                    }
 
-            // iterate the diff, go from chunk to chunk skipping common chunk of lines between those
-            do {
-                $commonStart = \key($old);
-                $commonEnd   = \current($old);
+                    if (!\count($toFind)) {
+                        break;
+                    }
+                }
+            }
+        }
+
+        // write hunks to output buffer
+
+        $cutOff      = \max($this->commonLineThreshold, $this->contextLines);
+        $hunkCapture = false;
+        $sameCount   = $toRange   = $fromRange = 0;
+        $toStart     = $fromStart = 1;
 
-                if ($commonStart !== $start) {
-                    list($fromRange, $toRange) = $this->getChunkRange($diff, $start, $commonStart);
-                    $this->writeChunk($output, $diff, $start, $commonStart, $fromStart, $fromRange, $toStart, $toRange);
+        foreach ($diff as $i => $entry) {
+            if (0 === $entry[1]) { // same
+                if (false === $hunkCapture) {
+                    ++$fromStart;
+                    ++$toStart;
+
+                    continue;
+                }
+
+                ++$sameCount;
+                ++$toRange;
+                ++$fromRange;
+
+                if ($sameCount === $cutOff) {
+                    $contextStartOffset = ($hunkCapture - $this->contextLines) < 0
+                        ? $hunkCapture
+                        : $this->contextLines
+                    ;
+
+                    // note: $contextEndOffset = $this->contextLines;
+                    //
+                    // because we never go beyond the end of the diff.
+                    // with the cutoff/contextlines here the follow is never true;
+                    //
+                    // if ($i - $cutOff + $this->contextLines + 1 > \count($diff)) {
+                    //    $contextEndOffset = count($diff) - 1;
+                    // }
+                    //
+                    // ; that would be true for a trailing incomplete hunk case which is dealt with after this loop
+
+                    $this->writeHunk(
+                        $diff,
+                        $hunkCapture - $contextStartOffset,
+                        $i - $cutOff + $this->contextLines + 1,
+                        $fromStart - $contextStartOffset,
+                        $fromRange - $cutOff + $contextStartOffset + $this->contextLines,
+                        $toStart - $contextStartOffset,
+                        $toRange - $cutOff + $contextStartOffset + $this->contextLines,
+                        $output
+                    );
 
                     $fromStart += $fromRange;
                     $toStart += $toRange;
+
+                    $hunkCapture = false;
+                    $sameCount   = $toRange = $fromRange = 0;
                 }
 
-                $start        = $commonEnd + 1;
-                $commonLength = $commonEnd - $commonStart + 1; // calculate number of non-change lines in the common part
-                $fromStart += $commonLength;
-                $toStart += $commonLength;
-            } while (false !== \next($old));
-
-            \end($old); // short cut for finding possible last `change entry`
-            $tmp = \key($old);
-            \reset($old);
-            if ($old[$tmp] === $upperLimit - 1) {
-                $upperLimit = $tmp;
+                continue;
+            }
+
+            $sameCount = 0;
+
+            if ($entry[1] === self::$noNewlineAtOEFid) {
+                continue;
+            }
+
+            if (false === $hunkCapture) {
+                $hunkCapture = $i;
             }
-        }
 
-        if ($start < $upperLimit - 1) { // check for trailing (non) diff entries
-            do {
-                --$upperLimit;
-            } while (isset($diff[$upperLimit][1]) && $diff[$upperLimit][1] === 0);
-            ++$upperLimit;
+            if (1 === $entry[1]) { // added
+                ++$toRange;
+            }
+
+            if (2 === $entry[1]) { // removed
+                ++$fromRange;
+            }
+        }
 
-            list($fromRange, $toRange) = $this->getChunkRange($diff, $start, $upperLimit);
-            $this->writeChunk($output, $diff, $start, $upperLimit, $fromStart, $fromRange, $toStart, $toRange);
+        if (false === $hunkCapture) {
+            return;
         }
+
+        // we end here when cutoff (commonLineThreshold) was not reached, but we where capturing a hunk,
+        // do not render hunk till end automatically because the number of context lines might be less than the commonLineThreshold
+
+        $contextStartOffset = $hunkCapture - $this->contextLines < 0
+            ? $hunkCapture
+            : $this->contextLines
+        ;
+
+        // prevent trying to write out more common lines than there are in the diff _and_
+        // do not write more than configured through the context lines
+        $contextEndOffset = \min($sameCount, $this->contextLines);
+
+        $fromRange -= $sameCount;
+        $toRange -= $sameCount;
+
+        $this->writeHunk(
+            $diff,
+            $hunkCapture - $contextStartOffset,
+            $i - $sameCount + $contextEndOffset + 1,
+            $fromStart - $contextStartOffset,
+            $fromRange + $contextStartOffset + $contextEndOffset,
+            $toStart - $contextStartOffset,
+            $toRange + $contextStartOffset + $contextEndOffset,
+            $output
+        );
     }
 
-    private function writeChunk(
-        $output,
+    private function writeHunk(
         array $diff,
         int $diffStartIndex,
         int $diffEndIndex,
         int $fromStart,
         int $fromRange,
         int $toStart,
-        int $toRange
+        int $toRange,
+        $output
     ) {
         if ($this->addLineNumbers) {
-            \fwrite($output, '@@ -' . (1 + $fromStart));
+            \fwrite($output, '@@ -' . $fromStart);
 
-            if ($fromRange !== 1) {
+            if (!$this->collapseRanges || 1 !== $fromRange) {
                 \fwrite($output, ',' . $fromRange);
             }
 
-            \fwrite($output, ' +' . (1 + $toStart));
-            if ($toRange !== 1) {
+            \fwrite($output, ' +' . $toStart);
+            if (!$this->collapseRanges || 1 !== $toRange) {
                 \fwrite($output, ',' . $toRange);
             }
 
@@ -129,37 +246,17 @@ final class UnifiedDiffOutputBuilder extends AbstractChunkOutputBuilder
         }
 
         for ($i = $diffStartIndex; $i < $diffEndIndex; ++$i) {
-            if ($diff[$i][1] === 1 /* ADDED */) {
+            if ($diff[$i][1] === 1) { // added
                 \fwrite($output, '+' . $diff[$i][0]);
-            } elseif ($diff[$i][1] === 2 /* REMOVED */) {
+            } elseif ($diff[$i][1] === 2) { // removed
                 \fwrite($output, '-' . $diff[$i][0]);
+            } elseif ($diff[$i][1] === 0) { // same
+                \fwrite($output, ' ' . $diff[$i][0]);
+            } elseif ($diff[$i][1] === self::$noNewlineAtOEFid) {
+                \fwrite($output, "\n"); // $diff[$i][0]
             } else { /* Not changed (old) 0 or Warning 3 */
                 \fwrite($output, ' ' . $diff[$i][0]);
             }
-
-            $lc = \substr($diff[$i][0], -1);
-            if ($lc !== "\n" && $lc !== "\r") {
-                \fwrite($output, "\n"); // \No newline at end of file
-            }
         }
     }
-
-    private function getChunkRange(array $diff, int $diffStartIndex, int $diffEndIndex): array
-    {
-        $toRange   = 0;
-        $fromRange = 0;
-
-        for ($i = $diffStartIndex; $i < $diffEndIndex; ++$i) {
-            if ($diff[$i][1] === 1) { // added
-                ++$toRange;
-            } elseif ($diff[$i][1] === 2) { // removed
-                ++$fromRange;
-            } elseif ($diff[$i][1] === 0) { // same
-                ++$fromRange;
-                ++$toRange;
-            }
-        }
-
-        return [$fromRange, $toRange];
-    }
 }

tests/DifferTest.php

@@ -99,7 +99,7 @@ final class DifferTest extends TestCase
 -one
 +two
 ',
-            $this->differ->diff(array('one'), array('two'))
+            $this->differ->diff(['one'], ['two'])
         );
     }
 
@@ -273,42 +273,7 @@ final class DifferTest extends TestCase
                 'b',
             ],
             [
-                "--- Original\n+++ New\n@@ @@\n-ba\n+bc\n",
-                'ba',
-                'bc',
-            ],
-            [
-                "--- Original\n+++ New\n@@ @@\n-ab\n+cb\n",
-                'ab',
-                'cb',
-            ],
-            [
-                "--- Original\n+++ New\n@@ @@\n-abc\n+adc\n",
-                'abc',
-                'adc',
-            ],
-            [
-                "--- Original\n+++ New\n@@ @@\n-ab\n+abc\n",
-                'ab',
-                'abc',
-            ],
-            [
-                "--- Original\n+++ New\n@@ @@\n-bc\n+abc\n",
-                'bc',
-                'abc',
-            ],
-            [
-                "--- Original\n+++ New\n@@ @@\n-abc\n+abbc\n",
-                'abc',
-                'abbc',
-            ],
-            [
-                "--- Original\n+++ New\n@@ @@\n-abcdde\n+abcde\n",
-                'abcdde',
-                'abcde',
-            ],
-            [
-                "--- Original\n+++ New\n@@ @@\n-A\n+A1\n",
+                "--- Original\n+++ New\n@@ @@\n-A\n+A1\n B\n",
                 "A\nB",
                 "A1\nB",
             ],
@@ -320,14 +285,21 @@ final class DifferTest extends TestCase
  a
 -b
 +p
+ c
+ d
+ e
 @@ @@
+ g
+ h
+ i
 -j
 +w
+ k
 
 EOF
             ,
-                "a\nb\nc\nd\ne\nf\ng\nh\ni\nj\nk",
-                "a\np\nc\nd\ne\nf\ng\nh\ni\nw\nk",
+                "a\nb\nc\nd\ne\nf\ng\nh\ni\nj\nk\n",
+                "a\np\nc\nd\ne\nf\ng\nh\ni\nw\nk\n",
             ],
             [
                 <<<EOF
@@ -336,19 +308,22 @@ EOF
 @@ @@
 -A
 +B
+ 1
+ 2
+ 3
 
 EOF
             ,
-                "A\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1",
-                "B\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1",
+                "A\n1\n2\n3\n4\n5\n6\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n",
+                "B\n1\n2\n3\n4\n5\n6\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n",
             ],
             [
-                "--- Original\n+++ New\n@@ @@\n #Warning: Strings contain different line endings!\n-<?php\r\n+<?php\n",
+                "--- Original\n+++ New\n@@ @@\n #Warning: Strings contain different line endings!\n-<?php\r\n+<?php\n A\n",
                 "<?php\r\nA\n",
                 "<?php\nA\n",
             ],
             [
-                "--- Original\n+++ New\n@@ @@\n #Warning: Strings contain different line endings!\n-a\r\n+\n+c\r",
+                "--- Original\n+++ New\n@@ @@\n #Warning: Strings contain different line endings!\n-a\r\n+\n+c\r\n",
                 "a\r\n",
                 "\nc\r",
             ],

tests/Exception/ConfigurationExceptionTest.php

+<?php declare(strict_types=1);
+/*
+ * This file is part of sebastian/diff.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace SebastianBergmann\Diff;
+
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @author SpacePossum
+ *
+ * @covers SebastianBergmann\Diff\ConfigurationException
+ *
+ * @internal
+ */
+final class ConfigurationExceptionTest extends TestCase
+{
+    public function testConstruct()
+    {
+        $e = new ConfigurationException('test', 'A', 'B');
+
+        $this->assertSame(0, $e->getCode());
+        $this->assertNull($e->getPrevious());
+        $this->assertSame('Option "test" must be A, got "string#B".', $e->getMessage());
+    }
+}

tests/Output/Integration/StrictUnifiedDiffOutputBuilderIntegrationTest.php

+<?php declare(strict_types=1);
+/*
+ * This file is part of sebastian/diff.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace SebastianBergmann\Diff\Output;
+
+use PHPUnit\Framework\TestCase;
+use SebastianBergmann\Diff\Differ;
+use SebastianBergmann\Diff\Utils\UnifiedDiffAssertTrait;
+use Symfony\Component\Process\Process;
+
+/**
+ * @author SpacePossum
+ *
+ * @requires OS Linux
+ *
+ * @coversNothing
+ *
+ * @internal
+ */
+final class StrictUnifiedDiffOutputBuilderIntegrationTest extends TestCase
+{
+    use UnifiedDiffAssertTrait;
+
+    private $dir;
+
+    private $fileFrom;
+
+    private $fileTo;
+
+    private $filePatch;
+
+    protected function setUp()
+    {
+        $this->dir       = realpath(__DIR__ . '/../../fixtures/out').'/';
+        $this->fileFrom  = $this->dir . 'from.txt';
+        $this->fileTo    = $this->dir . 'to.txt';
+        $this->filePatch = $this->dir . 'diff.patch';
+
+        if (!is_dir($this->dir)) {
+            throw new \RuntimeException('Integration test working directory not found.');
+        }
+
+        $this->cleanUpTempFiles();
+    }
+
+    /**
+     * Integration test
+     *
+     * - get a file pair
+     * - create a `diff` between the files
+     * - test applying the diff using `git apply`
+     * - test applying the diff using `patch`
+     *
+     * @param string $fileFrom
+     * @param string $fileTo
+     *
+     * @dataProvider provideFilePairs
+     */
+    public function testIntegrationUsingPHPFileInVendorGitApply(string $fileFrom, string $fileTo)
+    {
+        $from = self::getFileContent($fileFrom);
+        $to   = self::getFileContent($fileTo);
+
+        $diff = (new Differ(new StrictUnifiedDiffOutputBuilder(['fromFile' => 'Original', 'toFile' => 'New'])))->diff($from, $to);
+
+        if ('' === $diff && $from === $to) {
+            // odd case: test after executing as it is more efficient than to read the files and check the contents every time
+            $this->addToAssertionCount(1);
+
+            return;
+        }
+
+        $this->doIntegrationTestGitApply($diff, $from, $to);
+    }
+
+    /**
+     * Integration test
+     *
+     * - get a file pair
+     * - create a `diff` between the files
+     * - test applying the diff using `git apply`
+     * - test applying the diff using `patch`
+     *
+     * @param string $fileFrom
+     * @param string $fileTo
+     *
+     * @dataProvider provideFilePairs
+     */
+    public function testIntegrationUsingPHPFileInVendorPatch(string $fileFrom, string $fileTo)
+    {
+        $from = self::getFileContent($fileFrom);
+        $to   = self::getFileContent($fileTo);
+
+        $diff = (new Differ(new StrictUnifiedDiffOutputBuilder(['fromFile' => 'Original', 'toFile' => 'New'])))->diff($from, $to);
+
+        if ('' === $diff && $from === $to) {
+            // odd case: test after executing as it is more efficient than to read the files and check the contents every time
+            $this->addToAssertionCount(1);
+
+            return;
+        }
+
+        $this->doIntegrationTestPatch($diff, $from, $to);
+    }
+
+    /**
+     * @param string $expected
+     * @param string $from
+     * @param string $to
+     *
+     * @dataProvider provideOutputBuildingCases
+     * @dataProvider provideSample
+     * @dataProvider provideBasicDiffGeneration
+     */
+    public function testIntegrationOfUnitTestCasesGitApply(string $expected, string $from, string $to)
+    {
+        $this->doIntegrationTestGitApply($expected, $from, $to);
+    }
+
+    /**
+     * @param string $expected
+     * @param string $from
+     * @param string $to
+     *
+     * @dataProvider provideOutputBuildingCases
+     * @dataProvider provideSample
+     * @dataProvider provideBasicDiffGeneration
+     */
+    public function testIntegrationOfUnitTestCasesPatch(string $expected, string $from, string $to)
+    {
+        $this->doIntegrationTestPatch($expected, $from, $to);
+    }
+
+    public function provideOutputBuildingCases(): array
+    {
+        return StrictUnifiedDiffOutputBuilderDataProvider::provideOutputBuildingCases();
+    }
+
+    public function provideSample(): array
+    {
+        return StrictUnifiedDiffOutputBuilderDataProvider::provideSample();
+    }
+
+    public function provideBasicDiffGeneration(): array
+    {
+        return StrictUnifiedDiffOutputBuilderDataProvider::provideBasicDiffGeneration();
+    }
+
+    public function provideFilePairs(): array
+    {
+        $cases     = [];
+        $fromFile  = __FILE__;
+        $vendorDir = \realpath(__DIR__ . '/../../../vendor');
+
+        $fileIterator = new \RecursiveIteratorIterator(new \RecursiveDirectoryIterator($vendorDir, \RecursiveDirectoryIterator::SKIP_DOTS));
+
+        /** @var \SplFileInfo $file */
+        foreach ($fileIterator as $file) {
+            if ('php' !== $file->getExtension()) {
+                continue;
+            }
+
+            $toFile                                                                                         = $file->getPathname();
+            $cases[\sprintf("Diff file:\n\"%s\"\nvs.\n\"%s\"\n", \realpath($fromFile), \realpath($toFile))] = [$fromFile, $toFile];
+            $fromFile                                                                                       = $toFile;
+        }
+
+        return $cases;
+    }
+
+    /**
+     * Compare diff create by builder and against one create by `diff` command.
+     *
+     * @param string $diff
+     * @param string $from
+     * @param string $to
+     *
+     * @dataProvider provideBasicDiffGeneration
+     */
+    public function testIntegrationDiffOutputBuilderVersusDiffCommand(string $diff, string $from, string $to)
+    {
+        $this->assertNotSame('', $diff);
+        $this->assertValidUnifiedDiffFormat($diff);
+
+        $this->assertNotFalse(\file_put_contents($this->fileFrom, $from));
+        $this->assertNotFalse(\file_put_contents($this->fileTo, $to));
+
+        $p = new Process(\sprintf('diff -u %s %s', \escapeshellarg($this->fileFrom), \escapeshellarg($this->fileTo)));
+        $p->run();
+        $this->assertSame(1, $p->getExitCode()); // note: Process assumes exit code 0 for `isSuccessful`, however `diff` uses the exit code `1` for success with diff
+
+        $output = $p->getOutput();
+
+        $diffLines    = \preg_split('/(.*\R)/', $diff, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
+        $diffLines[0] = \preg_replace('#^\-\-\- .*#', '--- /' . $this->fileFrom, $diffLines[0], 1);
+        $diffLines[1] = \preg_replace('#^\+\+\+ .*#', '+++ /' . $this->fileFrom, $diffLines[1], 1);
+        $diff         = \implode('', $diffLines);
+
+        $outputLines    = \preg_split('/(.*\R)/', $output, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
+        $outputLines[0] = \preg_replace('#^\-\-\- .*#', '--- /' . $this->fileFrom, $outputLines[0], 1);
+        $outputLines[1] = \preg_replace('#^\+\+\+ .*#', '+++ /' . $this->fileFrom, $outputLines[1], 1);
+        $output         = \implode('', $outputLines);
+
+        $this->assertSame($diff, $output);
+    }
+
+    private function doIntegrationTestGitApply(string $diff, string $from, string $to)
+    {
+        $this->assertNotSame('', $diff);
+        $this->assertValidUnifiedDiffFormat($diff);
+
+        $diff = self::setDiffFileHeader($diff, $this->fileFrom);
+
+        $this->assertNotFalse(\file_put_contents($this->fileFrom, $from));
+        $this->assertNotFalse(\file_put_contents($this->filePatch, $diff));
+
+        $p = new Process(\sprintf(
+            'git --git-dir %s apply --check -v --unsafe-paths --ignore-whitespace %s',
+            \escapeshellarg($this->dir),
+            \escapeshellarg($this->filePatch)
+        ));
+
+        $p->run();
+
+        $this->assertProcessSuccessful($p);
+    }
+
+    private function doIntegrationTestPatch(string $diff, string $from, string $to)
+    {
+        $this->assertNotSame('', $diff);
+        $this->assertValidUnifiedDiffFormat($diff);
+
+        $diff = self::setDiffFileHeader($diff, $this->fileFrom);
+
+        $this->assertNotFalse(\file_put_contents($this->fileFrom, $from));
+        $this->assertNotFalse(\file_put_contents($this->filePatch, $diff));
+
+        $command = \sprintf(
+            'patch -u --verbose --posix %s < %s',
+            \escapeshellarg($this->fileFrom),
+            \escapeshellarg($this->filePatch)
+        );
+
+        $p = new Process($command);
+        $p->run();
+
+        $this->assertProcessSuccessful($p);
+
+        $this->assertStringEqualsFile(
+            $this->fileFrom,
+            $to,
+            \sprintf('Patch command "%s".', $command)
+        );
+    }
+
+    protected function tearDown()
+    {
+        $this->cleanUpTempFiles();
+    }
+
+    private function assertProcessSuccessful(Process $p)
+    {
+        $this->assertTrue(
+            $p->isSuccessful(),
+            \sprintf(
+                "Command exec. was not successful:\n\"%s\"\nOutput:\n\"%s\"\nStdErr:\n\"%s\"\nExit code %d.\n",
+                $p->getCommandLine(),
+                $p->getOutput(),
+                $p->getErrorOutput(),
+                $p->getExitCode()
+            )
+        );
+    }
+
+    private function cleanUpTempFiles()
+    {
+        @\unlink($this->fileFrom . '.orig');
+        @\unlink($this->fileFrom . '.rej');
+        @\unlink($this->fileFrom);
+        @\unlink($this->fileTo);
+        @\unlink($this->filePatch);
+    }
+
+    private static function setDiffFileHeader(string $diff, string $file): string
+    {
+        $diffLines    = \preg_split('/(.*\R)/', $diff, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
+        $diffLines[0] = \preg_replace('#^\-\-\- .*#', '--- /' . $file, $diffLines[0], 1);
+        $diffLines[1] = \preg_replace('#^\+\+\+ .*#', '+++ /' . $file, $diffLines[1], 1);
+
+        return \implode('', $diffLines);
+    }
+
+    private static function getFileContent(string $file): string
+    {
+        $content = @\file_get_contents($file);
+        if (false === $content) {
+            $error = \error_get_last();
+
+            throw new \RuntimeException(\sprintf(
+                'Failed to read content of file "%s".%s',
+                $file,
+                $error ? ' ' . $error['message'] : ''
+            ));
+        }
+
+        return $content;
+    }
+}

tests/Output/UnifiedDiffOutputBuilderTestTest.php → tests/Output/Integration/UnifiedDiffOutputBuilderIntegrationTest.php

@@ -11,6 +11,8 @@
 namespace SebastianBergmann\Diff\Output;
 
 use PHPUnit\Framework\TestCase;
+use SebastianBergmann\Diff\Utils\UnifiedDiffAssertTrait;
+use Symfony\Component\Process\Process;
 
 /**
  * @covers SebastianBergmann\Diff\Output\UnifiedDiffOutputBuilder
@@ -21,68 +23,134 @@ use PHPUnit\Framework\TestCase;
  *
  * @requires OS Linux
  */
-final class UnifiedDiffOutputBuilderTestTest extends TestCase
+final class UnifiedDiffOutputBuilderIntegrationTest extends TestCase
 {
+    use UnifiedDiffAssertTrait;
+
+    private $dir;
+
     private $fileFrom;
+
     private $filePatch;
 
     protected function setUp()
     {
-        $dir             = \realpath(__DIR__ . '/../../') . '/';
-        $this->fileFrom  = $dir . 'from.txt';
-        $this->filePatch = $dir . 'patch.txt';
+        $this->dir       = \realpath(__DIR__ . '/../../fixtures/out/') . '/';
+        $this->fileFrom  = $this->dir . 'from.txt';
+        $this->filePatch = $this->dir . 'patch.txt';
+
+        $this->cleanUpTempFiles();
+    }
+
+    /**
+     * @dataProvider provideDiffWithLineNumbers
+     */
+    public function testDiffWithLineNumbersPath($expected, $from, $to)
+    {
+        $this->doIntegrationTestPatch($expected, $from, $to);
     }
 
     /**
      * @dataProvider provideDiffWithLineNumbers
      */
-    public function testTheTestProvideDiffWithLineNumbers($expected, $from, $to)
+    public function testDiffWithLineNumbersGitApply($expected, $from, $to)
     {
-        $this->runThisTest($expected, $from, $to);
+        $this->doIntegrationTestGitApply($expected, $from, $to);
     }
 
     public function provideDiffWithLineNumbers()
     {
-        require_once __DIR__ . '/UnifiedDiffOutputBuilderTest.php';
-        $test  = new UnifiedDiffOutputBuilderTest();
-        $tests = $test->provideDiffWithLineNumbers();
-        $tests = \array_filter(
-            $tests,
-            function ($key) {
+        return \array_filter(
+            UnifiedDiffOutputBuilderDataProvider::provideDiffWithLineNumbers(),
+            static function ($key) {
                 return !\is_string($key) || false === \strpos($key, 'non_patch_compat');
             },
             ARRAY_FILTER_USE_KEY
         );
+    }
 
-        return $tests;
+    protected function tearDown()
+    {
+        $this->cleanUpTempFiles();
     }
 
-    private function runThisTest(string $expected, string $from, string $to)
+    private function doIntegrationTestPatch(string $diff, string $from, string $to)
     {
-        $expected = \str_replace('--- Original', '--- from.txt', $expected);
-        $expected = \str_replace('+++ New', '+++ from.txt', $expected);
+        $this->assertNotSame('', $diff);
+        $this->assertValidUnifiedDiffFormat($diff);
 
-        @\unlink($this->fileFrom);
-        @\unlink($this->filePatch);
+        $diff = self::setDiffFileHeader($diff, $this->fileFrom);
 
         $this->assertNotFalse(\file_put_contents($this->fileFrom, $from));
-        $this->assertNotFalse(\file_put_contents($this->filePatch, $expected));
+        $this->assertNotFalse(\file_put_contents($this->filePatch, $diff));
 
         $command = \sprintf(
-            'patch -u --verbose %s < %s', // --posix
+            'patch -u --verbose --posix  %s < %s', // --posix
             \escapeshellarg($this->fileFrom),
             \escapeshellarg($this->filePatch)
         );
 
-        \exec($command, $output, $d);
+        $p = new Process($command);
+        $p->run();
+
+        $this->assertProcessSuccessful($p);
 
-        $this->assertSame(0, $d, \sprintf('%s | %s', $command, \implode("\n", $output)));
+        $this->assertStringEqualsFile(
+            $this->fileFrom,
+            $to,
+            \sprintf('Patch command "%s".', $command)
+        );
+    }
+
+    private function doIntegrationTestGitApply(string $diff, string $from, string $to)
+    {
+        $this->assertNotSame('', $diff);
+        $this->assertValidUnifiedDiffFormat($diff);
 
-        $patched = \file_get_contents($this->fileFrom);
-        $this->assertSame($patched, $to);
+        $diff = self::setDiffFileHeader($diff, $this->fileFrom);
 
+        $this->assertNotFalse(\file_put_contents($this->fileFrom, $from));
+        $this->assertNotFalse(\file_put_contents($this->filePatch, $diff));
+
+        $command = \sprintf(
+            'git --git-dir %s apply --check -v --unsafe-paths --ignore-whitespace %s',
+            \escapeshellarg($this->dir),
+            \escapeshellarg($this->filePatch)
+        );
+
+        $p = new Process($command);
+        $p->run();
+
+        $this->assertProcessSuccessful($p);
+    }
+
+    private function assertProcessSuccessful(Process $p)
+    {
+        $this->assertTrue(
+            $p->isSuccessful(),
+            \sprintf(
+                "Command exec. was not successful:\n\"%s\"\nOutput:\n\"%s\"\nStdErr:\n\"%s\"\nExit code %d.\n",
+                $p->getCommandLine(),
+                $p->getOutput(),
+                $p->getErrorOutput(),
+                $p->getExitCode()
+            )
+        );
+    }
+
+    private function cleanUpTempFiles()
+    {
         @\unlink($this->fileFrom . '.orig');
         @\unlink($this->fileFrom);
         @\unlink($this->filePatch);
     }
+
+    private static function setDiffFileHeader(string $diff, string $file): string
+    {
+        $diffLines    = \preg_split('/(.*\R)/', $diff, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
+        $diffLines[0] = \preg_replace('#^\-\-\- .*#', '--- /' . $file, $diffLines[0], 1);
+        $diffLines[1] = \preg_replace('#^\+\+\+ .*#', '+++ /' . $file, $diffLines[1], 1);
+
+        return \implode('', $diffLines);
+    }
 }

tests/Output/StrictUnifiedDiffOutputBuilderDataProvider.php

+<?php declare(strict_types=1);
+/*
+ * This file is part of sebastian/diff.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace SebastianBergmann\Diff\Output;
+
+/**
+ * @author SpacePossum
+ *
+ * @coversNothing
+ *
+ * @internal
+ */
+final class StrictUnifiedDiffOutputBuilderDataProvider
+{
+    public static function provideOutputBuildingCases(): array
+    {
+        return [
+            [
+'--- input.txt
++++ output.txt
+@@ -1,3 +1,4 @@
++b
+ ' . '
+ ' . '
+ ' . '
+@@ -16,5 +17,4 @@
+ ' . '
+ ' . '
+ ' . '
+-
+-B
++A
+',
+                "\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\nB\n",
+                "b\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\nA\n",
+                [
+                    'fromFile' => 'input.txt',
+                    'toFile'   => 'output.txt',
+                ],
+            ],
+            [
+'--- ' . __FILE__ . "\t2017-10-02 17:38:11.586413675 +0100
++++ output1.txt\t2017-10-03 12:09:43.086719482 +0100
+@@ -1,1 +1,1 @@
+-B
++X
+",
+                "B\n",
+                "X\n",
+                [
+                    'fromFile'       => __FILE__,
+                    'fromFileDate'   => '2017-10-02 17:38:11.586413675 +0100',
+                    'toFile'         => 'output1.txt',
+                    'toFileDate'     => '2017-10-03 12:09:43.086719482 +0100',
+                    'collapseRanges' => false,
+                ],
+            ],
+            [
+'--- input.txt
++++ output.txt
+@@ -1 +1 @@
+-B
++X
+',
+                "B\n",
+                "X\n",
+                [
+                    'fromFile'       => 'input.txt',
+                    'toFile'         => 'output.txt',
+                    'collapseRanges' => true,
+                ],
+            ],
+        ];
+    }
+
+    public static function provideSample(): array
+    {
+        return [
+            [
+'--- input.txt
++++ output.txt
+@@ -1,6 +1,6 @@
+ 1
+ 2
+ 3
+-4
++X
+ 5
+ 6
+',
+                "1\n2\n3\n4\n5\n6\n",
+                "1\n2\n3\nX\n5\n6\n",
+                [
+                    'fromFile' => 'input.txt',
+                    'toFile'   => 'output.txt',
+                ],
+            ],
+        ];
+    }
+
+    public static function provideBasicDiffGeneration(): array
+    {
+        return [
+            [
+"--- input.txt
++++ output.txt
+@@ -1,2 +1 @@
+-A
+-B
++A\rB
+",
+                "A\nB\n",
+                "A\rB\n",
+            ],
+            [
+"--- input.txt
++++ output.txt
+@@ -1 +1 @@
+-
++\r
+\\ No newline at end of file
+",
+                "\n",
+                "\r",
+            ],
+            [
+"--- input.txt
++++ output.txt
+@@ -1 +1 @@
+-\r
+\\ No newline at end of file
++
+",
+                "\r",
+                "\n",
+            ],
+            [
+'--- input.txt
++++ output.txt
+@@ -1,3 +1,3 @@
+ X
+ A
+-A
++B
+',
+                "X\nA\nA\n",
+                "X\nA\nB\n",
+            ],
+            [
+'--- input.txt
++++ output.txt
+@@ -1,3 +1,3 @@
+ X
+ A
+-A
+\ No newline at end of file
++B
+',
+                "X\nA\nA",
+                "X\nA\nB\n",
+            ],
+            [
+'--- input.txt
++++ output.txt
+@@ -1,3 +1,3 @@
+ A
+ A
+-A
++B
+\ No newline at end of file
+',
+                "A\nA\nA\n",
+                "A\nA\nB",
+            ],
+            [
+'--- input.txt
++++ output.txt
+@@ -1 +1 @@
+-A
+\ No newline at end of file
++B
+\ No newline at end of file
+',
+                'A',
+                'B',
+            ],
+        ];
+    }
+}

tests/Output/StrictUnifiedDiffOutputBuilderTest.php

+<?php declare(strict_types=1);
+/*
+ * This file is part of sebastian/diff.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace SebastianBergmann\Diff\Output;
+
+use PHPUnit\Framework\TestCase;
+use SebastianBergmann\Diff\ConfigurationException;
+use SebastianBergmann\Diff\Differ;
+use SebastianBergmann\Diff\Utils\UnifiedDiffAssertTrait;
+
+/**
+ * @author SpacePossum
+ *
+ * @covers SebastianBergmann\Diff\Output\StrictUnifiedDiffOutputBuilder
+ *
+ * @internal
+ */
+final class StrictUnifiedDiffOutputBuilderTest extends TestCase
+{
+    use UnifiedDiffAssertTrait;
+
+    /**
+     * @param string $expected
+     * @param string $from
+     * @param string $to
+     * @param array  $options
+     *
+     * @dataProvider provideOutputBuildingCases
+     */
+    public function testOutputBuilding(string $expected, string $from, string $to, array $options)
+    {
+        $diff = $this->getDiffer($options)->diff($from, $to);
+
+        $this->assertValidDiffFormat($diff);
+        $this->assertSame($expected, $diff);
+    }
+
+    /**
+     * @param string $expected
+     * @param string $from
+     * @param string $to
+     * @param array  $options
+     *
+     * @dataProvider provideSample
+     */
+    public function testSample(string $expected, string $from, string $to, array $options)
+    {
+        $diff = $this->getDiffer($options)->diff($from, $to);
+
+        $this->assertValidDiffFormat($diff);
+        $this->assertSame($expected, $diff);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function assertValidDiffFormat(string $diff)
+    {
+        $this->assertValidUnifiedDiffFormat($diff);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function provideOutputBuildingCases(): array
+    {
+        return StrictUnifiedDiffOutputBuilderDataProvider::provideOutputBuildingCases();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function provideSample(): array
+    {
+        return StrictUnifiedDiffOutputBuilderDataProvider::provideSample();
+    }
+
+    /**
+     * @param string $expected
+     * @param string $from
+     * @param string $to
+     *
+     * @dataProvider provideBasicDiffGeneration
+     */
+    public function testBasicDiffGeneration(string $expected, string $from, string $to)
+    {
+        $diff = $this->getDiffer([
+            'fromFile' => 'input.txt',
+            'toFile'   => 'output.txt',
+        ])->diff($from, $to);
+
+        $this->assertValidDiffFormat($diff);
+        $this->assertSame($expected, $diff);
+    }
+
+    public function provideBasicDiffGeneration(): array
+    {
+        return StrictUnifiedDiffOutputBuilderDataProvider::provideBasicDiffGeneration();
+    }
+
+    /**
+     * @param string $expected
+     * @param string $from
+     * @param string $to
+     * @param array  $config
+     *
+     * @dataProvider provideConfiguredDiffGeneration
+     */
+    public function testConfiguredDiffGeneration(string $expected, string $from, string $to, array $config = [])
+    {
+        $diff = $this->getDiffer(\array_merge([
+            'fromFile' => 'input.txt',
+            'toFile'   => 'output.txt',
+        ], $config))->diff($from, $to);
+
+        $this->assertValidDiffFormat($diff);
+        $this->assertSame($expected, $diff);
+    }
+
+    public function provideConfiguredDiffGeneration(): array
+    {
+        return [
+            [
+                '--- input.txt
++++ output.txt
+@@ -1 +1 @@
+-a
+\ No newline at end of file
++b
+\ No newline at end of file
+',
+                'a',
+                'b',
+            ],
+            [
+                '',
+                "1\n2",
+                "1\n2",
+            ],
+            [
+                '',
+                "1\n",
+                "1\n",
+            ],
+            [
+'--- input.txt
++++ output.txt
+@@ -4 +4 @@
+-X
++4
+',
+                "1\n2\n3\nX\n5\n6\n7\n8\n9\n0\n",
+                "1\n2\n3\n4\n5\n6\n7\n8\n9\n0\n",
+                [
+                    'contextLines' => 0,
+                ],
+            ],
+            [
+'--- input.txt
++++ output.txt
+@@ -3,3 +3,3 @@
+ 3
+-X
++4
+ 5
+',
+                "1\n2\n3\nX\n5\n6\n7\n8\n9\n0\n",
+                "1\n2\n3\n4\n5\n6\n7\n8\n9\n0\n",
+                [
+                    'contextLines' => 1,
+                ],
+            ],
+            [
+'--- input.txt
++++ output.txt
+@@ -1,10 +1,10 @@
+ 1
+ 2
+ 3
+-X
++4
+ 5
+ 6
+ 7
+ 8
+ 9
+ 0
+',
+                "1\n2\n3\nX\n5\n6\n7\n8\n9\n0\n",
+                "1\n2\n3\n4\n5\n6\n7\n8\n9\n0\n",
+                [
+                    'contextLines' => 999,
+                ],
+            ],
+            [
+'--- input.txt
++++ output.txt
+@@ -1,0 +1,2 @@
++
++A
+',
+                '',
+                "\nA\n",
+            ],
+            [
+'--- input.txt
++++ output.txt
+@@ -1,2 +1,0 @@
+-
+-A
+',
+                "\nA\n",
+                '',
+            ],
+            [
+                '--- input.txt
++++ output.txt
+@@ -1,5 +1,5 @@
+ 1
+-X
++2
+ 3
+-Y
++4
+ 5
+@@ -8,3 +8,3 @@
+ 8
+-X
++9
+ 0
+',
+                "1\nX\n3\nY\n5\n6\n7\n8\nX\n0\n",
+                "1\n2\n3\n4\n5\n6\n7\n8\n9\n0\n",
+                [
+                    'commonLineThreshold' => 2,
+                    'contextLines'        => 1,
+                ],
+            ],
+            [
+                '--- input.txt
++++ output.txt
+@@ -2 +2 @@
+-X
++2
+@@ -4 +4 @@
+-Y
++4
+@@ -9 +9 @@
+-X
++9
+',
+                "1\nX\n3\nY\n5\n6\n7\n8\nX\n0\n",
+                "1\n2\n3\n4\n5\n6\n7\n8\n9\n0\n",
+                [
+                    'commonLineThreshold' => 1,
+                    'contextLines'        => 0,
+                ],
+            ],
+        ];
+    }
+
+    public function testReUseBuilder()
+    {
+        $differ = $this->getDiffer([
+            'fromFile' => 'input.txt',
+            'toFile'   => 'output.txt',
+        ]);
+
+        $diff = $differ->diff("A\nB\n", "A\nX\n");
+        $this->assertSame(
+'--- input.txt
++++ output.txt
+@@ -1,2 +1,2 @@
+ A
+-B
++X
+',
+            $diff
+        );
+
+        $diff = $differ->diff("A\n", "A\n");
+        $this->assertSame(
+            '',
+            $diff
+        );
+    }
+
+    public function testEmptyDiff()
+    {
+        $builder = new StrictUnifiedDiffOutputBuilder([
+            'fromFile' => 'input.txt',
+            'toFile'   => 'output.txt',
+        ]);
+
+        $this->assertSame(
+            '',
+            $builder->getDiff([])
+        );
+    }
+
+    /**
+     * @param array  $options
+     * @param string $message
+     *
+     * @dataProvider provideInvalidConfiguration
+     */
+    public function testInvalidConfiguration(array $options, string $message)
+    {
+        $this->expectException(ConfigurationException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote($message, '#')));
+
+        new StrictUnifiedDiffOutputBuilder($options);
+    }
+
+    public function provideInvalidConfiguration(): array
+    {
+        $time = \time();
+
+        return [
+            [
+                ['collapseRanges' => 1],
+                'Option "collapseRanges" must be a bool, got "integer#1".',
+            ],
+            [
+                ['contextLines' => 'a'],
+                'Option "contextLines" must be an int >= 0, got "string#a".',
+            ],
+            [
+                ['commonLineThreshold' => -2],
+                'Option "commonLineThreshold" must be an int > 0, got "integer#-2".',
+            ],
+            [
+                ['commonLineThreshold' => 0],
+                'Option "commonLineThreshold" must be an int > 0, got "integer#0".',
+            ],
+            [
+                ['fromFile' => new \SplFileInfo(__FILE__)],
+                'Option "fromFile" must be a string, got "SplFileInfo".',
+            ],
+            [
+                ['fromFile' => null],
+                'Option "fromFile" must be a string, got "<null>".',
+            ],
+            [
+                [
+                    'fromFile' => __FILE__,
+                    'toFile'   => 1,
+                ],
+                'Option "toFile" must be a string, got "integer#1".',
+            ],
+            [
+                [
+                    'fromFile'   => __FILE__,
+                    'toFile'     => __FILE__,
+                    'toFileDate' => $time,
+                ],
+                'Option "toFileDate" must be a string or <null>, got "integer#' . $time . '".',
+            ],
+            [
+                [],
+                'Option "fromFile" must be a string, got "<null>".',
+            ],
+        ];
+    }
+
+    /**
+     * @param string $expected
+     * @param string $from
+     * @param string $to
+     * @param int    $threshold
+     *
+     * @dataProvider provideCommonLineThresholdCases
+     */
+    public function testCommonLineThreshold(string $expected, string $from, string $to, int $threshold)
+    {
+        $diff = $this->getDiffer([
+            'fromFile'            => 'input.txt',
+            'toFile'              => 'output.txt',
+            'commonLineThreshold' => $threshold,
+            'contextLines'        => 0,
+        ])->diff($from, $to);
+
+        $this->assertValidDiffFormat($diff);
+        $this->assertSame($expected, $diff);
+    }
+
+    public function provideCommonLineThresholdCases(): array
+    {
+        return [
+            [
+'--- input.txt
++++ output.txt
+@@ -2,3 +2,3 @@
+-X
++B
+ C12
+-Y
++D
+@@ -7 +7 @@
+-X
++Z
+',
+                "A\nX\nC12\nY\nA\nA\nX\n",
+                "A\nB\nC12\nD\nA\nA\nZ\n",
+                2,
+            ],
+            [
+'--- input.txt
++++ output.txt
+@@ -2 +2 @@
+-X
++B
+@@ -4 +4 @@
+-Y
++D
+',
+                "A\nX\nV\nY\n",
+                "A\nB\nV\nD\n",
+                1,
+            ],
+        ];
+    }
+
+    /**
+     * @param string $expected
+     * @param string $from
+     * @param string $to
+     * @param int    $contextLines
+     * @param int    $commonLineThreshold
+     *
+     * @dataProvider provideContextLineConfigurationCases
+     */
+    public function testContextLineConfiguration(string $expected, string $from, string $to, int $contextLines, int $commonLineThreshold = 6)
+    {
+        $diff = $this->getDiffer([
+            'fromFile'            => 'input.txt',
+            'toFile'              => 'output.txt',
+            'contextLines'        => $contextLines,
+            'commonLineThreshold' => $commonLineThreshold,
+        ])->diff($from, $to);
+
+        $this->assertValidDiffFormat($diff);
+        $this->assertSame($expected, $diff);
+    }
+
+    public function provideContextLineConfigurationCases(): array
+    {
+        $from = "A\nB\nC\nD\nE\nF\nX\nG\nH\nI\nJ\nK\nL\nM\n";
+        $to   = "A\nB\nC\nD\nE\nF\nY\nG\nH\nI\nJ\nK\nL\nM\n";
+
+        return [
+            'EOF 0' => [
+                "--- input.txt\n+++ output.txt\n@@ -3 +3 @@
+-X
+\\ No newline at end of file
++Y
+\\ No newline at end of file
+",
+                "A\nB\nX",
+                "A\nB\nY",
+                0,
+            ],
+            'EOF 1' => [
+                "--- input.txt\n+++ output.txt\n@@ -2,2 +2,2 @@
+ B
+-X
+\\ No newline at end of file
++Y
+\\ No newline at end of file
+",
+                "A\nB\nX",
+                "A\nB\nY",
+                1,
+],
+            'EOF 2' => [
+                "--- input.txt\n+++ output.txt\n@@ -1,3 +1,3 @@
+ A
+ B
+-X
+\\ No newline at end of file
++Y
+\\ No newline at end of file
+",
+                "A\nB\nX",
+                "A\nB\nY",
+                2,
+            ],
+            'EOF 200' => [
+                "--- input.txt\n+++ output.txt\n@@ -1,3 +1,3 @@
+ A
+ B
+-X
+\\ No newline at end of file
++Y
+\\ No newline at end of file
+",
+                "A\nB\nX",
+                "A\nB\nY",
+                200,
+            ],
+            'n/a 0' => [
+                "--- input.txt\n+++ output.txt\n@@ -7 +7 @@\n-X\n+Y\n",
+                $from,
+                $to,
+                0,
+            ],
+            'G' => [
+                "--- input.txt\n+++ output.txt\n@@ -6,3 +6,3 @@\n F\n-X\n+Y\n G\n",
+                $from,
+                $to,
+                1,
+            ],
+            'H' => [
+                "--- input.txt\n+++ output.txt\n@@ -5,5 +5,5 @@\n E\n F\n-X\n+Y\n G\n H\n",
+                $from,
+                $to,
+                2,
+            ],
+            'I' => [
+                "--- input.txt\n+++ output.txt\n@@ -4,7 +4,7 @@\n D\n E\n F\n-X\n+Y\n G\n H\n I\n",
+                $from,
+                $to,
+                3,
+            ],
+            'J' => [
+                "--- input.txt\n+++ output.txt\n@@ -3,9 +3,9 @@\n C\n D\n E\n F\n-X\n+Y\n G\n H\n I\n J\n",
+                $from,
+                $to,
+                4,
+            ],
+            'K' => [
+                "--- input.txt\n+++ output.txt\n@@ -2,11 +2,11 @@\n B\n C\n D\n E\n F\n-X\n+Y\n G\n H\n I\n J\n K\n",
+                $from,
+                $to,
+                5,
+            ],
+            'L' => [
+                "--- input.txt\n+++ output.txt\n@@ -1,13 +1,13 @@\n A\n B\n C\n D\n E\n F\n-X\n+Y\n G\n H\n I\n J\n K\n L\n",
+                $from,
+                $to,
+                6,
+            ],
+            'M' => [
+                "--- input.txt\n+++ output.txt\n@@ -1,14 +1,14 @@\n A\n B\n C\n D\n E\n F\n-X\n+Y\n G\n H\n I\n J\n K\n L\n M\n",
+                $from,
+                $to,
+                7,
+            ],
+            'M no linebreak EOF .1' => [
+                "--- input.txt\n+++ output.txt\n@@ -1,14 +1,14 @@\n A\n B\n C\n D\n E\n F\n-X\n+Y\n G\n H\n I\n J\n K\n L\n-M\n+M\n\\ No newline at end of file\n",
+                $from,
+                \substr($to, 0, -1),
+                7,
+            ],
+            'M no linebreak EOF .2' => [
+                "--- input.txt\n+++ output.txt\n@@ -1,14 +1,14 @@\n A\n B\n C\n D\n E\n F\n-X\n+Y\n G\n H\n I\n J\n K\n L\n-M\n\\ No newline at end of file\n+M\n",
+                \substr($from, 0, -1),
+                $to,
+                7,
+            ],
+            'M no linebreak EOF .3' => [
+                "--- input.txt\n+++ output.txt\n@@ -1,14 +1,14 @@\n A\n B\n C\n D\n E\n F\n-X\n+Y\n G\n H\n I\n J\n K\n L\n M\n",
+                \substr($from, 0, -1),
+                \substr($to, 0, -1),
+                7,
+            ],
+            'M no linebreak EOF .4' => [
+                "--- input.txt\n+++ output.txt\n@@ -1,14 +1,14 @@\n A\n B\n C\n D\n E\n F\n-X\n+Y\n G\n H\n I\n J\n K\n L\n M\n\\ No newline at end of file\n",
+                \substr($from, 0, -1),
+                \substr($to, 0, -1),
+                10000,
+                10000,
+            ],
+            'M+1' => [
+                "--- input.txt\n+++ output.txt\n@@ -1,14 +1,14 @@\n A\n B\n C\n D\n E\n F\n-X\n+Y\n G\n H\n I\n J\n K\n L\n M\n",
+                $from,
+                $to,
+                8,
+            ],
+            'M+100' => [
+                "--- input.txt\n+++ output.txt\n@@ -1,14 +1,14 @@\n A\n B\n C\n D\n E\n F\n-X\n+Y\n G\n H\n I\n J\n K\n L\n M\n",
+                $from,
+                $to,
+                107,
+            ],
+            '0 II' => [
+                "--- input.txt\n+++ output.txt\n@@ -12 +12 @@\n-X\n+Y\n",
+                "A\nB\nC\nD\nE\nF\nG\nH\nI\nJ\nK\nX\nM\n",
+                "A\nB\nC\nD\nE\nF\nG\nH\nI\nJ\nK\nY\nM\n",
+                0,
+                999,
+            ],
+            '0\' II' => [
+                "--- input.txt\n+++ output.txt\n@@ -12 +12 @@\n-X\n+Y\n",
+                "A\nB\nC\nD\nE\nF\nG\nH\nI\nJ\nK\nX\nM\nA\nA\nA\nA\nA\n",
+                "A\nB\nC\nD\nE\nF\nG\nH\nI\nJ\nK\nY\nM\nA\nA\nA\nA\nA\n",
+                0,
+                999,
+            ],
+            '0\'\' II' => [
+                "--- input.txt\n+++ output.txt\n@@ -12,2 +12,2 @@\n-X\n-M\n\\ No newline at end of file\n+Y\n+M\n",
+                "A\nB\nC\nD\nE\nF\nG\nH\nI\nJ\nK\nX\nM",
+                "A\nB\nC\nD\nE\nF\nG\nH\nI\nJ\nK\nY\nM\n",
+                0,
+            ],
+            '0\'\'\' II' => [
+                "--- input.txt\n+++ output.txt\n@@ -12,2 +12,2 @@\n-X\n-X1\n+Y\n+Y2\n",
+                "A\nB\nC\nD\nE\nF\nG\nH\nI\nJ\nK\nX\nX1\nM\nA\nA\nA\nA\nA\n",
+                "A\nB\nC\nD\nE\nF\nG\nH\nI\nJ\nK\nY\nY2\nM\nA\nA\nA\nA\nA\n",
+                0,
+                999,
+            ],
+            '1 II' => [
+                "--- input.txt\n+++ output.txt\n@@ -11,3 +11,3 @@\n K\n-X\n+Y\n M\n",
+                "A\nB\nC\nD\nE\nF\nG\nH\nI\nJ\nK\nX\nM\n",
+                "A\nB\nC\nD\nE\nF\nG\nH\nI\nJ\nK\nY\nM\n",
+                1,
+            ],
+            '5 II' => [
+                "--- input.txt\n+++ output.txt\n@@ -7,7 +7,7 @@\n G\n H\n I\n J\n K\n-X\n+Y\n M\n",
+                "A\nB\nC\nD\nE\nF\nG\nH\nI\nJ\nK\nX\nM\n",
+                "A\nB\nC\nD\nE\nF\nG\nH\nI\nJ\nK\nY\nM\n",
+                5,
+            ],
+            [
+                '--- input.txt
++++ output.txt
+@@ -1,28 +1,28 @@
+ A
+-X
++B
+ V
+-Y
++D
+ 1
+ A
+ 2
+ A
+ 3
+ A
+ 4
+ A
+ 8
+ A
+ 9
+ A
+ 5
+ A
+ A
+ A
+ A
+ A
+ A
+ A
+ A
+ A
+ A
+ A
+',
+                "A\nX\nV\nY\n1\nA\n2\nA\n3\nA\n4\nA\n8\nA\n9\nA\n5\nA\nA\nA\nA\nA\nA\nA\nA\nA\nA\nA\n",
+                "A\nB\nV\nD\n1\nA\n2\nA\n3\nA\n4\nA\n8\nA\n9\nA\n5\nA\nA\nA\nA\nA\nA\nA\nA\nA\nA\nA\n",
+                9999,
+                99999,
+            ],
+        ];
+    }
+
+    /**
+     * Returns a new instance of a Differ with a new instance of the class (DiffOutputBuilderInterface) under test.
+     *
+     * @param array $options
+     *
+     * @return Differ
+     */
+    private function getDiffer(array $options = []): Differ
+    {
+        return new Differ(new StrictUnifiedDiffOutputBuilder($options));
+    }
+}

tests/Output/UnifiedDiffOutputBuilderDataProvider.php

+<?php declare(strict_types=1);
+/*
+ * This file is part of sebastian/diff.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace SebastianBergmann\Diff\Output;
+
+/**
+ * @author SpacePossum
+ *
+ * @coversNothing
+ *
+ * @internal
+ */
+final class UnifiedDiffOutputBuilderDataProvider
+{
+    public static function provideDiffWithLineNumbers(): array
+    {
+        return [
+            'diff line 1 non_patch_compat' => [
+'--- Original
++++ New
+@@ -1 +1 @@
+-AA
++BA
+',
+                'AA',
+                'BA',
+            ],
+            'diff line +1 non_patch_compat' => [
+'--- Original
++++ New
+@@ -1 +1,2 @@
+-AZ
++
++B
+',
+                'AZ',
+                "\nB",
+            ],
+            'diff line -1 non_patch_compat' => [
+'--- Original
++++ New
+@@ -1,2 +1 @@
+-
+-AF
++B
+',
+                "\nAF",
+                'B',
+            ],
+            'II non_patch_compat' => [
+'--- Original
++++ New
+@@ -1,4 +1,2 @@
+-
+-
+ A
+ 1
+'
+                ,
+                "\n\nA\n1",
+                "A\n1",
+            ],
+            'diff last line II - no trailing linebreak non_patch_compat' => [
+'--- Original
++++ New
+@@ -5,4 +5,4 @@
+ ' . '
+ ' . '
+ ' . '
+-E
++B
+',
+                "A\n\n\n\n\n\n\nE",
+                "A\n\n\n\n\n\n\nB",
+            ],
+            [
+                "--- Original\n+++ New\n@@ -1,2 +1 @@\n \n-\n",
+                "\n\n",
+                "\n",
+            ],
+            'diff line endings non_patch_compat' => [
+                "--- Original\n+++ New\n@@ -1 +1 @@\n #Warning: Strings contain different line endings!\n-<?php\r\n+<?php\n",
+                "<?php\r\n",
+                "<?php\n",
+            ],
+        'same non_patch_compat' => [
+'--- Original
++++ New
+',
+                "AT\n",
+                "AT\n",
+            ],
+            [
+'--- Original
++++ New
+@@ -1,4 +1,4 @@
+-b
++a
+ ' . '
+ ' . '
+ ' . '
+',
+                "b\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n",
+                "a\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n",
+            ],
+            'diff line @1' => [
+'--- Original
++++ New
+@@ -1,2 +1,2 @@
+ ' . '
+-AG
++B
+',
+                "\nAG\n",
+                "\nB\n",
+            ],
+            'same multiple lines' => [
+'--- Original
++++ New
+@@ -1,4 +1,4 @@
+ ' . '
+ ' . '
+-V
++B
+ C213
+',
+                "\n\nV\nC213",
+                "\n\nB\nC213",
+            ],
+            'diff last line I' => [
+'--- Original
++++ New
+@@ -5,4 +5,4 @@
+ ' . '
+ ' . '
+ ' . '
+-E
++B
+',
+                "A\n\n\n\n\n\n\nE\n",
+                "A\n\n\n\n\n\n\nB\n",
+            ],
+            'diff line middle' => [
+'--- Original
++++ New
+@@ -5,7 +5,7 @@
+ ' . '
+ ' . '
+ ' . '
+-X
++Z
+ ' . '
+ ' . '
+ ' . '
+',
+                "A\n\n\n\n\n\n\nX\n\n\n\n\n\n\nAY",
+                "A\n\n\n\n\n\n\nZ\n\n\n\n\n\n\nAY",
+            ],
+            'diff last line III' => [
+'--- Original
++++ New
+@@ -12,4 +12,4 @@
+ ' . '
+ ' . '
+ ' . '
+-A
++B
+',
+                "A\n\n\n\n\n\n\nA\n\n\n\n\n\n\nA\n",
+                "A\n\n\n\n\n\n\nA\n\n\n\n\n\n\nB\n",
+            ],
+            [
+'--- Original
++++ New
+@@ -1,8 +1,8 @@
+ A
+-B
++B1
+ D
+ E
+ EE
+ F
+-G
++G1
+ H
+',
+                "A\nB\nD\nE\nEE\nF\nG\nH",
+                "A\nB1\nD\nE\nEE\nF\nG1\nH",
+            ],
+            [
+'--- Original
++++ New
+@@ -1,4 +1,5 @@
+ Z
++
+ a
+ b
+ c
+@@ -7,5 +8,5 @@
+ f
+ g
+ h
+-i
++x
+ j
+',
+'Z
+a
+b
+c
+d
+e
+f
+g
+h
+i
+j
+',
+'Z
+
+a
+b
+c
+d
+e
+f
+g
+h
+x
+j
+',
+            ],
+            [
+'--- Original
++++ New
+@@ -1,7 +1,5 @@
+-
+-a
++b
+ A
+-X
+-
++Y
+ ' . '
+ A
+',
+                "\na\nA\nX\n\n\nA\n",
+                "b\nA\nY\n\nA\n",
+            ],
+            [
+<<<EOF
+--- Original
++++ New
+@@ -1,7 +1,5 @@
+-
+-
+ a
+-b
++p
+ c
+ d
+ e
+@@ -9,5 +7,5 @@
+ g
+ h
+ i
+-j
++w
+ k
+
+EOF
+                ,
+                "\n\na\nb\nc\nd\ne\nf\ng\nh\ni\nj\nk\n",
+                "a\np\nc\nd\ne\nf\ng\nh\ni\nw\nk\n",
+            ],
+            [
+'--- Original
++++ New
+@@ -8,7 +8,7 @@
+ ' . '
+ ' . '
+ ' . '
+-A
++C
+ ' . '
+ ' . '
+ ' . '
+',
+                "E\n\n\n\n\nB\n\n\n\n\nA\n\n\n\n\n\n\n\n\nD1",
+                "E\n\n\n\n\nB\n\n\n\n\nC\n\n\n\n\n\n\n\n\nD1",
+            ],
+            [
+'--- Original
++++ New
+@@ -5,7 +5,7 @@
+ ' . '
+ ' . '
+ ' . '
+-Z
++U
+ ' . '
+ ' . '
+ ' . '
+@@ -12,7 +12,7 @@
+ ' . '
+ ' . '
+ ' . '
+-X
++V
+ ' . '
+ ' . '
+ ' . '
+@@ -19,7 +19,7 @@
+ ' . '
+ ' . '
+ ' . '
+-Y
++W
+ ' . '
+ ' . '
+ ' . '
+@@ -26,7 +26,7 @@
+ ' . '
+ ' . '
+ ' . '
+-W
++X
+ ' . '
+ ' . '
+ ' . '
+@@ -33,7 +33,7 @@
+ ' . '
+ ' . '
+ ' . '
+-V
++Y
+ ' . '
+ ' . '
+ ' . '
+@@ -40,4 +40,4 @@
+ ' . '
+ ' . '
+ ' . '
+-U
++Z
+',
+                "\n\n\n\n\n\n\nZ\n\n\n\n\n\n\nX\n\n\n\n\n\n\nY\n\n\n\n\n\n\nW\n\n\n\n\n\n\nV\n\n\n\n\n\n\nU\n",
+                "\n\n\n\n\n\n\nU\n\n\n\n\n\n\nV\n\n\n\n\n\n\nW\n\n\n\n\n\n\nX\n\n\n\n\n\n\nY\n\n\n\n\n\n\nZ\n",
+            ],
+            [
+<<<EOF
+--- Original
++++ New
+@@ -1,5 +1,5 @@
+ a
+-b
++p
+ c
+ d
+ e
+@@ -7,5 +7,5 @@
+ g
+ h
+ i
+-j
++w
+ k
+
+EOF
+                ,
+                "a\nb\nc\nd\ne\nf\ng\nh\ni\nj\nk\n",
+                "a\np\nc\nd\ne\nf\ng\nh\ni\nw\nk\n",
+            ],
+            [
+<<<EOF
+--- Original
++++ New
+@@ -1,4 +1,4 @@
+-A
++B
+ 1
+ 2
+ 3
+
+EOF
+                ,
+                "A\n1\n2\n3\n4\n5\n6\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1",
+                "B\n1\n2\n3\n4\n5\n6\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1",
+            ],
+            [
+                "--- Original\n+++ New\n@@ -4,7 +4,7 @@\n D\n E\n F\n-X\n+Y\n G\n H\n I\n",
+                "A\nB\nC\nD\nE\nF\nX\nG\nH\nI\nJ\nK\nL\nM\n",
+                "A\nB\nC\nD\nE\nF\nY\nG\nH\nI\nJ\nK\nL\nM\n",
+            ],
+        ];
+    }
+}

tests/Output/UnifiedDiffOutputBuilderTest.php

@@ -39,7 +39,7 @@ final class UnifiedDiffOutputBuilderTest extends TestCase
         );
     }
 
-    public function headerProvider()
+    public function headerProvider(): array
     {
         return [
             [
@@ -83,297 +83,6 @@ final class UnifiedDiffOutputBuilderTest extends TestCase
 
     public function provideDiffWithLineNumbers(): array
     {
-        return [
-            'diff line 1 non_patch_compat' => [
-                '--- Original
-+++ New
-@@ -1 +1 @@
--AA
-+BA
-',
-                'AA',
-                'BA',
-            ],
-            'diff line +1 non_patch_compat' => [
-                '--- Original
-+++ New
-@@ -1 +1,2 @@
--AZ
-+
-+B
-',
-                'AZ',
-                "\nB",
-            ],
-            'diff line -1 non_patch_compat' => [
-                '--- Original
-+++ New
-@@ -1,2 +1 @@
--
--AF
-+B
-',
-                "\nAF",
-                'B',
-            ],
-            'II non_patch_compat' => [
-                '--- Original
-+++ New
-@@ -1,2 +1,0 @@
--
--
-'
-                ,
-                "\n\nA\n1",
-                "A\n1",
-            ],
-            'diff last line II - no trailing linebreak non_patch_compat' => [
-                '--- Original
-+++ New
-@@ -8 +8 @@
--E
-+B
-',
-                "A\n\n\n\n\n\n\nE",
-                "A\n\n\n\n\n\n\nB",
-            ],
-            [
-                "--- Original\n+++ New\n@@ -1,2 +1 @@\n \n-\n",
-                "\n\n",
-                "\n",
-            ],
-            'diff line endings non_patch_compat' => [
-                "--- Original\n+++ New\n@@ -1 +1 @@\n #Warning: Strings contain different line endings!\n-<?php\r\n+<?php\n",
-                "<?php\r\n",
-                "<?php\n",
-            ],
-            'same non_patch_compat' => [
-                '--- Original
-+++ New
-',
-                "AT\n",
-                "AT\n",
-            ],
-            [
-                '--- Original
-+++ New
-@@ -1 +1 @@
--b
-+a
-',
-                "b\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n",
-                "a\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n",
-            ],
-            'diff line @1' => [
-                '--- Original
-+++ New
-@@ -1,2 +1,2 @@
- ' . '
--AG
-+B
-',
-                "\nAG\n",
-                "\nB\n",
-            ],
-            'same multiple lines' => [
-                '--- Original
-+++ New
-@@ -1,3 +1,3 @@
- ' . '
- ' . '
--V
-+B
-'
-
-                ,
-                "\n\nV\nC213",
-                "\n\nB\nC213",
-            ],
-            'diff last line I' => [
-                '--- Original
-+++ New
-@@ -8 +8 @@
--E
-+B
-',
-                "A\n\n\n\n\n\n\nE\n",
-                "A\n\n\n\n\n\n\nB\n",
-            ],
-            'diff line middle' => [
-                '--- Original
-+++ New
-@@ -8 +8 @@
--X
-+Z
-',
-                "A\n\n\n\n\n\n\nX\n\n\n\n\n\n\nAY",
-                "A\n\n\n\n\n\n\nZ\n\n\n\n\n\n\nAY",
-            ],
-            'diff last line III' => [
-                '--- Original
-+++ New
-@@ -15 +15 @@
--A
-+B
-',
-                "A\n\n\n\n\n\n\nA\n\n\n\n\n\n\nA\n",
-                "A\n\n\n\n\n\n\nA\n\n\n\n\n\n\nB\n",
-            ],
-            [
-                '--- Original
-+++ New
-@@ -1,7 +1,7 @@
- A
--B
-+B1
- D
- E
- EE
- F
--G
-+G1
-',
-                "A\nB\nD\nE\nEE\nF\nG\nH",
-                "A\nB1\nD\nE\nEE\nF\nG1\nH",
-            ],
-            [
-                '--- Original
-+++ New
-@@ -1 +1,2 @@
- Z
-+
-@@ -10 +11 @@
--i
-+x
-',
-                'Z
-a
-b
-c
-d
-e
-f
-g
-h
-i
-j',
-                'Z
-
-a
-b
-c
-d
-e
-f
-g
-h
-x
-j',
-            ],
-            [
-                '--- Original
-+++ New
-@@ -1,5 +1,3 @@
--
--a
-+b
- A
--a
--
-+b
-',
-                "\na\nA\na\n\n\nA",
-                "b\nA\nb\n\nA",
-            ],
-            [
-                <<<EOF
---- Original
-+++ New
-@@ -1,4 +1,2 @@
--
--
- a
--b
-+p
-@@ -12 +10 @@
--j
-+w
-
-EOF
-                ,
-                "\n\na\nb\nc\nd\ne\nf\ng\nh\ni\nj\nk",
-                "a\np\nc\nd\ne\nf\ng\nh\ni\nw\nk",
-            ],
-            [
-                '--- Original
-+++ New
-@@ -11 +11 @@
--A
-+C
-',
-                "E\n\n\n\n\nB\n\n\n\n\nA\n\n\n\n\n\n\n\n\nD1",
-                "E\n\n\n\n\nB\n\n\n\n\nC\n\n\n\n\n\n\n\n\nD1",
-            ],
-            [
-                '--- Original
-+++ New
-@@ -8 +8 @@
--Z
-+U
-@@ -15 +15 @@
--X
-+V
-@@ -22 +22 @@
--Y
-+W
-@@ -29 +29 @@
--W
-+X
-@@ -36 +36 @@
--V
-+Y
-@@ -43 +43 @@
--U
-+Z
-',
-                "\n\n\n\n\n\n\nZ\n\n\n\n\n\n\nX\n\n\n\n\n\n\nY\n\n\n\n\n\n\nW\n\n\n\n\n\n\nV\n\n\n\n\n\n\nU\n",
-                "\n\n\n\n\n\n\nU\n\n\n\n\n\n\nV\n\n\n\n\n\n\nW\n\n\n\n\n\n\nX\n\n\n\n\n\n\nY\n\n\n\n\n\n\nZ\n",
-            ],
-            [
-                <<<EOF
---- Original
-+++ New
-@@ -1,2 +1,2 @@
- a
--b
-+p
-@@ -10 +10 @@
--j
-+w
-
-EOF
-                ,
-                "a\nb\nc\nd\ne\nf\ng\nh\ni\nj\nk",
-                "a\np\nc\nd\ne\nf\ng\nh\ni\nw\nk",
-            ],
-            [
-                <<<EOF
---- Original
-+++ New
-@@ -1 +1 @@
--A
-+B
-
-EOF
-                ,
-                "A\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1",
-                "B\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1",
-            ],
-            [
-                "--- Original\n+++ New\n@@ -7 +7 @@\n-X\n+B\n",
-                "A\nA\nA\nA\nA\nA\nX\nC\nC\nC\nC\nC\nC",
-                "A\nA\nA\nA\nA\nA\nB\nC\nC\nC\nC\nC\nC",
-            ],
-        ];
+        return UnifiedDiffOutputBuilderDataProvider::provideDiffWithLineNumbers();
     }
 }

tests/Utils/UnifiedDiffAssertTrait.php

+<?php declare(strict_types=1);
+/*
+ * This file is part of sebastian/diff.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace SebastianBergmann\Diff\Utils;
+
+/**
+ * @author SpacePossum
+ *
+ * @internal
+ */
+trait UnifiedDiffAssertTrait
+{
+    /**
+     * @param string $diff
+     *
+     * @throws \UnexpectedValueException
+     */
+    public function assertValidUnifiedDiffFormat(string $diff)
+    {
+        if ('' === $diff) {
+            $this->addToAssertionCount(1);
+
+            return;
+        }
+
+        // test diff ends with a line break
+        $last = \substr($diff, -1);
+        if ("\n" !== $last && "\r" !== $last) {
+            throw new \UnexpectedValueException(\sprintf('Expected diff to end with a line break, got "%s".', $last));
+        }
+
+        $lines            = \preg_split('/(.*\R)/', $diff, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
+        $lineCount        = \count($lines);
+        $lineNumber       = $diffLineFromNumber       = $diffLineToNumber       = 1;
+        $fromStart        = $fromTillOffset        = $toStart        = $toTillOffset        = -1;
+        $expectHunkHeader = true;
+
+        // check for header
+        if ($lineCount > 1) {
+            $this->unifiedDiffAssertLinePrefix($lines[0], 'Line 1.');
+            $this->unifiedDiffAssertLinePrefix($lines[1], 'Line 2.');
+
+            if ('---' === \substr($lines[0], 0, 3)) {
+                if ('+++' !== \substr($lines[1], 0, 3)) {
+                    throw new \UnexpectedValueException(\sprintf("Line 1 indicates a header, so line 2 must start with \"+++\".\nLine 1: \"%s\"\nLine 2: \"%s\".", $lines[0], $lines[1]));
+                }
+
+                $this->unifiedDiffAssertHeaderLine($lines[0], '--- ', 'Line 1.');
+                $this->unifiedDiffAssertHeaderLine($lines[1], '+++ ', 'Line 2.');
+
+                $lineNumber = 3;
+            }
+        }
+
+        $endOfLineTypes = [];
+        $diffClosed     = false;
+
+        // assert format of lines, get all hunks, test the line numbers
+        for (; $lineNumber <= $lineCount; ++$lineNumber) {
+            if ($diffClosed) {
+                throw new \UnexpectedValueException(\sprintf('Unexpected line as 2 "No newline" markers have found, ". Line %d.', $lineNumber));
+            }
+
+            $line = $lines[$lineNumber - 1]; // line numbers start by 1, array index at 0
+            $type = $this->unifiedDiffAssertLinePrefix($line, \sprintf('Line %d.', $lineNumber));
+
+            if ($expectHunkHeader && '@' !== $type && '\\' !== $type) {
+                throw new \UnexpectedValueException(\sprintf('Expected hunk start (\'@\'), got "%s". Line %d.', $type, $lineNumber));
+            }
+
+            if ('@' === $type) {
+                if (!$expectHunkHeader) {
+                    throw new \UnexpectedValueException(\sprintf('Unexpected hunk start (\'@\'). Line %d.', $lineNumber));
+                }
+
+                $previousHunkFromEnd = $fromStart + $fromTillOffset;
+                $previousHunkTillEnd = $toStart + $toTillOffset;
+
+                list($fromStart, $fromTillOffset, $toStart, $toTillOffset) = $this->unifiedDiffAssertHunkHeader($line, \sprintf('Line %d.', $lineNumber));
+
+                // detect overlapping hunks
+                if ($fromStart < $previousHunkFromEnd) {
+                    throw new \UnexpectedValueException(\sprintf('Unexpected new hunk; "from" (\'-\') start overlaps previous hunk. Line %d.', $lineNumber));
+                }
+
+                if ($toStart < $previousHunkTillEnd) {
+                    throw new \UnexpectedValueException(\sprintf('Unexpected new hunk; "to" (\'+\') start overlaps previous hunk. Line %d.', $lineNumber));
+                }
+
+                /* valid states; hunks touches against each other:
+                    $fromStart === $previousHunkFromEnd
+                    $toStart === $previousHunkTillEnd
+                */
+
+                $diffLineFromNumber = $fromStart;
+                $diffLineToNumber   = $toStart;
+                $expectHunkHeader   = false;
+
+                continue;
+            }
+
+            if ('-' === $type) {
+                if (isset($endOfLineTypes['-'])) {
+                    throw new \UnexpectedValueException(\sprintf('Not expected from (\'-\'), already closed by "\\ No newline at end of file". Line %d.', $lineNumber));
+                }
+
+                ++$diffLineFromNumber;
+            } elseif ('+' === $type) {
+                if (isset($endOfLineTypes['+'])) {
+                    throw new \UnexpectedValueException(\sprintf('Not expected to (\'+\'), already closed by "\\ No newline at end of file". Line %d.', $lineNumber));
+                }
+
+                ++$diffLineToNumber;
+            } elseif (' ' === $type) {
+                if (isset($endOfLineTypes['-'])) {
+                    throw new \UnexpectedValueException(\sprintf('Not expected same (\' \'), \'-\' already closed by "\\ No newline at end of file". Line %d.', $lineNumber));
+                }
+
+                if (isset($endOfLineTypes['+'])) {
+                    throw new \UnexpectedValueException(\sprintf('Not expected same (\' \'), \'+\' already closed by "\\ No newline at end of file". Line %d.', $lineNumber));
+                }
+
+                ++$diffLineFromNumber;
+                ++$diffLineToNumber;
+            } elseif ('\\' === $type) {
+                if (!isset($lines[$lineNumber - 2])) {
+                    throw new \UnexpectedValueException(\sprintf('Unexpected "\\ No newline at end of file", it must be preceded by \'+\' or \'-\' line. Line %d.', $lineNumber));
+                }
+
+                $previousType = $this->unifiedDiffAssertLinePrefix($lines[$lineNumber - 2], \sprintf('Preceding line of "\\ No newline at end of file" of unexpected format. Line %d.', $lineNumber));
+                if (isset($endOfLineTypes[$previousType])) {
+                    throw new \UnexpectedValueException(\sprintf('Unexpected "\\ No newline at end of file", "%s" was already closed. Line %d.', $type, $lineNumber));
+                }
+
+                $endOfLineTypes[$previousType] = true;
+                $diffClosed                    = \count($endOfLineTypes) > 1;
+            } else {
+                // internal state error
+                throw new \RuntimeException(\sprintf('Unexpected line type "%s" Line %d.', $type, $lineNumber));
+            }
+
+            $expectHunkHeader =
+                $diffLineFromNumber === ($fromStart + $fromTillOffset)
+                && $diffLineToNumber === ($toStart + $toTillOffset)
+            ;
+        }
+
+        if (
+            $diffLineFromNumber !== ($fromStart + $fromTillOffset)
+            && $diffLineToNumber !== ($toStart + $toTillOffset)
+        ) {
+            throw new \UnexpectedValueException(\sprintf('Unexpected EOF, number of lines in hunk "from" (\'-\')) and "to" (\'+\') mismatched. Line %d.', $lineNumber));
+        }
+
+        if ($diffLineFromNumber !== ($fromStart + $fromTillOffset)) {
+            throw new \UnexpectedValueException(\sprintf('Unexpected EOF, number of lines in hunk "from" (\'-\')) mismatched. Line %d.', $lineNumber));
+        }
+
+        if ($diffLineToNumber !== ($toStart + $toTillOffset)) {
+            throw new \UnexpectedValueException(\sprintf('Unexpected EOF, number of lines in hunk "to" (\'+\')) mismatched. Line %d.', $lineNumber));
+        }
+
+        $this->addToAssertionCount(1);
+    }
+
+    /**
+     * @param string $line
+     * @param string $message
+     *
+     * @return string '+', '-', '@', ' ' or '\'
+     */
+    private function unifiedDiffAssertLinePrefix(string $line, string $message): string
+    {
+        $this->unifiedDiffAssertStrLength($line, 2, $message); // 2: line type indicator ('+', '-', ' ' or '\') and a line break
+        $firstChar = $line[0];
+
+        if ('+' === $firstChar || '-' === $firstChar || '@' === $firstChar || ' ' === $firstChar) {
+            return $firstChar;
+        }
+
+        if ("\\ No newline at end of file\n" === $line) {
+            return '\\';
+        }
+
+        throw new \UnexpectedValueException(\sprintf('Expected line to start with \'@\', \'-\' or \'+\', got "%s". %s', $line, $message));
+    }
+
+    private function unifiedDiffAssertStrLength(string $line, int $min, string $message)
+    {
+        $length = \strlen($line);
+        if ($length < $min) {
+            throw new \UnexpectedValueException(\sprintf('Expected string length of minimal %d, got %d. %s', $min, $length, $message));
+        }
+    }
+
+    /**
+     * Assert valid unified diff header line
+     *
+     * Samples:
+     * - "+++ from1.txt\t2017-08-24 19:51:29.383985722 +0200"
+     * - "+++ from1.txt"
+     *
+     * @param string $line
+     * @param string $start
+     * @param string $message
+     */
+    private function unifiedDiffAssertHeaderLine(string $line, string $start, string $message)
+    {
+        if (0 !== \strpos($line, $start)) {
+            throw new \UnexpectedValueException(\sprintf('Expected header line to start with "%s", got "%s". %s', $start . ' ', $line, $message));
+        }
+
+        // sample "+++ from1.txt\t2017-08-24 19:51:29.383985722 +0200\n"
+        $match = \preg_match(
+            "/^([^\t]*)(?:[\t]([\\S].*[\\S]))?\n$/",
+            \substr($line, 4), // 4 === string length of "+++ " / "--- "
+            $matches
+        );
+
+        if (1 !== $match) {
+            throw new \UnexpectedValueException(\sprintf('Header line does not match expected pattern, got "%s". %s', $line, $message));
+        }
+
+        // $file = $matches[1];
+
+        if (\count($matches) > 2) {
+            $this->unifiedDiffAssertHeaderDate($matches[2], $message);
+        }
+    }
+
+    private function unifiedDiffAssertHeaderDate(string $date, string $message)
+    {
+        // sample "2017-08-24 19:51:29.383985722 +0200"
+        $match = \preg_match(
+            '/^([\d]{4})-([01]?[\d])-([0123]?[\d])(:? [\d]{1,2}:[\d]{1,2}(?::[\d]{1,2}(:?\.[\d]+)?)?(?: ([\+\-][\d]{4}))?)?$/',
+            $date,
+            $matches
+        );
+
+        if (1 !== $match || ($matchesCount = \count($matches)) < 4) {
+            throw new \UnexpectedValueException(\sprintf('Date of header line does not match expected pattern, got "%s". %s', $date, $message));
+        }
+
+        // [$full, $year, $month, $day, $time] = $matches;
+    }
+
+    /**
+     * @param string $line
+     * @param string $message
+     *
+     * @return int[]
+     */
+    private function unifiedDiffAssertHunkHeader(string $line, string $message): array
+    {
+        if (1 !== \preg_match('#^@@ -([\d]+)((?:,[\d]+)?) \+([\d]+)((?:,[\d]+)?) @@\n$#', $line, $matches)) {
+            throw new \UnexpectedValueException(
+                \sprintf(
+                    'Hunk header line does not match expected pattern, got "%s". %s',
+                    $line,
+                    $message
+                )
+            );
+        }
+
+        return [
+            (int) $matches[1],
+            empty($matches[2]) ? 1 : (int) \substr($matches[2], 1),
+            (int) $matches[3],
+            empty($matches[4]) ? 1 : (int) \substr($matches[4], 1),
+        ];
+    }
+}

tests/Utils/UnifiedDiffAssertTraitIntegrationTest.php

+<?php declare(strict_types=1);
+/*
+ * This file is part of sebastian/diff.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace SebastianBergmann\Diff\Utils;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Process\Process;
+
+/**
+ * @author SpacePossum
+ *
+ * @requires OS Linux
+ *
+ * @coversNothing
+ *
+ * @internal
+ */
+final class UnifiedDiffAssertTraitIntegrationTest extends TestCase
+{
+    use UnifiedDiffAssertTrait;
+
+    private $filePatch;
+
+    protected function setUp()
+    {
+        $this->filePatch = __DIR__ . '/../fixtures/out/patch.txt';
+
+        $this->cleanUpTempFiles();
+    }
+
+    /**
+     * @param string $fileFrom
+     * @param string $fileTo
+     *
+     * @dataProvider provideFilePairsCases
+     */
+    public function testValidPatches(string $fileFrom, string $fileTo)
+    {
+        $command = \sprintf(
+            'diff -u %s %s > %s',
+            \escapeshellarg(\realpath($fileFrom)),
+            \escapeshellarg(\realpath($fileTo)),
+            \escapeshellarg($this->filePatch)
+        );
+
+        $p = new Process($command);
+        $p->run();
+
+        $exitCode = $p->getExitCode();
+
+        if (0 === $exitCode) {
+            // odd case when two files have the same content. Test after executing as it is more efficient than to read the files and check the contents every time.
+            $this->addToAssertionCount(1);
+
+            return;
+        }
+
+        $this->assertSame(
+            1, // means `diff` found a diff between the files we gave it
+            $exitCode,
+            \sprintf(
+                "Command exec. was not successful:\n\"%s\"\nOutput:\n\"%s\"\nStdErr:\n\"%s\"\nExit code %d.\n",
+                $command,
+                $p->getOutput(),
+                $p->getErrorOutput(),
+                $p->getExitCode()
+            )
+        );
+
+        $this->assertValidUnifiedDiffFormat(\file_get_contents($this->filePatch));
+    }
+
+    /**
+     * @return array<string, array<string, string>>
+     */
+    public function provideFilePairsCases(): array
+    {
+        $cases = [];
+
+        // created cases based on dedicated fixtures
+        $dir       = \realpath(__DIR__ . '/../fixtures/UnifiedDiffAssertTraitIntegrationTest');
+        $dirLength = \strlen($dir);
+
+        for ($i = 1;; ++$i) {
+            $fromFile = \sprintf('%s/%d_a.txt', $dir, $i);
+            $toFile   = \sprintf('%s/%d_b.txt', $dir, $i);
+
+            if (!\file_exists($fromFile)) {
+                break;
+            }
+
+            $this->assertFileExists($toFile);
+            $cases[\sprintf("Diff file:\n\"%s\"\nvs.\n\"%s\"\n", \substr(\realpath($fromFile), $dirLength), \substr(\realpath($toFile), $dirLength))] = [$fromFile, $toFile];
+        }
+
+        // create cases based on PHP files within the vendor directory for integration testing
+        $dir       = \realpath(__DIR__ . '/../../vendor');
+        $dirLength = \strlen($dir);
+
+        $fileIterator = new \RecursiveIteratorIterator(new \RecursiveDirectoryIterator($dir, \RecursiveDirectoryIterator::SKIP_DOTS));
+        $fromFile     = __FILE__;
+
+        /** @var \SplFileInfo $file */
+        foreach ($fileIterator as $file) {
+            if ('php' !== $file->getExtension()) {
+                continue;
+            }
+
+            $toFile                                                                                                                                   = $file->getPathname();
+            $cases[\sprintf("Diff file:\n\"%s\"\nvs.\n\"%s\"\n", \substr(\realpath($fromFile), $dirLength), \substr(\realpath($toFile), $dirLength))] = [$fromFile, $toFile];
+            $fromFile                                                                                                                                 = $toFile;
+        }
+
+        return $cases;
+    }
+
+    protected function tearDown()
+    {
+        $this->cleanUpTempFiles();
+    }
+
+    private function cleanUpTempFiles()
+    {
+        @\unlink($this->filePatch);
+    }
+}

tests/Utils/UnifiedDiffAssertTraitTest.php

+<?php declare(strict_types=1);
+/*
+ * This file is part of sebastian/diff.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace SebastianBergmann\Diff\Utils;
+
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @author SpacePossum
+ *
+ * @covers SebastianBergmann\Diff\UnifiedDiffAssertTrait
+ *
+ * @internal
+ */
+final class UnifiedDiffAssertTraitTest extends TestCase
+{
+    use UnifiedDiffAssertTrait;
+
+    /**
+     * @param string $diff
+     *
+     * @dataProvider provideValidCases
+     */
+    public function testValidCases(string $diff)
+    {
+        $this->assertValidUnifiedDiffFormat($diff);
+    }
+
+    public function provideValidCases(): array
+    {
+        return [
+            [
+'--- Original
++++ New
+@@ -8 +8 @@
+-Z
++U
+',
+            ],
+            [
+'--- Original
++++ New
+@@ -8 +8 @@
+-Z
++U
+@@ -15 +15 @@
+-X
++V
+',
+            ],
+            'empty diff. is valid' => [
+                '',
+            ],
+        ];
+    }
+
+    public function testNoLinebreakEnd()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Expected diff to end with a line break, got "C".', '#')));
+
+        $this->assertValidUnifiedDiffFormat("A\nB\nC");
+    }
+
+    public function testInvalidStartWithoutHeader()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote("Expected line to start with '@', '-' or '+', got \"A\n\". Line 1.", '#')));
+
+        $this->assertValidUnifiedDiffFormat("A\n");
+    }
+
+    public function testInvalidStartHeader1()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote("Line 1 indicates a header, so line 2 must start with \"+++\".\nLine 1: \"--- A\n\"\nLine 2: \"+ 1\n\".", '#')));
+
+        $this->assertValidUnifiedDiffFormat("--- A\n+ 1\n");
+    }
+
+    public function testInvalidStartHeader2()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote("Header line does not match expected pattern, got \"+++ file	X\n\". Line 2.", '#')));
+
+        $this->assertValidUnifiedDiffFormat("--- A\n+++ file\tX\n");
+    }
+
+    public function testInvalidStartHeader3()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Date of header line does not match expected pattern, got "[invalid date]". Line 1.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+"--- Original\t[invalid date]
++++ New
+@@ -1,2 +1,2 @@
+-A
++B
+ " . '
+');
+    }
+
+    public function testInvalidStartHeader4()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote("Expected header line to start with \"+++  \", got \"+++INVALID\n\". Line 2.", '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'--- Original
++++INVALID
+@@ -1,2 +1,2 @@
+-A
++B
+ ' . '
+');
+    }
+
+    public function testInvalidLine1()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote("Expected line to start with '@', '-' or '+', got \"1\n\". Line 5.", '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'--- Original
++++ New
+@@ -8 +8 @@
+-Z
+1
++U
+');
+    }
+
+    public function testInvalidLine2()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Expected string length of minimal 2, got 1. Line 4.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'--- Original
++++ New
+@@ -8 +8 @@
+
+
+');
+    }
+
+    public function testHunkInvalidFormat()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote("Hunk header line does not match expected pattern, got \"@@ INVALID -1,1 +1,1 @@\n\". Line 3.", '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'--- Original
++++ New
+@@ INVALID -1,1 +1,1 @@
+-Z
++U
+');
+    }
+
+    public function testHunkOverlapFrom()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Unexpected new hunk; "from" (\'-\') start overlaps previous hunk. Line 6.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'--- Original
++++ New
+@@ -8,1 +8,1 @@
+-Z
++U
+@@ -7,1 +9,1 @@
+-Z
++U
+');
+    }
+
+    public function testHunkOverlapTo()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Unexpected new hunk; "to" (\'+\') start overlaps previous hunk. Line 6.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'--- Original
++++ New
+@@ -8,1 +8,1 @@
+-Z
++U
+@@ -17,1 +7,1 @@
+-Z
++U
+');
+    }
+
+    public function testExpectHunk1()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Expected hunk start (\'@\'), got "+". Line 6.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'--- Original
++++ New
+@@ -8 +8 @@
+-Z
++U
++O
+');
+    }
+
+    public function testExpectHunk2()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Unexpected hunk start (\'@\'). Line 6.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'--- Original
++++ New
+@@ -8,12 +8,12 @@
+ ' . '
+ ' . '
+@@ -38,12 +48,12 @@
+');
+    }
+
+    public function testMisplacedLineAfterComments1()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Unexpected line as 2 "No newline" markers have found, ". Line 8.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'--- Original
++++ New
+@@ -8 +8 @@
+-Z
+\ No newline at end of file
++U
+\ No newline at end of file
++A
+');
+    }
+
+    public function testMisplacedLineAfterComments2()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Unexpected line as 2 "No newline" markers have found, ". Line 7.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'--- Original
++++ New
+@@ -8 +8 @@
++U
+\ No newline at end of file
+\ No newline at end of file
+\ No newline at end of file
+');
+    }
+
+    public function testMisplacedLineAfterComments3()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Unexpected line as 2 "No newline" markers have found, ". Line 7.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'--- Original
++++ New
+@@ -8 +8 @@
++U
+\ No newline at end of file
+\ No newline at end of file
++A
+');
+    }
+
+    public function testMisplacedComment()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Unexpected "\ No newline at end of file", it must be preceded by \'+\' or \'-\' line. Line 1.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'\ No newline at end of file
+');
+    }
+
+    public function testUnexpectedDuplicateNoNewLineEOF()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Unexpected "\\ No newline at end of file", "\\" was already closed. Line 8.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'--- Original
++++ New
+@@ -8,12 +8,12 @@
+ ' . '
+ ' . '
+\ No newline at end of file
+ ' . '
+\ No newline at end of file
+');
+    }
+
+    public function testFromAfterClose()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Not expected from (\'-\'), already closed by "\ No newline at end of file". Line 6.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'--- Original
++++ New
+@@ -8,12 +8,12 @@
+-A
+\ No newline at end of file
+-A
+\ No newline at end of file
+');
+    }
+
+    public function testSameAfterFromClose()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Not expected same (\' \'), \'-\' already closed by "\ No newline at end of file". Line 6.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+            '--- Original
++++ New
+@@ -8,12 +8,12 @@
+-A
+\ No newline at end of file
+ A
+\ No newline at end of file
+');
+    }
+
+    public function testToAfterClose()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Not expected to (\'+\'), already closed by "\ No newline at end of file". Line 6.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+            '--- Original
++++ New
+@@ -8,12 +8,12 @@
++A
+\ No newline at end of file
++A
+\ No newline at end of file
+');
+    }
+
+    public function testSameAfterToClose()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Not expected same (\' \'), \'+\' already closed by "\ No newline at end of file". Line 6.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+            '--- Original
++++ New
+@@ -8,12 +8,12 @@
++A
+\ No newline at end of file
+ A
+\ No newline at end of file
+');
+    }
+
+    public function testUnexpectedEOFFromMissingLines()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Unexpected EOF, number of lines in hunk "from" (\'-\')) mismatched. Line 7.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'--- Original
++++ New
+@@ -8,19 +7,2 @@
+-A
++B
+ ' . '
+');
+    }
+
+    public function testUnexpectedEOFToMissingLines()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Unexpected EOF, number of lines in hunk "to" (\'+\')) mismatched. Line 7.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'--- Original
++++ New
+@@ -8,2 +7,3 @@
+-A
++B
+ ' . '
+');
+    }
+
+    public function testUnexpectedEOFBothFromAndToMissingLines()
+    {
+        $this->expectException(\UnexpectedValueException::class);
+        $this->expectExceptionMessageRegExp(\sprintf('#^%s$#', \preg_quote('Unexpected EOF, number of lines in hunk "from" (\'-\')) and "to" (\'+\') mismatched. Line 7.', '#')));
+
+        $this->assertValidUnifiedDiffFormat(
+'--- Original
++++ New
+@@ -1,12 +1,14 @@
+-A
++B
+ ' . '
+');
+    }
+}

tests/fixtures/.editorconfig

+root = true

tests/fixtures/UnifiedDiffAssertTraitIntegrationTest/1_a.txt

+a
\ No newline at end of file