tests: Smoke test --progress output.

Signed-off-by: Chris Lamb <lamby@debian.org>

tests/test_progress.py

+# -*- coding: utf-8 -*-
+#
+# diffoscope: in-depth comparison of files, archives, and directories
+#
+# Copyright © 2017 Chris Lamb <lamby@debian.org>
+#
+# diffoscope is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# diffoscope is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with diffoscope.  If not, see <https://www.gnu.org/licenses/>.
+
+import os
+import pytest
+
+from diffoscope.main import main
+
+TEST_TAR1_PATH = os.path.join(os.path.dirname(__file__), 'data', 'test1.tar')
+TEST_TAR2_PATH = os.path.join(os.path.dirname(__file__), 'data', 'test2.tar')
+
+
+def run(capsys, *args):
+    with pytest.raises(SystemExit) as exc:
+        main(args)
+
+    out, err = capsys.readouterr()
+
+    return exc.value.code, out, err
+
+def test_progress(capsys):
+    ret, _, err = run(capsys, TEST_TAR1_PATH, TEST_TAR2_PATH, '--progress')
+
+    assert ret == 1
+    assert "ETA" in err