tests: skip rlib tests if the "nm" tool is missing

Closes: #837742

tests/comparators/test_rlib.py

@@ -25,7 +25,7 @@ from diffoscope.comparators.ar import ArFile
 from diffoscope.comparators.utils import diff_ignore_line_numbers
 
 from utils import skip_unless_tools_exist, skip_unless_tool_is_older_than, \
-    data, load_fixture, assert_non_existing
+    skip_unless_tools_exist, data, load_fixture, assert_non_existing
 
 rlib1 = load_fixture(data('test1.rlib'))
 rlib2 = load_fixture(data('test2.rlib'))
@@ -44,21 +44,25 @@ def test_no_differences(rlib1):
 def differences(rlib1, rlib2):
     return rlib1.compare(rlib2).details
 
+@skip_unless_tools_exist('nm')
 def test_num_items(differences):
     assert len(differences) == 4
 
+@skip_unless_tools_exist('nm')
 def test_item0_armap(differences):
     assert differences[0].source1 == 'nm -s {}'
     assert differences[0].source2 == 'nm -s {}'
     expected_diff = open(data('rlib_armap_expected_diff')).read()
     assert differences[0].unified_diff == expected_diff
 
+@skip_unless_tools_exist('nm')
 def test_item1_elf(differences):
     assert differences[1].source1 == 'alloc_system-d16b8f0e.0.o'
     assert differences[1].source2 == 'alloc_system-d16b8f0e.0.o'
     expected_diff = open(data('rlib_elf_expected_diff')).read()
     assert differences[1].details[0].unified_diff == expected_diff
 
+@skip_unless_tools_exist('nm')
 def test_item2_rust_metadata_bin(differences):
     assert differences[2].source1 == 'rust.metadata.bin'
     assert differences[2].source2 == 'rust.metadata.bin'
@@ -72,5 +76,6 @@ def test_item3_deflate_llvm_bitcode(differences):
     actual_diff = differences[3].details[0].details[1].unified_diff
     assert diff_ignore_line_numbers(actual_diff) == diff_ignore_line_numbers(expected_diff)
 
+@skip_unless_tools_exist('nm')
 def test_compare_non_existing(monkeypatch, rlib1):
     assert_non_existing(monkeypatch, rlib1)