Fix some tests that were failing in Docker

tests/conftest.py

@@ -148,12 +148,14 @@ def run_ocrmypdf(input_file, output_file, *args, universal_newlines=True):
     )
 
     # Tell subprocess where to find coverage.py configuration
-    # This has no effect except when coverage is running
+    # This has no unless except when coverage is running
     # Details: https://coverage.readthedocs.io/en/coverage-5.0/subprocess.html
     coverage_rc = Path(__file__).parent.parent / '.coveragerc'
-    assert coverage_rc.exists()
     env = os.environ.copy()
-    env['COVERAGE_PROCESS_START'] = os.fspath(coverage_rc)
+    if coverage_rc.exists():
+        env['COVERAGE_PROCESS_START'] = os.fspath(coverage_rc)
+    elif not running_in_docker():
+        assert False, "could not find .coveragerc"
 
     p = run(
         p_args,

tests/test_helpers.py

@@ -64,6 +64,11 @@ def test_deprecated():
         assert old_function() == 42
 
 
+skipif_docker = pytest.mark.skipif(
+    pytest.helpers.running_in_docker(), reason="fails on Docker"
+)
+
+
 class TestFileIsWritable:
     @pytest.fixture
     def non_existent(self, tmp_path):
@@ -83,6 +88,7 @@ class TestFileIsWritable:
         loop.symlink_to(loop)
         assert not helpers.is_file_writable(loop)
 
+    @skipif_docker
     def test_chmod(self, basic_file):
         assert helpers.is_file_writable(basic_file)
         basic_file.chmod(0o400)

tests/test_main.py

@@ -279,7 +279,9 @@ def test_input_file_not_found(caplog, no_outpdf):
     assert input_file in caplog.text
 
 
-@pytest.mark.skipif(os.name == 'nt', reason="chmod")
+@pytest.mark.skipif(
+    os.name == 'nt' or pytest.helpers.running_in_docker(), reason="chmod"
+)
 def test_input_file_not_readable(caplog, resources, outdir, no_outpdf):
     input_file = outdir / 'trivial.pdf'
     shutil.copy(resources / 'trivial.pdf', input_file)