Test content generation with git diff return value

Assert equal dirs by diff return value, rather than diff output.
This prevents tests from failing when file contents are the same but the
file modes are different.

Fix #3042

pelican/tests/test_pelican.py

@@ -35,6 +35,22 @@ def recursiveDiff(dcmp):
     return diff
 
 
+def assertDirsEqual(left_path, right_path):
+    """
+    Raise AssertionError if files in paths differ (ignoring whitespace).
+    """
+    proc = subprocess.Popen(
+        ['git', '--no-pager', 'diff', '--no-ext-diff', '--exit-code',
+         '-w', left_path, right_path],
+        stdout=subprocess.PIPE,
+        stderr=subprocess.STDOUT
+    )
+
+    out = proc.communicate()
+    if proc.returncode:
+        assert not out, out
+
+
 class TestPelican(LoggedTestCase):
     # general functional testing for pelican. Basically, this test case tries
     # to run pelican in different situations and see how it behaves
@@ -54,29 +70,6 @@ def tearDown(self):
         locale.setlocale(locale.LC_ALL, self.old_locale)
         super().tearDown()
 
-    def assertDirsEqual(self, left_path, right_path):
-        out, err = subprocess.Popen(
-            ['git', '--no-pager', 'diff', '--no-ext-diff', '--exit-code',
-             '-w', left_path, right_path],
-            stdout=subprocess.PIPE,
-            stderr=subprocess.PIPE
-        ).communicate()
-
-        def ignorable_git_crlf_errors(line):
-            # Work around for running tests on Windows
-            for msg in [
-                    "LF will be replaced by CRLF",
-                    "CRLF will be replaced by LF",
-                    "The file will have its original line endings"]:
-                if msg in line:
-                    return True
-            return False
-        if err:
-            err = '\n'.join([line for line in err.decode('utf8').splitlines()
-                             if not ignorable_git_crlf_errors(line)])
-        assert not out, out
-        assert not err, err
-
     def test_order_of_generators(self):
         # StaticGenerator must run last, so it can identify files that
         # were skipped by the other generators, and so static files can
@@ -103,8 +96,7 @@ def test_basic_generation_works(self):
         })
         pelican = Pelican(settings=settings)
         mute(True)(pelican.run)()
-        self.assertDirsEqual(
-            self.temp_path, os.path.join(OUTPUT_PATH, 'basic'))
+        assertDirsEqual(self.temp_path, os.path.join(OUTPUT_PATH, 'basic'))
         self.assertLogCountEqual(
             count=1,
             msg="Unable to find.*skipping url replacement",
@@ -120,8 +112,7 @@ def test_custom_generation_works(self):
         })
         pelican = Pelican(settings=settings)
         mute(True)(pelican.run)()
-        self.assertDirsEqual(
-            self.temp_path, os.path.join(OUTPUT_PATH, 'custom'))
+        assertDirsEqual(self.temp_path, os.path.join(OUTPUT_PATH, 'custom'))
 
     @unittest.skipUnless(locale_available('fr_FR.UTF-8') or
                          locale_available('French'), 'French locale needed')
@@ -140,8 +131,8 @@ def test_custom_locale_generation_works(self):
         })
         pelican = Pelican(settings=settings)
         mute(True)(pelican.run)()
-        self.assertDirsEqual(
-            self.temp_path, os.path.join(OUTPUT_PATH, 'custom_locale'))
+        assertDirsEqual(self.temp_path,
+                        os.path.join(OUTPUT_PATH, 'custom_locale'))
 
     def test_theme_static_paths_copy(self):
         # the same thing with a specified set of settings should work