GitCommitBear.py: Detect revert commits

bears/vcs/git/GitCommitBear.py

@@ -67,6 +67,12 @@ def check_prerequisites(cls):
         else:
             return True
 
+    @classmethod
+    def get_revert_checks_metadata(cls):
+        return FunctionMetadata.from_function(
+            cls.check_revert,
+            omit={'self', 'shortlog', 'body'})
+
     @classmethod
     def get_shortlog_checks_metadata(cls):
         return FunctionMetadata.from_function(
@@ -91,6 +97,7 @@ def get_metadata(cls):
             FunctionMetadata.from_function(
                 cls.run,
                 omit={'self', 'dependency_results'}),
+            cls.get_revert_checks_metadata(),
             cls.get_shortlog_checks_metadata(),
             cls.get_body_checks_metadata(),
             cls.get_issue_checks_metadata())
@@ -141,6 +148,10 @@ def run(self,
                 yield Result(self, 'HEAD commit has no message.')
             return
 
+        yield from self.check_revert(
+            shortlog,
+            body,
+            **self.get_revert_checks_metadata().filter_parameters(kwargs))
         yield from self.check_shortlog(
             shortlog,
             **self.get_shortlog_checks_metadata().filter_parameters(kwargs))
@@ -151,6 +162,59 @@ def run(self,
             body,
             **self.get_issue_checks_metadata().filter_parameters(kwargs))
 
+    def check_revert(self, shortlog, body,
+                     allow_revert_commits_without_reason: bool = False):
+        """
+        Validates revert commits.
+
+        :param shortlog:
+            The shortlog message string.
+        :param body:
+            The body of the commit message of HEAD.
+        :param allow_revert_commits_without_reason:
+            Whether reason is needed for revert commits.
+        """
+        if not shortlog.startswith('Revert '):
+            return
+
+        shortlog_start_index = shortlog.find('"')
+        shortlog_end_index = shortlog.rfind('"')
+        reverted_shortlog = shortlog[shortlog_start_index +
+                                     1: shortlog_end_index]
+
+        body = body.strip('\n')
+        blankline = body.find('\n\n')
+        headline = body[:blankline] if blankline != -1 else body
+
+        if not headline.startswith('This reverts '):
+            yield Result(self, 'Invalid revert commit.')
+            return
+
+        sha_regex = re.compile(r'([0-9a-f]{40})')
+        commit_sha = re.findall(sha_regex, headline)[0]
+        command = ('git log -n 1 ' +
+                   str(commit_sha) + ' --pretty=%B')
+        previous_commit_stdout, previous_commit_stderr = run_shell_command(
+            command)
+
+        if previous_commit_stderr:
+            yield Result(self, 'Invalid sha for reverted commit.')
+            return
+
+        previous_commit_stdout = previous_commit_stdout.rstrip('\n')
+        position = previous_commit_stdout.find('\n')
+        old_shortlog = previous_commit_stdout[:position] if position != - \
+            1 else previous_commit_stdout
+
+        if old_shortlog != reverted_shortlog:
+            yield Result(self, 'Shortlog of revert commit does '
+                         'not match the original commit.')
+
+        reason = body[blankline+1:] if blankline != -1 else ''
+
+        if not allow_revert_commits_without_reason and len(reason) == 0:
+            yield Result(self, 'Revert commit does not have a reason.')
+
     def check_shortlog(self, shortlog,
                        shortlog_length: int = 50,
                        shortlog_regex: str = '',

tests/vcs/git/GitCommitBearTest.py

@@ -95,11 +95,13 @@ def test_get_metadata(self):
         metadata = GitCommitBear.get_metadata()
         self.assertEqual(
             metadata.name,
-            "<Merged signature of 'run', 'check_shortlog', 'check_body'"
-            ", 'check_issue_reference'>")
+            "<Merged signature of 'run', 'check_revert', 'check_shortlog'"
+            ", 'check_body', 'check_issue_reference'>")
 
         # Test if at least one parameter of each signature is used.
         self.assertIn('allow_empty_commit_message', metadata.optional_params)
+        self.assertIn('allow_revert_commits_without_reason',
+                      metadata.optional_params)
         self.assertIn('shortlog_length', metadata.optional_params)
         self.assertIn('body_line_length', metadata.optional_params)
         self.assertIn('body_close_issue', metadata.optional_params)
@@ -125,6 +127,68 @@ def test_empty_message(self):
                          [])
         self.assert_no_msgs()
 
+    def test_revert_checks(self):
+        self.git_commit('Test commit')
+        commit_hash, _ = run_shell_command('git rev-parse HEAD')
+        self.git_commit('Revert "Test commit"\n\n'
+                        'Abcdef blablabla commit ' + str(commit_hash) + '\n\n'
+                        'Reason for the revert commit is explained here.\n')
+        self.assertEqual(self.run_uut(),
+                         ['Invalid revert commit.'])
+        self.assert_no_msgs()
+
+        self.git_commit('Test commit1\n\n'
+                        'This is body of test commit1\n')
+        commit_hash, _ = run_shell_command('git rev-parse HEAD')
+
+        self.git_commit('Revert "Another Test commit2"\n\n'
+                        'This reverts commit ' + str(commit_hash) + '\n\n'
+                        'Reason for the revert commit is explained here.\n')
+        self.assertEqual(
+            self.run_uut(),
+            ['Shortlog of revert commit does not match the original commit.'])
+        self.assert_no_msgs()
+
+        self.git_commit('Test commit3')
+        commit_hash, _ = run_shell_command('git rev-parse HEAD')
+        self.git_commit('Revert "Test commit3"\n\n'
+                        'This reverts commit ' + str(commit_hash) + '\n\n')
+        self.assertEqual(self.run_uut(),
+                         ['Revert commit does not have a reason.'])
+        self.assert_no_msgs()
+
+        self.git_commit('Revert "Test commit3"\n\n'
+                        'This reverts commit ' + str(commit_hash) + '\n\n')
+        self.assertEqual(
+            self.run_uut(allow_revert_commits_without_reason=True),
+            [])
+        self.assert_no_msgs()
+
+        self.git_commit('Revert "Test commit3"\n\n'
+                        'This reverts commit ' + str(commit_hash) + '\n\n'
+                        'Reason for the revert commit is explained here.\n')
+        self.assertEqual(self.run_uut(), [])
+        self.assert_no_msgs()
+
+        invalid_commit_hash = '0000000000000000000000000000000000000000'
+        self.git_commit('Revert "Test commit3"\n\n'
+                        'This reverts commit ' + invalid_commit_hash + '\n\n'
+                        'Reason for the revert commit is explained here.\n')
+        self.assertEqual(self.run_uut(),
+                         ['Invalid sha for reverted commit.'])
+        self.assert_no_msgs()
+
+        self.git_commit('Test commit4\n\n'
+                        'This is body of test commit1\n')
+        commit_hash, _ = run_shell_command('git rev-parse HEAD')
+        self.git_commit('Revert "Another Test commit5"\n\n'
+                        'This reverts commit ' + str(commit_hash) + '\n\n'
+                        'Reason for the revert commit is explained here.\n')
+        self.assertEqual(
+            self.run_uut(),
+            ['Shortlog of revert commit does not match the original commit.'])
+        self.assert_no_msgs()
+
     @unittest.mock.patch('bears.vcs.git.GitCommitBear.run_shell_command',
                          return_value=('one-liner-message\n', ''))
     def test_pure_oneliner_message(self, patch):