[changelog] An option to show only merge commits. (#297)

* [capability][changelog] An option to show only merge commits.

Cleaner logic (address https://github.com/plusone-robotics/catkin_pkg/pull/1/files#r454458598, and https://github.com/ros-infrastructure/catkin_pkg/pull/297/files#r496031733).

* [gen_changelog] Handling mutually exclusive args.
[gen_changelog] Replace custom logic with add_mutually_exclusive_group (address #297 (comment)).

src/catkin_pkg/changelog_generator.py

@@ -48,24 +48,24 @@
 FORTHCOMING_LABEL = 'Forthcoming'
 
 
-def get_all_changes(vcs_client, skip_merges=False):
+def get_all_changes(vcs_client, skip_merges=False, only_merges=False):
     tags = _get_version_tags(vcs_client)
 
     # query all log entries per tag range
     tag2log_entries = {}
     previous_tag = Tag(None)
     for tag in sorted_tags(tags):
         log_entries = vcs_client.get_log_entries(
-            from_tag=previous_tag.name, to_tag=tag.name, skip_merges=skip_merges)
+            from_tag=previous_tag.name, to_tag=tag.name, skip_merges=skip_merges, only_merges=only_merges)
         tag2log_entries[previous_tag] = log_entries
         previous_tag = tag
     log_entries = vcs_client.get_log_entries(
-        from_tag=previous_tag.name, to_tag=None, skip_merges=skip_merges)
+        from_tag=previous_tag.name, to_tag=None, skip_merges=skip_merges, only_merges=only_merges)
     tag2log_entries[previous_tag] = log_entries
     return tag2log_entries
 
 
-def get_forthcoming_changes(vcs_client, skip_merges=False):
+def get_forthcoming_changes(vcs_client, skip_merges=False, only_merges=False):
     tags = _get_version_tags(vcs_client)
     latest_tag_name = _get_latest_version_tag_name(vcs_client)
 
@@ -79,7 +79,7 @@ def get_forthcoming_changes(vcs_client, skip_merges=False):
         # ignore non-forthcoming log entries but keep version to identify injection point of forthcoming
         tag2log_entries[tag] = None
     log_entries = vcs_client.get_log_entries(
-        from_tag=from_tag.name, to_tag=to_tag.name, skip_merges=skip_merges)
+        from_tag=from_tag.name, to_tag=to_tag.name, skip_merges=skip_merges, only_merges=only_merges)
     tag2log_entries[from_tag] = log_entries
     return tag2log_entries
 

src/catkin_pkg/changelog_generator_vcs.py

@@ -88,7 +88,7 @@ def get_tags(self):
     def get_latest_tag_name(self):
         raise NotImplementedError()
 
-    def get_log_entries(self, from_tag, to_tag, skip_merges=False):
+    def get_log_entries(self, from_tag, to_tag, skip_merges=False, only_merges=False):
         raise NotImplementedError()
 
     def replace_repository_references(self, line):
@@ -179,14 +179,18 @@ def get_latest_tag_name(self):
         tag_name = result_describe['output']
         return tag_name
 
-    def get_log_entries(self, from_tag, to_tag, skip_merges=False):
+    def get_log_entries(self, from_tag, to_tag, skip_merges=False, only_merges=False):
         # query all hashes in the range
         cmd = [self._executable, 'log']
         if from_tag or to_tag:
             cmd.append('%s%s' % ('%s..' % to_tag if to_tag else '', from_tag if from_tag else ''))
         cmd.append('--format=format:%H')
+        if skip_merges and only_merges:
+            raise RuntimeError('Both "skip_merges" and "only_merges" are set to True, which contradicts.')
         if skip_merges:
             cmd.append('--no-merges')
+        if only_merges:
+            cmd.append('--merges')
         result = self._run_command(cmd)
         if result['returncode']:
             raise RuntimeError('Could not fetch commit hashes:\n%s' % result['output'])
@@ -348,7 +352,7 @@ def get_latest_tag_name(self):
             raise RuntimeError('Could not find latest tagn')
         return tag_name
 
-    def get_log_entries(self, from_tag, to_tag, skip_merges=False):
+    def get_log_entries(self, from_tag, to_tag, skip_merges=False, only_merges=False):
         # query all hashes in the range
         # ascending chronological order since than it is easier to handle empty tag names
         revrange = '%s:%s' % ((to_tag if to_tag else ''), (from_tag if from_tag else 'tip'))

src/catkin_pkg/cli/generate_changelog.py

@@ -40,16 +40,20 @@ def prompt_continue(msg, default):
 
 def main(sysargs=None):
     parser = argparse.ArgumentParser(description='Generate a REP-0132 %s' % CHANGELOG_FILENAME)
+    group_merge = parser.add_mutually_exclusive_group()
     parser.add_argument(
         '-a', '--all', action='store_true', default=False,
         help='Generate changelog for all versions instead of only the forthcoming one (only supported when no changelog file exists yet)')
+    group_merge.add_argument(
+        '--only-merges', action='store_true', default=False,
+        help='Only add merge commits to the changelog')
     parser.add_argument(
         '--print-root', action='store_true', default=False,
         help='Output changelog content to the console as if there would be only one package in the root of the repository')
     parser.add_argument(
         '--skip-contributors', action='store_true', default=False,
         help='Skip adding the list of contributors to the changelog')
-    parser.add_argument(
+    group_merge.add_argument(
         '--skip-merges', action='store_true', default=False,
         help='Skip adding merge commits to the changelog')
     parser.add_argument(
@@ -66,11 +70,11 @@ def main(sysargs=None):
         # printing status messages to stderr to allow piping the changelog to a file
         if args.all:
             print('Querying all tags and commit information...', file=sys.stderr)
-            tag2log_entries = get_all_changes(vcs_client, skip_merges=args.skip_merges)
+            tag2log_entries = get_all_changes(vcs_client, skip_merges=args.skip_merges, only_merges=args.only_merges)
             print('Generating changelog output with all versions...', file=sys.stderr)
         else:
             print('Querying commit information since latest tag...', file=sys.stderr)
-            tag2log_entries = get_forthcoming_changes(vcs_client, skip_merges=args.skip_merges)
+            tag2log_entries = get_forthcoming_changes(vcs_client, skip_merges=args.skip_merges, only_merges=args.only_merges)
             print('Generating changelog files with forthcoming version...', file=sys.stderr)
         print('', file=sys.stderr)
         data = generate_changelog_file('repository-level', tag2log_entries, vcs_client=vcs_client)
@@ -106,12 +110,12 @@ def main(sysargs=None):
 
     if args.all:
         print('Querying all tags and commit information...')
-        tag2log_entries = get_all_changes(vcs_client, skip_merges=args.skip_merges)
+        tag2log_entries = get_all_changes(vcs_client, skip_merges=args.skip_merges, only_merges=args.only_merges)
         print('Generating changelog files with all versions...')
         generate_changelogs(base_path, packages, tag2log_entries, logger=logging, vcs_client=vcs_client, skip_contributors=args.skip_contributors)
     else:
         print('Querying commit information since latest tag...')
-        tag2log_entries = get_forthcoming_changes(vcs_client, skip_merges=args.skip_merges)
+        tag2log_entries = get_forthcoming_changes(vcs_client, skip_merges=args.skip_merges, only_merges=args.only_merges)
         # separate packages with/without a changelog file
         packages_without = {pkg_path: package for pkg_path, package in packages.items() if package.name in missing_changelogs}
         if packages_without: