fix: emit commit_authors in commit order, not set order

action.yml

@@ -25,7 +25,7 @@ outputs:
     description: 'Path to a file containing the body to put in the Release'
     value: ${{ steps.create-tag.outputs.release_body_path }}
   commit_authors:
-    description: 'Comma-separated list of the first page of author usernames since the last Release'
+    description: 'Comma-separated author usernames since the last Release, in the order their commits appear (newest first)'
     value: ${{ steps.create-tag.outputs.commit_authors }}
 runs:
   using: 'composite'

create_tag.py

@@ -86,6 +86,25 @@ def enumerate_changes(repo, latest_tag, head_commit, max_commits=50):
             yield parsed
 
 
+def github_logins(gh_repo, author_to_sha):
+    """GitHub logins for each commit author, in the order their commits were seen.
+
+    Returns a list, not a set: the order is part of the output contract. Distinct
+    author emails can resolve to the same login, so duplicates are dropped while
+    keeping the first position.
+    """
+    logins = []
+    for email, sha in author_to_sha.items():
+        try:
+            gh_commit = gh_repo.get_commit(sha)
+        except Exception:
+            logging.debug(f"could not look up GitHub user for {email}")
+            continue
+        if gh_commit.author and gh_commit.author.login not in logins:
+            logins.append(gh_commit.author.login)
+    return logins
+
+
 def main():
     parser = argparse.ArgumentParser()
     parser.add_argument(
@@ -151,18 +170,16 @@ def main():
         )
     ]
 
-    commit_authors = set()
+    commit_authors = []
     if last_tag:
         by_type = collections.defaultdict(list)
         by_type["feat"] = []
         by_type["fix"] = []
-        change_authors = set()
 
         # email of author -> SHA of the first commit found in changes
         author_to_sha = {}
         for change in enumerate_changes(repo, last_tag, commit):
             by_type[change.type].append(f"{change.description} ({change.author})")
-            change_authors.add(change.author)
             if change.author not in author_to_sha:
                 author_to_sha[change.author] = change.sha
             for breaker in change.breaking_changes:
@@ -184,14 +201,7 @@ def main():
         if github_client is not None and author_to_sha:
             # Map commit authors to GitHub usernames via commit SHA lookup
             # it is used to add contributors to the tag
-            gh_repo = github_client.get_repo(args.repository)
-            for email, sha in author_to_sha.items():
-                try:
-                    gh_commit = gh_repo.get_commit(sha)
-                    if gh_commit.author:
-                        commit_authors.add(gh_commit.author.login)
-                except Exception:
-                    logging.debug(f"could not look up GitHub user for {email}")
+            commit_authors = github_logins(github_client.get_repo(args.repository), author_to_sha)
 
     release_body_path = f"release_notes-{new_name}.txt"
     with open(os.path.join(args.checkout_dir, release_body_path), "w") as tf:

create_tag_test.py

@@ -2,9 +2,13 @@
 from unittest import mock
 
 import git
+import github
+import github.Commit
+import github.NamedUser
+import github.Repository
 import pytest
 
-from create_tag import PRETTY_TYPES, CommitMessage, enumerate_changes
+from create_tag import PRETTY_TYPES, CommitMessage, enumerate_changes, github_logins
 
 
 def _commit(message, sha="abc123", email="dev@example.com"):
@@ -109,3 +113,63 @@ def test_enumerate_changes_without_merge_base_yields_nothing(repo):
     """No merge base (e.g. an orphan history) is swallowed, not raised."""
     orphan = repo.git.commit_tree(repo.head.commit.tree.hexsha, m="feat: orphan")
     assert list(enumerate_changes(repo, TAG, repo.commit(orphan))) == []
+
+
+def _gh_repo(sha_to_login):
+    """Repository stub whose get_commit maps a SHA to a GitHub login (None = ghost)."""
+    gh_repo = mock.create_autospec(github.Repository.Repository, instance=True)
+
+    def get_commit(sha):
+        gh_commit = mock.create_autospec(github.Commit.Commit, instance=True)
+        login = sha_to_login[sha]
+        if login is None:
+            gh_commit.author = None
+        else:
+            gh_commit.author = mock.create_autospec(github.NamedUser.NamedUser, instance=True)
+            gh_commit.author.login = login
+        return gh_commit
+
+    gh_repo.get_commit.side_effect = get_commit
+    return gh_repo
+
+
+def test_github_logins_preserves_commit_order():
+    """Order is the output contract -- #11 wanted commit order, a set gave hash order."""
+    author_to_sha = {
+        "zoe@example.com": "sha1",
+        "adam@example.com": "sha2",
+        "mia@example.com": "sha3",
+    }
+    gh_repo = _gh_repo({"sha1": "zoe-gh", "sha2": "adam-gh", "sha3": "mia-gh"})
+    assert github_logins(gh_repo, author_to_sha) == ["zoe-gh", "adam-gh", "mia-gh"]
+
+
+def test_github_logins_dedupes_keeping_first_position():
+    author_to_sha = {
+        "zoe@work.com": "sha1",
+        "adam@example.com": "sha2",
+        "zoe@personal.com": "sha3",
+    }
+    gh_repo = _gh_repo({"sha1": "zoe-gh", "sha2": "adam-gh", "sha3": "zoe-gh"})
+    assert github_logins(gh_repo, author_to_sha) == ["zoe-gh", "adam-gh"]
+
+
+def test_github_logins_skips_lookup_failures_without_losing_the_rest():
+    author_to_sha = {"a@example.com": "sha1", "b@example.com": "sha2", "c@example.com": "sha3"}
+    resolvable = _gh_repo({"sha1": "a-gh", "sha3": "c-gh"})
+
+    def get_commit(sha):
+        if sha == "sha2":
+            raise github.GithubException(404, "Not Found", None)
+        return resolvable.get_commit(sha)
+
+    gh_repo = mock.create_autospec(github.Repository.Repository, instance=True)
+    gh_repo.get_commit.side_effect = get_commit
+    assert github_logins(gh_repo, author_to_sha) == ["a-gh", "c-gh"]
+
+
+def test_github_logins_skips_commits_with_no_github_author():
+    """Unlinked email -> gh_commit.author is None; must not emit an entry."""
+    author_to_sha = {"a@example.com": "sha1", "ghost@example.com": "sha2"}
+    gh_repo = _gh_repo({"sha1": "a-gh", "sha2": None})
+    assert github_logins(gh_repo, author_to_sha) == ["a-gh"]