Automerge PR labeled with "automerge". (#146)

Merge the PR if:
- PR has "awaiting merge" and "automerge" labels, and
- all CI status checks have passed.

It will:
- replace `#` with `GH-`
- get the commit message from PR title and description

Closes python/bedevere#14
Closes python/core-workflow#29

miss_islington/backport_pr.py

@@ -42,7 +42,7 @@ async def backport_pr(event, gh, *args, **kwargs):
             if random.random() < 0.1:
                 easter_egg = EASTER_EGG
             thanks_to = ""
-            if created_by == merged_by:
+            if created_by == merged_by or merged_by == "miss-islington":
                 thanks_to = f"Thanks @{created_by} for the PR 🌮🎉."
             else:
                 thanks_to = f"Thanks @{created_by} for the PR, and @{merged_by} for merging it 🌮🎉."

miss_islington/status_change.py

@@ -14,23 +14,44 @@ async def check_status(event, gh, *args, **kwargs):
     """
     Check the state change
     """
+    sha = event.data["sha"]
+
     if (
         event.data["commit"].get("committer")
         and event.data["commit"]["committer"]["login"] == "miss-islington"
     ):
-        sha = event.data["sha"]
         await check_ci_status_and_approval(gh, sha, leave_comment=True)
+    else:
+        pr_for_commit = await util.get_pr_for_commit(gh, sha)
+        if pr_for_commit:
+            pr_labels = pr_for_commit["labels"]
+            if util.pr_is_automerge(pr_labels) and util.pr_is_awaiting_merge(pr_labels):
+                await check_ci_status_and_approval(
+                    gh, sha, leave_comment=True, is_automerge=True
+                )
 
 
 @router.register("pull_request", action="labeled")
 async def pr_reviewed(event, gh, *args, **kwargs):
-    if event.data["pull_request"]["user"]["login"] == "miss-islington":
-        if util.pr_is_awaiting_merge(event.data["pull_request"]["labels"]):
-            sha = event.data["pull_request"]["head"]["sha"]
-            await check_ci_status_and_approval(gh, sha)
+
+    pr_labels = event.data["pull_request"]["labels"]
+
+    if util.pr_is_automerge(pr_labels) and util.pr_is_awaiting_merge(pr_labels):
+        sha = event.data["pull_request"]["head"]["sha"]
+
+        await check_ci_status_and_approval(gh, sha, is_automerge=True)
+    elif event.data["pull_request"]["user"][
+        "login"
+    ] == "miss-islington" and util.pr_is_awaiting_merge(
+        event.data["pull_request"]["labels"]
+    ):
+        sha = event.data["pull_request"]["head"]["sha"]
+        await check_ci_status_and_approval(gh, sha)
 
 
-async def check_ci_status_and_approval(gh, sha, leave_comment=False):
+async def check_ci_status_and_approval(
+    gh, sha, leave_comment=False, is_automerge=False
+):
 
     result = await gh.getitem(f"/repos/python/cpython/commits/{sha}/status")
     all_ci_status = [status["state"] for status in result["statuses"]]
@@ -40,56 +61,66 @@ async def check_ci_status_and_approval(gh, sha, leave_comment=False):
         "pending" not in all_ci_status
         and "continuous-integration/travis-ci/pr" in all_ci_context
     ):
-
-        prs_for_commit = await gh.getitem(f'/search/issues?q=type:pr+repo:python/cpython+sha:{sha}')
-        if prs_for_commit["total_count"] > 0:  # there should only be one
-            pr_for_commit = prs_for_commit["items"][0]
+        pr_for_commit = await util.get_pr_for_commit(gh, sha)
+        if pr_for_commit:
             pr_number = pr_for_commit["number"]
             normalized_pr_title = util.normalize_title(
                 pr_for_commit["title"], pr_for_commit["body"]
             )
 
             title_match = TITLE_RE.match(normalized_pr_title)
-            if title_match:
+            if title_match or is_automerge:
                 if leave_comment:
-                    original_pr_number = title_match.group("pr")
-                    original_pr_url = (
-                        f"/repos/python/cpython/pulls/{original_pr_number}"
-                    )
-                    original_pr_result = await gh.getitem(original_pr_url)
-                    pr_author = original_pr_result["user"]["login"]
-                    committer = original_pr_result["merged_by"]["login"]
+                    if is_automerge:
+                        participants = await util.get_gh_participants(gh, pr_number)
+                    else:
+                        original_pr_number = title_match.group("pr")
+                        participants = await util.get_gh_participants(
+                            gh, original_pr_number
+                        )
 
-                    participants = util.get_participants(pr_author, committer)
                     emoji = "✅" if result["state"] == "success" else "❌"
 
                     await util.leave_comment(
                         gh,
                         pr_number=pr_number,
-                        message=f"{participants}: Backport status check is done, and it's a {result['state']} {emoji} .",
+                        message=f"{participants}: Status check is done, and it's a {result['state']} {emoji} .",
                     )
-
                 if result["state"] == "success":
-                    pr = await gh.getitem(
-                        f"/repos/python/cpython/pulls/{pr_number}"
-                    )
-                    if util.pr_is_awaiting_merge(pr["labels"]):
-                        await merge_pr(gh, pr_number, sha)
 
+                    if util.pr_is_awaiting_merge(pr_for_commit["labels"]):
+                        await merge_pr(
+                            gh, pr_for_commit, sha, is_automerge=is_automerge
+                        )
 
-async def merge_pr(gh, pr_number, sha):
+
+async def merge_pr(gh, pr, sha, is_automerge=False):
+    pr_number = pr["number"]
     async for commit in gh.getiter(f"/repos/python/cpython/pulls/{pr_number}/commits"):
         if commit["sha"] == sha:
-            pr_commit_msg = commit["commit"]["message"].split("\n")
-
-            cleaned_up_title = f"{pr_commit_msg[0]}"
-            await gh.put(
-                f"/repos/python/cpython/pulls/{pr_number}/merge",
-                data={
-                    "commit_title": cleaned_up_title,
-                    "commit_message": "\n".join(pr_commit_msg[1:]),
-                    "sha": sha,
-                    "merge_method": "squash",
-                },
-            )
+            if is_automerge:
+                pr_commit_msg = pr["body"]
+                pr_title = f"{pr['title']} (GH-{pr_number})"
+                await gh.put(
+                    f"/repos/python/cpython/pulls/{pr_number}/merge",
+                    data={
+                        "commit_title": pr_title,
+                        "commit_message": pr_commit_msg,
+                        "sha": sha,
+                        "merge_method": "squash",
+                    },
+                )
+            else:
+                pr_commit_msg = commit["commit"]["message"].split("\n")
+
+                cleaned_up_title = f"{pr_commit_msg[0]}"
+                await gh.put(
+                    f"/repos/python/cpython/pulls/{pr_number}/merge",
+                    data={
+                        "commit_title": cleaned_up_title,
+                        "commit_message": "\n".join(pr_commit_msg[1:]),
+                        "sha": sha,
+                        "merge_method": "squash",
+                    },
+                )
             break

miss_islington/util.py

@@ -7,6 +7,9 @@
 from gidgethub import sansio
 
 
+AUTOMERGE_LABEL = ":robot: automerge"
+
+
 def comment_on_pr(issue_number, message):
     """
     Leave a comment on a PR/Issue
@@ -66,9 +69,27 @@ def is_cpython_repo():
     return True
 
 
+async def get_gh_participants(gh, pr_number):
+    pr_url = f"/repos/python/cpython/pulls/{pr_number}"
+    pr_result = await gh.getitem(pr_url)
+    created_by = pr_result["user"]["login"]
+
+    merged_by = None
+    if pr_result["merged_by"] and pr_result["merged_by"]["login"] != "miss-islington":
+        merged_by = pr_result["merged_by"]["login"]
+
+    participants = ""
+    if created_by == merged_by or merged_by is None:
+        participants = f"@{created_by}"
+    else:
+        participants = f"@{created_by} and @{merged_by}"
+
+    return participants
+
+
 def get_participants(created_by, merged_by):
     participants = ""
-    if created_by == merged_by:
+    if created_by == merged_by or merged_by == "miss-islington":
         participants = f"@{created_by}"
     else:
         participants = f"@{created_by} and @{merged_by}"
@@ -113,3 +134,20 @@ def pr_is_awaiting_merge(pr_labels):
         if label["name"] == "awaiting merge":
             return True
     return False
+
+
+def pr_is_automerge(pr_labels):
+    for label in pr_labels:
+        if label["name"] == AUTOMERGE_LABEL:
+            return True
+    return False
+
+
+async def get_pr_for_commit(gh, sha):
+    prs_for_commit = await gh.getitem(
+        f"/search/issues?q=type:pr+repo:python/cpython+sha:{sha}"
+    )
+    if prs_for_commit["total_count"] > 0:  # there should only be one
+        pr_for_commit = prs_for_commit["items"][0]
+        return pr_for_commit
+    return None