Add check_branch_conventions CI checks

.github/workflows/test_branch_conventions.yml

@@ -0,0 +1,35 @@
+name: Test for Malformed Commits in PR Branch
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+concurrency:
+  group: ci-${{github.workflow}}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  check-merge-commits:
+    if: github.repository == 'ArduPilot/ardupilot_wiki'
+    runs-on: ubuntu-slim
+
+    steps:
+      - name: Checkout PR branch
+        uses: actions/checkout@v6
+        with:
+          repository: ${{ github.event.pull_request.head.repo.full_name }}
+          ref: ${{ github.event.pull_request.head.ref }}
+          submodules: 'false'
+          fetch-depth: 0
+
+      - name: Fetch base branch
+        run: |
+          git remote -v
+          git remote add upstream ${{ github.event.pull_request.base.repo.clone_url }}
+          git fetch upstream ${{ github.event.pull_request.base.ref }}
+          git show upstream/${{ github.event.pull_request.base.ref }}
+
+      - name: Check branch conventions
+        shell: bash
+        run: |
+          scripts/check_branch_conventions.py --base-branch "upstream/${{ github.event.pull_request.base.ref }}"

scripts/check_branch_conventions.py

@@ -0,0 +1,152 @@
+#!/usr/bin/env python3
+
+'''
+Check PR branch commit conventions
+
+Note: this is a sideways copy of ArduPilot's
+Tools/scripts/check_branch_conventions.py which has been modified to
+remove checks that don't belong.  And, by the time you read this,
+probably adjusted to add wiki-specific checks!
+
+Validates:
+  - no merge commits
+  - no fixup! commits
+  - commit subject lines are <= 160 characters
+
+AP_FLAKE8_CLEAN
+
+'''
+
+from __future__ import annotations
+
+import argparse
+import os
+import sys
+
+import build_script_base
+
+DOCS_URL = "https://ardupilot.org/dev/docs/submitting-patches-back-to-master.html"
+MAX_SUBJECT_LEN = 160
+
+# Enable colour when attached to a terminal or running under GitHub Actions
+_colour = sys.stdout.isatty() or os.environ.get('GITHUB_ACTIONS') == 'true'
+_GREEN = '\033[32m' if _colour else ''
+_RED = '\033[31m' if _colour else ''
+_YELLOW = '\033[33m' if _colour else ''
+_RESET = '\033[0m' if _colour else ''
+
+PASS = f"{_GREEN}✓{_RESET}"
+FAIL = f"{_RED}✗{_RESET}"
+SKIP = f"{_YELLOW}~{_RESET}"
+
+
+class CheckBranchConventions(build_script_base.BuildScriptBase):
+
+    DEFAULT_UPSTREAM = "origin/master"
+
+    def __init__(self, base_branch: str | None = None) -> None:
+        super().__init__()
+        self.base_branch = base_branch
+
+    def progress_prefix(self) -> str:
+        return "CBC"
+
+    def run_git(self, args, show_output=True, source_dir=None):
+        cmd_list = ["git"] + list(args)
+        return self.run_program(
+            "SCB-GIT", cmd_list,
+            show_output=show_output, show_command=False, cwd=source_dir,
+        )
+
+    def check_merge_commits(self) -> bool:
+        merge_commits = self.run_git(
+            ["log", f"{self.base_branch}..HEAD", "--merges", "--oneline"],
+            show_output=False,
+        ).strip()
+        if merge_commits:
+            print(f"{FAIL} Merge commits are not allowed:")
+            for line in merge_commits.splitlines():
+                print(f"         {line}")
+            print(f"       See: {DOCS_URL}")
+            return False
+        print(f"{PASS} No merge commits.")
+        return True
+
+    def check_fixup_commits(self, commits: str) -> bool:
+        bad = [line for line in commits.splitlines() if "fixup!" in line]
+        if bad:
+            print(f"{FAIL} fixup! commits are not allowed:")
+            for line in bad:
+                print(f"         {line}")
+            print(f"       See: {DOCS_URL}")
+            return False
+        print(f"{PASS} No fixup! commits.")
+        return True
+
+    def check_commit_lengths(self, commits: str) -> bool:
+        ok = True
+        for line in commits.splitlines():
+            if not line.strip():
+                continue
+            if len(line) > MAX_SUBJECT_LEN:
+                print(f"{FAIL} Subject too long ({len(line)} chars, limit {MAX_SUBJECT_LEN}): {line}")
+                ok = False
+        if ok:
+            print(f"{PASS} All commit subject lines within {MAX_SUBJECT_LEN} characters.")
+        return ok
+
+    def check_author_emails(self) -> bool:
+        emails = self.run_git(
+            ["log", f"{self.base_branch}..HEAD", "--format=%ae"],
+            show_output=False,
+        ).strip()
+        bad = []
+        for email in emails.splitlines():
+            if "example.com" in email:
+                bad.append(email)
+        if bad:
+            print(f"{FAIL} Author email(s) with example.com are not allowed:")
+            for email in bad:
+                print(f"         {email}")
+            return False
+        print(f"{PASS} No unacceptable author emails.")
+        return True
+
+    def run(self) -> None:
+        if self.base_branch is None:
+            current = self.find_current_git_branch_or_sha1()
+            self.base_branch = self.find_git_branch_merge_base(current, self.DEFAULT_UPSTREAM)
+            self.progress(f"Using merge base with {self.DEFAULT_UPSTREAM}: {self.base_branch}")
+
+        commits = self.run_git(
+            ["log", f"{self.base_branch}..HEAD", "--oneline"],
+            show_output=False,
+        ).strip()
+
+        n = len(commits.splitlines()) if commits else 0
+        print(f"\nChecking {n} commit(s) since {self.base_branch}...\n")
+
+        results = [
+            self.check_merge_commits(),
+            self.check_fixup_commits(commits),
+            self.check_commit_lengths(commits),
+            self.check_author_emails(),
+        ]
+
+        failures = results.count(False)
+        print(f"\n{'All checks passed.' if not failures else f'{failures} check(s) failed.'}")
+        sys.exit(0 if all(results) else 1)
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(
+        description="Check PR branch commit conventions and markdown linting",
+    )
+    parser.add_argument(
+        "--base-branch",
+        default=None,
+        help="Upstream base branch or commit to compare against "
+             "(default: merge base of HEAD with origin/master)",
+    )
+    args = parser.parse_args()
+    CheckBranchConventions(args.base_branch).run()