build: commit linting in ci (#21)

* build: commit-linting utility

* ci: add commit-lint to ci

* refactor: better messaging on failed linting

* wip: commit grabbing

* ci: fetch depth when linting commits

* ci: fetch depth when linting commits

* ci: checkout?

* ci: checkout?

* ci: checkout?

* fix: amend regexp

* fix: pattern matching in commit lint

* fix: pattern matching in commit lint

* docs: document lint-commit script

.github/workflows/nodejs.yml

@@ -13,6 +13,16 @@ jobs:
     - uses: actions/checkout@v3
     - run: . ./script/check-deps
 
+  commit-lint:
+    name: Commit message hygiene
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+      with:
+        fetch-depth: 0
+    - run: git fetch
+    - run: . ./script/lint-commits
+
   dependencies:
     runs-on: ubuntu-latest
 

script/lint-commits

@@ -0,0 +1,38 @@
+#!/usr/bin/bash
+
+#
+# This loosely implements the commit message linting check described by
+# Conventional Commit (https://www.conventionalcommits.org). Commits merged in
+# branches on this repository are expected to meet that general format:
+#
+# <prefix>: <message>
+#
+# where <prefix> is one of the prefixes included in the filters below.
+#
+
+CURRENT_HEAD=$(git rev-parse HEAD)
+BASE_HEAD=$(git log origin/main..$CURRENT_HEAD --oneline --format=%H | tail -1)
+COMMITS=$(git log $BASE_HEAD..$CURRENT_HEAD --oneline --format=%s)
+
+if [[ -z "$COMMITS" ]]; then
+    echo "No commits."
+    exit 0
+fi
+
+INVALID_COMMITS_FOUND=0
+
+while IFS='\n' read -r line; do
+    if [[ $line =~ ^"Merge "[0-9a-z]+" into "[0-9a-z]+$ ]]; then
+        continue
+    elif [[ ($line =~ ^(feat|chore|fix|refactor|wip|docs|build|ci|perf):) ]]; then
+        echo "VALID - $line"
+    else
+        echo "INVALID - $line"
+        INVALID_COMMITS_FOUND=$((INVALID_COMMITS_FOUND+1))
+    fi;
+done <<< "$COMMITS"
+
+if [[ $INVALID_COMMITS_FOUND -gt 0 ]]; then
+    echo "$INVALID_COMMITS_FOUND bad commit messages found."
+    exit 1
+fi