👩‍💻 dx: Set up commitlint.

Fixes #805.

.husky/commit-msg

@@ -0,0 +1,52 @@
+#!/bin/sh
+. "$(dirname "$0")/_/husky.sh"
+
+function ask () {
+
+	# This is a general-purpose function to ask Yes/No questions in Bash, either
+	# with or without a default answer. It keeps repeating the question until it
+	# gets a valid answer.
+
+	# http://djm.me/ask
+
+	if [ "${2:-}" = "Y" ]; then
+		prompt="Y/n"
+		default=Y
+	elif [ "${2:-}" = "N" ]; then
+		prompt="y/N"
+		default=N
+	else
+		prompt="y/n"
+		default=
+	fi
+
+	while true; do
+
+		# Ask the question (not using "read -p" as it uses stderr not stdout)
+		echo -n "$1 [$prompt] "
+
+		# Read the answer (use /dev/tty in case stdin is redirected from somewhere else)
+		read REPLY </dev/tty
+
+		# Default?
+		if [ -z "$REPLY" ]; then
+			REPLY=$default
+		fi
+
+		# Check if the reply is valid
+		case "$REPLY" in
+			Y*|y*) return 0 ;;
+			N*|n*) return 1 ;;
+		esac
+
+	done
+
+}
+
+while ! npm run commit-msg -- "$1" ; do
+	if [ -t 1 ] && ask 'There was an error. Do you wish to amend your commit message?' Y ; then
+		${GIT_EDITOR:-$EDITOR} "$1" < /dev/tty
+	else
+		exit 1
+	fi
+done

commitlint.config.ts

@@ -0,0 +1,76 @@
+/**
+ * Commit Lint
+ *
+ * Rules are made up by a name and a configuration array.
+ * The configuration array contains:
+ * 1. Level:      | [0..2] | 0 = disables | 1 = considered a warning | 2 an error for the rule.
+ * 2. Applicable: | always/never | never inverts the rule.
+ * 3. Value:      | value to use for this rule.
+ *
+ * @link https://github.com/conventional-changelog/commitlint/blob/master/docs/reference/rules-configuration.md
+ */
+
+export default {
+	parserPreset: {
+		parserOpts: {
+			headerPattern: /^:[a-z\d_]+: (\w+)(?:\((.+)\))?!?: (.+)$/,
+			breakingHeaderPattern: /^:boom: (\w+)(?:\((.+)\))?!: (.+)$/,
+			headerCorrespondence: ['type', 'scope', 'subject'],
+			noteKeywords: ['BREAKING CHANGE'],
+			revertPattern:
+				/^:wastebasket: revert:\s"?([\s\S]+?)"?\s*this reverts commit (\w+)\./i,
+			revertCorrespondence: ['header', 'hash'],
+			issuePrefixes: ['#'],
+		},
+	},
+	rules: {
+		'header-max-length': [2, 'always', 79],
+		'body-max-line-length': [2, 'always', 79],
+		'footer-max-line-length': [2, 'always', 79],
+		'type-empty': [2, 'never'],
+		'type-case': [2, 'always', 'lower-case'],
+		'type-enum': [
+			2,
+			'always',
+			[
+				'a11y',
+				'bug',
+				'chore',
+				'cleaning',
+				'config',
+				'deprecate',
+				'deps',
+				'docs',
+				'dx',
+				'experiment',
+				'feat',
+				'fix',
+				'i18n',
+				'idea',
+				'initial',
+				'license',
+				'merge',
+				'perf',
+				'progress',
+				'refactor',
+				'release',
+				'revert',
+				'security',
+				'style',
+				'test',
+				'trash',
+				'typo',
+				'ui',
+				'ux',
+			],
+		],
+		'scope-case': [0, 'always', 'lower-case'],
+		'subject-empty': [2, 'never'],
+		'subject-case': [2, 'always', 'sentence-case'],
+		'subject-full-stop': [2, 'always', '.'],
+		'body-leading-blank': [2, 'always'],
+		'body-empty': [0, 'never'],
+		'body-full-stop': [2, 'always', '.'],
+		'footer-leading-blank': [2, 'always'],
+	},
+};