fix: fall back to conventional commit-parser settings for missing keys

BREAKING CHANGE
This potentially changes implicit commitlint behaviour users may
have relied on in earlier versions. Instead of falling back to the
builtin commit-parser defaults we now default all keys to
conventional-changelog-angular.

@commitlint/parse/package.json

@@ -73,6 +73,7 @@
   },
   "dependencies": {
     "conventional-changelog-angular": "^1.3.3",
-    "conventional-commits-parser": "^2.1.0"
+    "conventional-commits-parser": "^2.1.0",
+    "lodash": "^4.17.11"
   }
 }

@commitlint/parse/src/index.js

@@ -1,15 +1,12 @@
 import {sync} from 'conventional-commits-parser';
 import defaultChangelogOpts from 'conventional-changelog-angular';
+import {merge} from 'lodash';
 
 export default parse;
 
 async function parse(message, parser = sync, parserOpts) {
-	if (!parserOpts || Object.keys(parserOpts || {}).length === 0) {
-		const changelogOpts = await defaultChangelogOpts;
-		parserOpts = changelogOpts.parserOpts;
-	}
-
-	const parsed = parser(message, parserOpts);
+	const defaultOpts = (await defaultChangelogOpts).parserOpts;
+	const parsed = parser(message, merge({}, defaultOpts, parserOpts));
 	parsed.raw = message;
 	return parsed;
 }

@commitlint/parse/src/index.test.js

@@ -164,3 +164,28 @@ test('parses custom references', async t => {
 		repository: null
 	});
 });
+
+test('uses permissive default regex without parser opts', async t => {
+	const message = 'chore(component,demo): bump';
+	const actual = await parse(message);
+
+	t.is(actual.scope, 'component,demo');
+});
+
+test('uses permissive default regex with other parser opts', async t => {
+	const message = 'chore(component,demo): bump';
+	const actual = await parse(message, undefined, {commentChar: '#'});
+
+	t.is(actual.scope, 'component,demo');
+});
+
+test('uses restrictive default regex in passed parser opts', async t => {
+	const message = 'chore(component,demo): bump';
+	const actual = await parse(message, undefined, {
+		headerPattern: /^(\w*)(?:\(([a-z]*)\))?: (.*)$/
+	});
+
+	t.is(actual.subject, null);
+	t.is(actual.message, undefined);
+	t.is(actual.scope, null);
+});