Update type-empty rule

@commitlint/rules/src/type-empty.test.ts

@@ -4,11 +4,17 @@ import {typeEmpty} from './type-empty';
 const messages = {
 	empty: '(scope):',
 	filled: 'type: subject',
+	fullyFilled: 'type(scope): subject',
+	subjectOnly: 'subject',
+	separator: ': subject',
 };
 
 const parsed = {
 	empty: parse(messages.empty),
 	filled: parse(messages.filled),
+	fullyFilled: parse(messages.fullyFilled),
+	subjectOnly: parse(messages.subjectOnly),
+	separator: parse(messages.separator),
 };
 
 test('without type should succeed for empty keyword', async () => {
@@ -46,3 +52,57 @@ test('with type fail for "always"', async () => {
 	const expected = false;
 	expect(actual).toEqual(expected);
 });
+
+test('with title, scope and subject should fail for empty keyword', async () => {
+	const [actual] = typeEmpty(await parsed.fullyFilled);
+	const expected = false;
+	expect(actual).toEqual(expected);
+});
+
+test('with  title, scope and subject should succeed for "never"', async () => {
+	const [actual] = typeEmpty(await parsed.fullyFilled, 'never');
+	const expected = true;
+	expect(actual).toEqual(expected);
+});
+
+test('with  title, scope and subject should fail for "always"', async () => {
+	const [actual] = typeEmpty(await parsed.fullyFilled, 'always');
+	const expected = false;
+	expect(actual).toEqual(expected);
+});
+
+test('with only subject should succeed for empty keyword', async () => {
+	const [actual] = typeEmpty(await parsed.subjectOnly);
+	const expected = true;
+	expect(actual).toEqual(expected);
+});
+
+test('with only subject should fail for "never"', async () => {
+	const [actual] = typeEmpty(await parsed.subjectOnly, 'never');
+	const expected = false;
+	expect(actual).toEqual(expected);
+});
+
+test('with only subject should succeed for "always"', async () => {
+	const [actual] = typeEmpty(await parsed.subjectOnly, 'always');
+	const expected = true;
+	expect(actual).toEqual(expected);
+});
+
+test('without type but with a separator should fail for empty keyword', async () => {
+	const [actual] = typeEmpty(await parsed.separator);
+	const expected = false;
+	expect(actual).toEqual(expected);
+});
+
+test('without type but with a separator should succeed for "never"', async () => {
+	const [actual] = typeEmpty(await parsed.separator, 'never');
+	const expected = true;
+	expect(actual).toEqual(expected);
+});
+
+test('without type but with a separator should fail for "always"', async () => {
+	const [actual] = typeEmpty(await parsed.separator, 'always');
+	const expected = false;
+	expect(actual).toEqual(expected);
+});

@commitlint/rules/src/type-empty.ts

@@ -4,7 +4,14 @@ import {SyncRule} from '@commitlint/types';
 
 export const typeEmpty: SyncRule = (parsed, when = 'always') => {
 	const negated = when === 'never';
-	const notEmpty = ensure.notEmpty(parsed.type || '');
+	const notEmptyType = ensure.notEmpty(parsed.type || '');
+	let notEmpty = notEmptyType;
+	if (
+		!notEmptyType &&
+		parsed.subject !== parsed.header &&
+		parsed.header.substring(0, 1) === ':'
+	)
+		notEmpty = true;
 	return [
 		negated ? notEmpty : !notEmpty,
 		message(['type', negated ? 'may not' : 'must', 'be empty']),