fix(load): use Rule | AsyncRule | SyncRule as rule value type in Plugin (#2146)

Use `Rule | AsyncRule | SyncRule` instead of `Rule<unknown>` so plugin developers don't need to
cast every non-default rule's value to `Rule<unknown>`, but can define and assign their rules as
`Rule | AsyncRule | SyncRule` instead.

Author: jdbruijn

@commitlint/load/src/utils/load-plugin.test.ts

@@ -1,4 +1,5 @@
 import loadPlugin from './load-plugin';
+import {AsyncRule, Plugin, Rule, SyncRule} from '@commitlint/types';
 
 jest.mock('commitlint-plugin-example', () => ({example: true}), {
 	virtual: true,
@@ -8,6 +9,39 @@ jest.mock('@scope/commitlint-plugin-example', () => ({scope: true}), {
 	virtual: true,
 });
 
+jest.mock(
+	'commitlint-plugin-rule',
+	(): Plugin => {
+		const rule: Rule<number> = (_parsed, when, _value) => {
+			return [when === 'never'];
+		};
+		return {rules: {rule}};
+	},
+	{virtual: true}
+);
+
+jest.mock(
+	'commitlint-plugin-sync-rule',
+	(): Plugin => {
+		const syncRule: SyncRule<number> = (_parsed, when, _value) => {
+			return [when === 'never'];
+		};
+		return {rules: {syncRule}};
+	},
+	{virtual: true}
+);
+
+jest.mock(
+	'commitlint-plugin-async-rule',
+	(): Plugin => {
+		const asyncRule: AsyncRule<number> = (_parsed, when, _value) => {
+			return new Promise(() => [when === 'never']);
+		};
+		return {rules: {asyncRule}};
+	},
+	{virtual: true}
+);
+
 test('should load a plugin when referenced by short name', () => {
 	const plugins = loadPlugin({}, 'example');
 	expect(plugins['example']).toBe(require('commitlint-plugin-example'));
@@ -18,6 +52,21 @@ test('should load a plugin when referenced by long name', () => {
 	expect(plugins['example']).toBe(require('commitlint-plugin-example'));
 });
 
+test('should load a plugin with a rule', () => {
+	const plugins = loadPlugin({}, 'commitlint-plugin-rule');
+	expect(plugins['rule']).toBe(require('commitlint-plugin-rule'));
+});
+
+test('should load a plugin with a sync rule', () => {
+	const plugins = loadPlugin({}, 'commitlint-plugin-sync-rule');
+	expect(plugins['sync-rule']).toBe(require('commitlint-plugin-sync-rule'));
+});
+
+test('should load a plugin with an async rule', () => {
+	const plugins = loadPlugin({}, 'commitlint-plugin-async-rule');
+	expect(plugins['async-rule']).toBe(require('commitlint-plugin-async-rule'));
+});
+
 test('should throw an error when a plugin has whitespace', () => {
 	expect(() => loadPlugin({}, 'whitespace ')).toThrow(
 		"Whitespace found in plugin name 'whitespace '"

@commitlint/types/src/load.ts

@@ -1,10 +1,16 @@
-import {Rule, RulesConfig, RuleConfigQuality} from './rules';
+import {
+	Rule,
+	RulesConfig,
+	RuleConfigQuality,
+	AsyncRule,
+	SyncRule,
+} from './rules';
 
 export type PluginRecords = Record<string, Plugin>;
 
 export interface Plugin {
 	rules: {
-		[ruleName: string]: Rule<unknown>;
+		[ruleName: string]: Rule | AsyncRule | SyncRule;
 	};
 }