Add plugin implemenation type (#2355)

* types: add plugin implementation type for plugin authors

* build: properly lint ts sources and tests

* uncomment tests

package.json

@@ -117,10 +117,15 @@
     "README.md"
   ],
   "lint-staged": {
-    "*.ts": [
+    "{src,bin,browser,typings}/**/*.ts": [
       "tslint --project . --fix",
       "prettier --write",
       "git add"
+    ],
+    "test/**/*.ts": [
+      "tslint --project test/typescript --fix",
+      "prettier --write",
+      "git add"
     ]
   }
 }

src/rollup/types.d.ts

@@ -148,6 +148,18 @@ export type ResolveDynamicImportHook = (
 
 export type AddonHook = string | ((this: PluginContext) => string | Promise<string>);
 
+/**
+ * use this type for plugin annotation
+ * @example
+ * ```ts
+ * interface Options {
+ * ...
+ * }
+ * const myPlugin: PluginImpl<Options> = (options = {}) => { ... }
+ * ```
+ */
+export type PluginImpl<O extends object = object> = (options?: O) => Plugin;
+
 export interface Plugin {
 	name: string;
 	options?: (options: InputOptions) => InputOptions | void | null;

test/typescript/index.ts

@@ -1 +1,14 @@
 import * as rollup from './dist/rollup';
+
+// Plugin API
+interface Options {
+	extensions?: string | string[];
+}
+const plugin: rollup.PluginImpl<Options> = (options = {}) => {
+	// tslint:disable-next-line:no-unused-variable
+	const extensions = options.extensions || ['.js'];
+	return { name: 'my-plugin' };
+};
+
+plugin();
+plugin({ extensions: ['.js', 'json'] });