Add type definitions for service-worker-mock (#36791)

* Add type definitions for service-worker-mock

* Fix linting issues

* Process feedback

types/service-worker-mock/index.d.ts

@@ -0,0 +1,56 @@
+// Type definitions for service-worker-mock 2.0
+// Project: https://github.com/pinterest/service-workers/tree/master/packages/service-worker-mock#readme
+// Definitions by: Remco Haszing <https://github.com/remcohaszing>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 2.8
+
+export = makeServiceWorkerEnv;
+declare function makeServiceWorkerEnv(): WorkerGlobalScope;
+
+declare namespace makeServiceWorkerEnv {
+    interface Caches {
+        [key: string]: Cache;
+    }
+
+    type Listeners = Map<keyof ServiceWorkerGlobalScopeEventMap, EventListener>;
+
+    interface Snapshot {
+        /**
+         * A key/value map of current cache contents.
+         */
+        caches: Caches;
+
+        /**
+         * A list of active clients.
+         */
+        clients: Client[];
+
+        /**
+         * A list of active notifications.
+         */
+        notifications: Notification[];
+    }
+}
+
+declare global {
+    /**
+     * A key/value map of active listeners (`install`/`activate`/`fetch`/etc).
+     */
+    const listeners: makeServiceWorkerEnv.Listeners;
+
+    /**
+     * Used to trigger active listeners.
+     */
+    function trigger(type: keyof ServiceWorkerGlobalScopeEventMap): Promise<void>;
+
+    /**
+     * Used to generate a snapshot of the service worker internals.
+     */
+    function snapshot(): makeServiceWorkerEnv.Snapshot;
+
+    interface WorkerGlobalScope {
+        listeners: typeof listeners;
+        trigger: typeof trigger;
+        snapshot: typeof snapshot;
+    }
+}

types/service-worker-mock/service-worker-mock-tests.ts

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+import makeServiceWorkerEnv = require('service-worker-mock');
+
+const mock = makeServiceWorkerEnv();
+
+Object.assign(self, mock);
+
+trigger('install');
+mock.trigger('install');
+trigger('fetch');
+mock.trigger('fetch');
+
+const emitFetch = listeners.get('fetch') as EventListener;
+emitFetch(new Event('fetch'));
+
+mock.caches.open('OLD_CACHE');
+console.log(snapshot().caches.OLD_CACHE);
+console.log(self.snapshot().clients[0].id);
+console.log(mock.snapshot().notifications[0].body);

types/service-worker-mock/tsconfig.json

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+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": [
+            "es6",
+            "webworker"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictFunctionTypes": true,
+        "strictNullChecks": true,
+        "baseUrl": "../",
+        "typeRoots": [
+            "../"
+        ],
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true
+    },
+    "files": [
+        "index.d.ts",
+        "service-worker-mock-tests.ts"
+    ]
+}

types/service-worker-mock/tslint.json

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+{ "extends": "dtslint/dt.json" }