feat(testing): add serviceWorker tests

test/serviceWorker.test.ts

@@ -1,9 +1,44 @@
+import makeServiceWorkerEnv = require("service-worker-mock")
+const makeFetchMock = require("service-worker-mock/fetch")
+
 describe("serviceWorker", () => {
-  it("should add the proper eventListeners", () => {
-    // make sure install, active and fetch were added as event listeners
+  let spy: jest.SpyInstance
+  beforeEach(() => {
+    Object.assign(
+      global,
+      makeServiceWorkerEnv(),
+      makeFetchMock(),
+      // If you're using sinon ur similar you'd probably use below instead of makeFetchMock
+      // fetch: sinon.stub().returns(Promise.resolve())
+    )
+    jest.resetModules()
+
+    spy = jest.spyOn(console, "log")
   })
 
-  it("should call the proper callbacks", () => {
-    // somehow test Line 8 with the events waitUntil..
+  afterEach(() => {
+    jest.restoreAllMocks()
+    spy.mockRestore()
   })
-})
+
+  it("should add listeners", () => {
+    require("../src/browser/serviceWorker.ts")
+    const _self = (self as unknown) as WorkerGlobalScope
+    expect(_self.listeners.get("install")).toBeDefined()
+    expect(_self.listeners.get("activate")).toBeDefined()
+    expect(_self.listeners.get("fetch")).toBeDefined()
+  })
+
+  it("should call the proper callbacks for 'install'", async () => {
+    require("../src/browser/serviceWorker.ts")
+    await self.trigger("install")
+    expect(spy).toHaveBeenCalledWith("[Service Worker] installed")
+  })
+  it("should call the proper callbacks for 'activate'", async () => {
+    require("../src/browser/serviceWorker.ts")
+    await self.trigger("activate")
+
+    // Activate serviceWorker
+    expect(spy).toHaveBeenCalledWith("[Service Worker] activated")
+  })
+})