diff --git a/test/register.test.ts b/test/register.test.ts
index 8f84b7eb..421e1d4f 100644
--- a/test/register.test.ts
+++ b/test/register.test.ts
@@ -2,7 +2,8 @@ import { JSDOM } from "jsdom"
 // Note: we need to import logger from the root
 // because this is the logger used in logError in ../src/common/util
 import { logger } from "../node_modules/@coder/logger"
-import { registerServiceWorker } from "../src/browser/register"
+import { registerServiceWorker, handleServiceWorkerRegistration } from "../src/browser/register"
+import { Options } from "../src/common/util"
 const { window } = new JSDOM()
 global.window = (window as unknown) as Window & typeof globalThis
 global.document = window.document
@@ -10,7 +11,10 @@ global.navigator = window.navigator
 
 describe("register", () => {
   describe("registerServiceWorker", () => {
-    const spy = jest.fn()
+    let spy: jest.MockedFunction<(
+      scriptURL: string,
+      options?: RegistrationOptions | undefined,
+    ) => Promise<ServiceWorkerRegistration>>
     let loggerSpy: jest.SpyInstance
 
     beforeAll(() => {
@@ -25,6 +29,8 @@ describe("register", () => {
 
     beforeEach(() => {
       loggerSpy = jest.spyOn(logger, "error")
+      spy = jest.fn()
+      global.navigator.serviceWorker.register = spy
     })
 
     afterEach(() => {
@@ -37,7 +43,6 @@ describe("register", () => {
 
     it("should register a ServiceWorker", () => {
       global.navigator.serviceWorker.register = spy
-      // call registerServiceWorker
       const path = "/hello"
       const mockOptions = {
         base: "",
@@ -50,7 +55,7 @@ describe("register", () => {
       expect(spy).toHaveBeenCalledTimes(1)
     })
 
-    it("should log an error if something goes work", () => {
+    it("should log an error if something doesn't work", () => {
       const message = "Can't find browser"
       const path = "/hello"
       const mockOptions = {
@@ -67,5 +72,63 @@ describe("register", () => {
       expect(loggerSpy).toHaveBeenCalledTimes(1)
       expect(loggerSpy).toHaveBeenCalledWith(`[Service Worker] failed to register: ${message}`)
     })
+
+    it("should work when base is undefined", () => {
+      const path = "/hello"
+
+      // We want to test some code that checks if options.base is undefined
+      // so we leave it off mockOptions
+      // but assert it as Options so TS is happy
+      const mockOptions = {
+        csStaticBase: "",
+        logLevel: 0,
+      } as Options
+      registerServiceWorker(navigator, path, mockOptions)
+      // expect spy to have been called
+      expect(spy).toHaveBeenCalled()
+      expect(spy).toHaveBeenCalledTimes(1)
+    })
+  })
+
+  describe("handleServiceWorkerRegistration", () => {
+    let getOptionsMock: jest.MockedFunction<() => {
+      base: string
+      csStaticBase: string
+      logLevel: number
+    }>
+    let normalizeMock: jest.MockedFunction<(v: string) => string>
+    let registerServiceWorkerMock: jest.MockedFunction<(
+      navigator: Navigator,
+      path: string,
+      mockOptions: Options,
+    ) => Promise<void>>
+
+    beforeEach(() => {
+      getOptionsMock = jest.fn(() => ({
+        base: "",
+        csStaticBase: "",
+        logLevel: 0,
+      }))
+
+      normalizeMock = jest.fn((url: string) => "qux///")
+
+      registerServiceWorkerMock = jest
+        .fn()
+        .mockImplementation((navigator: Navigator, path: string, mockOptions: Options) => Promise.resolve())
+    })
+    it("should work when called", () => {
+      handleServiceWorkerRegistration({
+        getOptions: getOptionsMock,
+        normalize: normalizeMock,
+        registerServiceWorker: registerServiceWorkerMock,
+      })
+
+      const mocks = [getOptionsMock, normalizeMock, registerServiceWorkerMock]
+
+      mocks.forEach((mock) => {
+        expect(mock).toHaveBeenCalled()
+        expect(mock).toHaveBeenCalledTimes(1)
+      })
+    })
   })
 })