Update examples in README

CHANGELOG.md

@@ -15,6 +15,11 @@ project adheres to
 ### Improved
 
 - Move from jest.Mock to jest.MockedFunction
+- Update README.md
+
+### Added
+
+* Add lastError example to demo test and README.md
 
 ## [**0.3.0**] - 2020-02-13
 

README.md

@@ -6,10 +6,13 @@ A complete mock of the Chrome API for Chrome extensions, for use
 with Jest.
 
 The `chrome` object is based on schemas from the Chromium
-project.
+project, with thanks to
+[`sinon-chrome`](https://github.com/acvetkov/sinon-chrome) for
+compiling the schemas.
 
 TypeScript support is built in. Each function and event is typed
-using the types from [`@types/chrome`](https://www.npmjs.com/package/@types/chrome).
+using the types from
+[`@types/chrome`](https://www.npmjs.com/package/@types/chrome).
 
 ## Usage
 
@@ -29,6 +32,69 @@ test('chrome api functions', () => {
   expect(chrome.runtime.getManifest).toBeCalled()
 })
 
+test('chrome api functions with callback', () => {
+  const message = { greeting: 'hello?' }
+  const response = { greeting: 'here I am' }
+  const callbackSpy = jest.fn()
+
+  chrome.runtime.sendMessage.mockImplementation(
+    (message, callback) => {
+      callback(response)
+    },
+  )
+
+  chrome.runtime.sendMessage(message, callbackSpy)
+
+  expect(chrome.runtime.sendMessage).toBeCalledWith(
+    message,
+    callbackSpy,
+  )
+  expect(callbackSpy).toBeCalledWith(response)
+})
+
+test('chrome api functions with lastError', () => {
+  const message = { greeting: 'hello?' }
+  const response = { greeting: 'here I am' }
+
+  const lastErrorSpy = jest.fn()
+  const callbackSpy = jest.fn(() => {
+    if (chrome.runtime.lastError) {
+      lastErrorSpy(chrome.runtime.lastError.message)
+    }
+  })
+
+  const lastErrorMessage = 'this is an error'
+  const lastErrorGetter = jest.fn(() => lastErrorMessage)
+  const lastError = {
+    get message() {
+      return lastErrorGetter()
+    },
+  }
+
+  chrome.runtime.sendMessage.mockImplementation(
+    (message, callback) => {
+      chrome.runtime.lastError = lastError
+
+      callback(response)
+
+      delete chrome.runtime.lastError
+    },
+  )
+
+  chrome.runtime.sendMessage(message, callbackSpy)
+
+  expect(chrome.runtime.sendMessage).toBeCalledWith(
+    message,
+    callbackSpy,
+  )
+
+  expect(callbackSpy).toBeCalledWith(response)
+  expect(lastErrorGetter).toBeCalled()
+  expect(lastErrorSpy).toBeCalledWith(lastErrorMessage)
+
+  expect(chrome.runtime.lastError).toBeUndefined()
+})
+
 test('chrome api events', () => {
   const listenerSpy = jest.fn()
   const sendResponseSpy = jest.fn()

src/demo.test.ts

@@ -13,6 +13,69 @@ test('chrome api functions', () => {
   expect(chrome.runtime.getManifest).toBeCalled()
 })
 
+test('chrome api functions with callback', () => {
+  const message = { greeting: 'hello?' }
+  const response = { greeting: 'here I am' }
+  const callbackSpy = jest.fn()
+
+  chrome.runtime.sendMessage.mockImplementation(
+    (message, callback) => {
+      callback(response)
+    },
+  )
+
+  chrome.runtime.sendMessage(message, callbackSpy)
+
+  expect(chrome.runtime.sendMessage).toBeCalledWith(
+    message,
+    callbackSpy,
+  )
+  expect(callbackSpy).toBeCalledWith(response)
+})
+
+test('chrome api functions with lastError', () => {
+  const message = { greeting: 'hello?' }
+  const response = { greeting: 'here I am' }
+
+  const lastErrorSpy = jest.fn()
+  const callbackSpy = jest.fn(() => {
+    if (chrome.runtime.lastError) {
+      lastErrorSpy(chrome.runtime.lastError.message)
+    }
+  })
+
+  const lastErrorMessage = 'this is an error'
+  const lastErrorGetter = jest.fn(() => lastErrorMessage)
+  const lastError = {
+    get message() {
+      return lastErrorGetter()
+    },
+  }
+
+  chrome.runtime.sendMessage.mockImplementation(
+    (message, callback) => {
+      chrome.runtime.lastError = lastError
+
+      callback(response)
+
+      delete chrome.runtime.lastError
+    },
+  )
+
+  chrome.runtime.sendMessage(message, callbackSpy)
+
+  expect(chrome.runtime.sendMessage).toBeCalledWith(
+    message,
+    callbackSpy,
+  )
+
+  expect(callbackSpy).toBeCalledWith(response)
+  expect(lastErrorGetter).toBeCalled()
+  expect(lastErrorSpy).toBeCalledWith(lastErrorMessage)
+
+  expect(chrome.runtime.lastError).toBeUndefined()
+})
+
 test('chrome api events', () => {
   const listenerSpy = jest.fn()
   const sendResponseSpy = jest.fn()