test coverage

src/Network.js

@@ -52,7 +52,7 @@ export default function Network({ network }) {
     return () => {
       clearInterval(timer)
     }
-  }, [network.url])
+  }, [network])
 
   const isOnline = status === 'Online'
 

src/Network.test.js

@@ -1,5 +1,5 @@
 import React from 'react'
-import { render, waitForElement } from '@testing-library/react'
+import { render, wait } from '@testing-library/react'
 import mockAxios from 'axios'
 import Network from './Network'
 
@@ -11,6 +11,7 @@ const mockResponse = {
 
 afterEach(() => {
   mockAxios.reset()
+  jest.clearAllTimers()
 })
 
 describe('Network', () => {
@@ -24,11 +25,26 @@ describe('Network', () => {
   }
 
   it('renders without crashing', async () => {
-    mockAxios.post.mockResolvedValueOnce(mockResponse)
-
-    const { container, getByTitle } = render(<Network network={network} />)
+    mockAxios.post.mockResolvedValue(mockResponse)
+    const { container } = render(<Network network={network} />)
     expect(container.firstChild).toBeInTheDocument()
-    await waitForElement(() => getByTitle('Current block number'))
+    await wait()
     expect(mockAxios.post).toHaveBeenCalledTimes(2)
   })
+
+  it('renders without response', async () => {
+    mockAxios.post.mockResolvedValue(undefined)
+    const { container } = render(<Network network={network} />)
+    await wait()
+    expect(container.firstChild).toBeInTheDocument()
+  })
+
+  it('re-fetches after 5 sec.', async () => {
+    jest.useFakeTimers()
+    mockAxios.post.mockResolvedValue(mockResponse)
+    render(<Network network={network} />)
+    jest.advanceTimersByTime(6000)
+    await wait()
+    expect(setInterval).toHaveBeenCalledTimes(1)
+  })
 })

src/index.test.js

@@ -1,12 +1,22 @@
-import { act } from '@testing-library/react'
+import ReactDOM from 'react-dom'
 import { renderToDOM } from '.'
 
-describe('index', () => {
-  it('should be able to run tests', () => {
-    expect(1 + 2).toEqual(3)
+describe('test ReactDOM.render', () => {
+  const originalRender = ReactDOM.render
+  const originalGetElement = global.document.getElementById
+
+  beforeEach(() => {
+    global.document.getElementById = () => true
+    ReactDOM.render = jest.fn()
   })
 
-  it('renders without crashing', () => {
-    act(() => renderToDOM())
+  afterAll(() => {
+    global.document.getElementById = originalGetElement
+    ReactDOM.render = originalRender
+  })
+
+  it('should call ReactDOM.render', () => {
+    renderToDOM()
+    expect(ReactDOM.render).toHaveBeenCalled()
   })
 })

src/rpc.js

@@ -1,5 +1,22 @@
 import axios from 'axios'
 
+async function axiosRpcRequest(url, method) {
+  try {
+    const response = await axios.post(url, {
+      method,
+      params: [],
+      id: 1,
+      jsonrpc: '2.0'
+    })
+
+    return response
+  } catch (error) {
+    return error
+  }
+}
+
+export { axiosRpcRequest }
+
 // Measure response time and deliver as `response.duration`
 axios.interceptors.request.use(
   config => {
@@ -23,20 +40,3 @@ axios.interceptors.response.use(
     return Promise.reject(error)
   }
 )
-
-async function axiosRpcRequest(url, method) {
-  try {
-    const response = await axios.post(url, {
-      method,
-      params: [],
-      id: 1,
-      jsonrpc: '2.0'
-    })
-
-    return response
-  } catch (error) {
-    return error
-  }
-}
-
-export { axiosRpcRequest }