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Testing Cheatsheet

11 playbook/playbook

Jest

jest.spyOn(dbClient, 'getData').mockImplementation(()=>data)

Mocking 3rd party apis:​

  1. Mock the whole library: jest.mock('@aws-sdk/client-comprehend-node/ComprehendClient') - This mocks the whole library, for example on your code: const comprehend = new ComprehendClient({region: "ap-southeast-2"});

  2. Still import your actual library in your test: const {ComprehendClient} = require("@aws-sdk/client-comprehend-node/ComprehendClient");

  3. On your test automatic mocks are accessible (both instance and method):

expect(ComprehendClient).toHaveBeenCalledTimes(1);
const instance = ComprehendClient.mock.instances[0];
expect(instance.send).toHaveBeenCalledTimes(1)

Mocking specific​

  • Repeat steps 1, 2 from above then on each test:
ComprehendClient.mockImplementation(() => {
    return {
        send: () => actualResponse
 }
});

Simple Screen React​

import {render, screen} from '@testing-library/react'
import {SimpleForm} from "./simpleForm";

describe('simpleForm', function () {
    it('should run', function () {

    });
 it('should have text field and submit button', function () {
        render(<SimpleForm/>)
        const field = screen.getByText('enter field')
        expect(field).toBeTruthy()
    });
});

Changing the state front end​

render(<SimpleForm/>);
await act(async () => {
    userEvent.type(screen.getByRole('textbox'), 'Hello World!')
    userEvent.click(screen.getByRole('button'))
})
expect(screen.getByText('queued')).toBeInTheDocument();

Mocking Fetch API​

Automatic Fetch Mocks:

  1. Import
import fetchMock from "jest-fetch-mock"

  1. Global:
fetchMock.enableMocks()
  1. Before Each
fetchMock.doMock();
  1. Finally Mock:
fetch.mockResponse(JSON.stringify(sampleResponse))

AWS Notes:

Checking if AWS credentials has been setup:

const getAWSCredentials = () => {
    AWS.config.getCredentials(function (err) {
        if (err) console.log(err.stack);
 else {
            console.log("Access key:", AWS.config.credentials.accessKeyId);
 }
    });
}

Node end to end notes:

npx express-generator
res.header("Access-Control-Allow-Origin", "*");
res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");

npm install cors()

const app = express();
app.use(cors())

API Gateway

  • API Key Request needs the following headers:
const headers = {
   crossDomain: true,
method: 'GET',
headers: {
       'Content-Type': 'application/json',
'X-API-Key': ''
}
}
  • Publish API to stage to enable access to URL

HTTP input stream (Backend)

whenever(request.inputStream).thenReturn(DelegatingServletInputStream(ByteArrayInputStream(validPayload.toByteArray())))
String json = "{\"id\":213213213, \"amount\":222}";
when(request.getInputStream()).thenReturn(
    new DelegatingServletInputStream(
        new ByteArrayInputStream(json.getBytes(StandardCharsets.UTF_8))));
when(request.getReader()).thenReturn(
    new BufferedReader(new StringReader(json)));
when(request.getContentType()).thenReturn("application/json");
when(request.getCharacterEncoding()).thenReturn("UTF-8");
```