I have function below. I can't test this function using Jest framework.
The function:
const XMLHttpRequest = require('xmlhttprequest').XMLHttpRequest;
exports.xhrExample = function() {
var xhr = new XMLHttpRequest();
xhr.open('POST', 'url' , true);
xhr.setRequestHeader('Content-Type', 'application/json');
xhr.onreadystatechange = function () {
if (xhr.readyState === 4 && xhr.status === 200) {
var response = JSON.parse(xhr.responseText);
console.log('Some text');
console.log('Some text');
}
};
xhr.send(/*body*/);
}
The test:
/**
* @jest-environment jsdom
*/
const { xhrExample } = require('../function/exampleXHR');
const open = jest.fn();
const setRequestHeader = jest.fn();
const send = jest.fn();
const status = 200;
const readyState = 4;
const xhrMockClass = function () {
return {
open,
setRequestHeader,
send,
status,
readyState
};
};
global.XMLHttpRequest = jest.fn().mockImplementation(xhrMockClass);
test('Should make a request', () => {
xhrExample();
})
In particular I can't cover if branch. How can I write the right test? I've seen many solutions but they don't work. I also used the xhr-mock utility but it still not working. Thanks to all.
I will create an HTTP server to test it instead of mocking. Your code doesn't make sense, I did some refactoring and added opts parameters for xhrExample function. It's more generic and easier to test.
E.g.
exampleXHR.js:
const XMLHttpRequest = require('xmlhttprequest').XMLHttpRequest;
exports.xhrExample = function (opts) {
var xhr = new XMLHttpRequest();
xhr.open(opts.method, opts.url, true);
xhr.setRequestHeader('Content-Type', 'application/json');
xhr.onreadystatechange = function () {
if (xhr.readyState === 4 && xhr.status === 200) {
var response = JSON.parse(xhr.responseText);
opts.onSuccess(response);
}
};
xhr.send();
};
exampleXHR.test.js:
const http = require('http');
const { xhrExample } = require('./exampleXHR');
describe('71021143', () => {
let server;
beforeEach((done) => {
server = http
.createServer((req, res) => {
const body = JSON.stringify({ name: 'amelia' });
res.writeHead(200, {
'Content-Type': 'application/json',
'Content-Length': Buffer.byteLength(body),
});
res.write(body);
res.end();
})
.listen(8000, done);
});
afterEach((done) => {
server.close(done);
});
test('should pass', (done) => {
expect.assertions(1);
xhrExample({
method: 'POST',
url: 'http://localhost:8000',
onSuccess: (res) => {
console.log(res);
expect(res).toEqual({ name: 'amelia' });
done();
},
});
});
});
Test result:
PASS stackoverflow/71021143/exampleXHR.test.js (7.859 s)
71021143
✓ should pass (37 ms)
console.log
{ name: 'amelia' }
at Object.onSuccess (stackoverflow/71021143/exampleXHR.test.js:28:17)
---------------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
---------------|---------|----------|---------|---------|-------------------
All files | 100 | 100 | 100 | 100 |
exampleXHR.js | 100 | 100 | 100 | 100 |
---------------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests: 1 passed, 1 total
Snapshots: 0 total
Time: 8.41 s