I am trying to figure out how to correctly mock this code. I have figured out how to mock a success, but I cannot figure out how to mock the catch/reject block.
App code:
function getData(url = '') {
return new Promise((resolve, reject) => {
axios
.get(`${baseURL}${url}`)
.then((res) => {
resolve(res.data);
})
.catch((err) => {
reject(err);
});
});
}
in testing I have:
import axios from 'axios';
const MockAdapter = require('axios-moc-adapter');
describe('getData', () => {
it('test success', async () => {
const mock = new MockAdapter(axios);
mock.onGet(`${service.baseURL}/sites`).reply(200, 'success');
const axiosSpy = jest.spyOn(axios, 'get');
const rtn = await service.getData('/sites');
expect(axiosSpy).toHaveBeenCalled();
expect(rtn).toBe('success');
});
it('test failure', async () => {
const mock = new MockAdapter(axios);
mock.onGet(`${service.baseURL}/sites`).networkError();
const rtn = await service.getData('/sites').catch((err) => {
expect(err.message).toBe('message');
});
expect(rtn).toBe(undefined);
});
});
The test success test works, but when I test the failure, I get:
Expected: "message"
Received: "Cannot read properties of undefined (reading 'then')"
29 | mock.onGet(`${service.baseURL}/sites`).networkError();
30 | const rtn = await service.getData('/sites').catch((err) => {
> 31 | expect(err.message).toBe('message');
| ^
32 | });
33 | expect(rtn).toBe(undefined);
34 | });
How can I write a test that successfully passes the failure case? Specifically, I can make this test pass by not checking inside the catch block, but when I run coverage, it doesn't cover the catch block in the App code. How can I correctly cover this line?
Can't reproduce your issue, but .networkError() will throw an error with 'Network Error' message rather than 'message', see source code index.js#L141
service.ts:
import axios from 'axios';
export const baseURL = 'http://localhost:3000/api';
export function getData(url = '') {
return new Promise((resolve, reject) => {
axios
.get(`${baseURL}${url}`)
.then((res) => {
resolve(res.data);
})
.catch((err) => {
reject(err);
});
});
}
service.test.ts:
import * as service from './service';
import axios from 'axios';
import MockAdapter from 'axios-mock-adapter';
describe('getData', () => {
it('test success', async () => {
const mock = new MockAdapter(axios);
mock.onGet(`${service.baseURL}/sites`).reply(200, 'success');
const axiosSpy = jest.spyOn(axios, 'get');
const rtn = await service.getData('/sites');
expect(axiosSpy).toHaveBeenCalled();
expect(rtn).toBe('success');
});
it('test failure', async () => {
const mock = new MockAdapter(axios);
mock.onGet(`${service.baseURL}/sites`).networkError();
const rtn = await service.getData('/sites').catch((err) => {
expect(err.message).toBe('Network Error');
});
expect(rtn).toBe(undefined);
});
it('test failure 2', async () => {
const mock = new MockAdapter(axios);
mock.onGet(`${service.baseURL}/sites`).networkError();
await expect(service.getData('/sites')).rejects.toThrowError('Network Error');
});
});
test result:
PASS examples/69947398/service.test.ts (8.89 s)
getData
✓ test success (5 ms)
✓ test failure (1 ms)
✓ test failure 2 (2 ms)
------------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
------------|---------|----------|---------|---------|-------------------
All files | 100 | 0 | 100 | 100 |
service.ts | 100 | 0 | 100 | 100 | 4
------------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests: 3 passed, 3 total
Snapshots: 0 total
Time: 9.52 s