I am making testing in my NodeJS project and I have the following function I want to unit test:
function myRequest(targetUrl, reqBody) {
return new Promise((resolve, reject) => {
request.post(targetUrl, { json: reqBody }, (error, response, body) => {
if (!error && response.statusCode === 200) {
resolve(body.transferId);
} else {
reject(error || body.description || body);
}
});
});
}
I am using mocha and sinon. How can I test this function?
Firstly, I tested using my own mocked request module for the success scenario. Now, I want to do the error scenario, which could be the post function gets an error. How could I do it without changing or making a new one mock of request (to return an error)? Is is possible?
Here is the unit test solution, you should use sinon.stub
:
E.g.
index.ts
:
import request from 'request';
export function myRequest(targetUrl, reqBody) {
return new Promise((resolve, reject) => {
request.post(targetUrl, { json: reqBody }, (error, response, body) => {
if (!error && response.statusCode === 200) {
resolve(body.transferId);
} else {
reject(error || body.description || body);
}
});
});
}
index.spec.ts
:
import { myRequest } from '.';
import chai from 'chai';
import sinon from 'sinon';
import chaiAsPromised from 'chai-as-promised';
import request from 'request';
chai.use(chaiAsPromised);
const { expect } = chai;
describe('myRequest', () => {
it('should request success', async done => {
// @ts-ignore
const stub = sinon.stub(request, 'post').callsFake((uri, options, callback) => {
const mResponse = { statusCode: 200 };
const mBody = { transferId: 1 };
callback(null, mResponse, mBody);
done();
});
const actualValue = await myRequest('url', {});
// @ts-ignore
stub.calledOnceWith('url', { json: {} });
expect(actualValue).to.eq(1);
stub.restore();
});
it('should throw error use request error', async done => {
const mError = new Error('Internal server error');
const mResponse = { statusCode: 500 };
// @ts-ignore
const stub = sinon.stub(request, 'post').callsFake((uri, options, callback) => {
callback(mError, mResponse, null);
done();
});
await expect(myRequest('url', {})).to.be.rejectedWith(mError);
// @ts-ignore
stub.calledOnceWith('url', { json: {} });
stub.restore();
});
it('should throw error use body.description as error message', async done => {
const mResponse = { statusCode: 500 };
const mBody = { description: 'some error' };
// @ts-ignore
const stub = sinon.stub(request, 'post').callsFake((uri, options, callback) => {
callback(null, mResponse, mBody);
done();
});
await expect(myRequest('url', {})).to.be.rejectedWith(mBody.description);
// @ts-ignore
stub.calledOnceWith('url', { json: {} });
stub.restore();
});
it('should throw error use body as error message', async done => {
const mResponse = { statusCode: 500 };
const mBody = 'some error';
// @ts-ignore
const stub = sinon.stub(request, 'post').callsFake((uri, options, callback) => {
callback(null, mResponse, mBody);
done();
});
await expect(myRequest('url', {})).to.be.rejectedWith(mBody);
// @ts-ignore
stub.calledOnceWith('url', { json: {} });
stub.restore();
});
});
Unit test result with 100% coverage:
myRequest
✓ should request success
✓ should throw error use request error
✓ should throw error use body.description as error message
✓ should throw error use body as error message
4 passing (13ms)
---------------|----------|----------|----------|----------|-------------------|
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s |
---------------|----------|----------|----------|----------|-------------------|
All files | 100 | 100 | 100 | 100 | |
index.spec.ts | 100 | 100 | 100 | 100 | |
index.ts | 100 | 100 | 100 | 100 | |
---------------|----------|----------|----------|----------|-------------------|
Source code: https://github.com/mrdulin/mocha-chai-sinon-codelab/tree/master/src/stackoverflow/58822996