Intercept axios request when testing - node.js

Question

I am testing a software and I would like to verify that the request being sent to an API has the correct data. This particular method creates a request with certain data, headers etc. and then makes the request to an external API via axios. Example code:
myFunction() {
const data = {
example: 'my data'
};
const headers = {
'content-type': 'application/json'
}
const request = {
method: 'POST',
baseUrl: 'http://myawesome-site.com',
url: '/api/path',
headers,
data,
}
return axios(request)
.then(res => ...do something)
.catch(err => ...do something else)
}
I would like to know if there is a way using chai or sinon to intercept the axios call and get access only to the "request" object to just verify the data being sent, I don't care about the response.

Answer 1

Here is an unit test solution, you should use sinon.stub:
When you want to prevent a specific method from being called directly (possibly because it triggers undesired behavior, such as a XMLHttpRequest or similar
E.g.
index.ts:
import axios, { AxiosRequestConfig } from 'axios';
exports.myFunction = function myFunction() {
const data = {
example: 'my data'
};
const headers = {
'content-type': 'application/json'
};
const request: AxiosRequestConfig = {
method: 'POST',
baseURL: 'http://myawesome-site.com',
url: '/api/path',
headers,
data
};
return exports
.axios(request)
.then(res => console.log('do something'))
.catch(err => console.log('do something else'));
};
exports.axios = axios;
index.spec.ts:
const mod = require('./');
import sinon from 'sinon';
import { expect } from 'chai';
describe('myFunction', () => {
afterEach(() => {
sinon.restore();
});
it('should send request', async () => {
const mResponse = { status: 200 };
const axiosStub = sinon.stub(mod, 'axios').resolves(mResponse);
const logSpy = sinon.spy(console, 'log');
await mod.myFunction();
expect(
axiosStub.calledWith({
method: 'POST',
baseURL: 'http://myawesome-site.com',
url: '/api/path',
headers: {
'content-type': 'application/json'
},
data: {
example: 'my data'
}
})
).to.be.true;
expect(logSpy.calledWith('do something')).to.be.true;
});
it('should handle request error', async () => {
const mError = new Error('network error');
const axiosStub = sinon.stub(mod, 'axios').rejects(mError);
const logSpy = sinon.spy(console, 'log');
await mod.myFunction();
expect(
axiosStub.calledWith({
method: 'POST',
baseURL: 'http://myawesome-site.com',
url: '/api/path',
headers: {
'content-type': 'application/json'
},
data: {
example: 'my data'
}
})
).to.be.true;
expect(logSpy.calledWith('do something else')).to.be.true;
});
});
Unit test result with 100% coverage:
myFunction
do something
✓ should send request
do something else
✓ should handle request error
2 passing (14ms)
---------------|----------|----------|----------|----------|-------------------|
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/57807855