can't mock constructor using sinon and proxyquire - node.js

Question

I've looked at several similar questions but none of the cases fit my problem. I'm trying to mock a constructor, which I've done in other tests, but I can't get it to work in the case of using google-auth-library
code.js
const {OAuth2Client} = require('google-auth-library');
const keys = require('./oauth2.keys.json');
async function getRedirectUrl() {
const oAuth2Client = new OAuth2Client(
keys.installed.client_id,
keys.installed.client_secret,
keys.installed.redirect_uris[0]
);
const authorizeUrl = oAuth2Client.generateAuthUrl({
access_type: 'offline',
scope: 'https://www.googleapis.com/auth/bigquery',
prompt: 'consent'
});
return authorizeUrl;
}
test.js
let Code = require('../code.js');
describe('code', function() {
let generateUrlStub, tokenStub, mockClient;
before(async () => {
generateUrlStub = sinon.stub().returns('http://example.com');
tokenStub = sinon.stub().returns({tokens: 'tokens'});
mockClient = sinon.stub().returns({
generateAuthUrl: generateUrlStub,
getToken: tokenStub,
});
Code = proxyquire('../Code.js', {
'google-auth-library': mockClient,
});
});
it('should call generateAuthUrl', async function() {
const output = await Code.getRedirectUrl();
sinon.assert.called(generateUrlStub)
});
});

Answer 1

Here is the unit test solution:
const { OAuth2Client } = require("google-auth-library");
const keys = {
installed: {
client_id: "1",
client_secret: "client_secret",
redirect_uris: ["http://example.com/callback"]
}
};
async function getRedirectUrl() {
const oAuth2Client = new OAuth2Client(
keys.installed.client_id,
keys.installed.client_secret,
keys.installed.redirect_uris[0]
);
const authorizeUrl = oAuth2Client.generateAuthUrl({
access_type: "offline",
scope: "https://www.googleapis.com/auth/bigquery",
prompt: "consent"
});
return authorizeUrl;
}
module.exports = { getRedirectUrl };
index.spec.js:
const proxyquire = require("proxyquire");
const sinon = require("sinon");
const { expect } = require("chai");
describe("code", function() {
let generateUrlStub, tokenStub, code;
beforeEach(() => {
generateUrlStub = sinon.stub().returns("http://example.com");
tokenStub = sinon.stub().returns({ tokens: "tokens" });
code = proxyquire("./", {
"google-auth-library": {
OAuth2Client: sinon.stub().callsFake(() => {
return {
generateAuthUrl: generateUrlStub,
getToken: tokenStub
};
})
}
});
});
afterEach(() => {
sinon.restore();
});
it("should call generateAuthUrl", async function() {
const output = await code.getRedirectUrl();
expect(output).to.be.eq("http://example.com");
sinon.assert.called(generateUrlStub);
});
});
Unit test result with 100% coverage:
code
✓ should call generateAuthUrl
1 passing (216ms)
---------------|----------|----------|----------|----------|-------------------|
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s |
---------------|----------|----------|----------|----------|-------------------|
All files | 100 | 100 | 100 | 100 | |
index.js | 100 | 100 | 100 | 100 | |
index.spec.js | 100 | 100 | 100 | 100 | |
---------------|----------|----------|----------|----------|-------------------|
Source code: https://github.com/mrdulin/mocha-chai-sinon-codelab/tree/master/src/stackoverflow/58955304