CODEWITHSUNDEEP
node.jsmocha.jssinonstub
Talita
Talita

Reputation: 835

Sinon stub undefined with node.js and mocha tests

I want to mock a method of ES6 class.

I am importing models module:

// test.js
const models = require(path.resolve('./models'));

In models folder there is an index.js and it redirects to index.js in user folder while calling models.user:

// models/index.js
models.user = user;

Then I have a user class in index.js: // models/user/index.js

class User extends Model {
  // simplified exists - it returns boolean or thows an error
  static async exists(username) {
    if (username) {
      returns true
    } else {
      throw new Error('bad output');
    }
  }
}

I want to stub exist(username) method with sinon stub.

I am doing:

const sinon = require('sinon');
const models = require(path.resolve('./models'));

describe.only('generateTokenBehavior()', function() {
    it('should return 200 given valid username and password', function() {
        ...
        const stub = sinon.stub();
        stub(models.user.prototype, 'exists').callsFake(true);
        ...
    });

and I am getting an error on the line with stub:

 TypeError: Cannot read property 'callsFake' of undefined

What is wrong with this code? I was researching this problem on similar stack questions but didn't find the answer.

Upvotes: 1

Views: 11885

Answers (1)

Tristan Hessell
Tristan Hessell

Reputation: 950

The problem here is that calling the result of sinon.stub() as a function returns undefined.

const sinon = require('sinon');
const models = require(path.resolve('./models'));

describe.only('generateTokenBehavior()', function() {
    it('should return 200 given valid username and password', function() {
        ...
        const stub = sinon.stub(models.user.prototype, 'exists').callsFake(true);
        ...
    });

For reference, the documentation is here: http://sinonjs.org/releases/v4.1.1/stubs/#properties

I don't blame you for writing it the way you did - the documentation is a bit misleading.

Upvotes: 2

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