I am trying to test my function using Sinon stubs and mocks, but I am getting an error. Please suggest me right technique to write it

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In this module I want to test searchAll function which is calling findAll function of some other module, so I am trying to stub findAll function of the other module and mock the res in my test.js module.

UseControllerModule.js

exports.searchAll = (req, res) => {
    Users.findAll((err, data) => {
        if (err)
            res.status(500).send({
                message: err.message || "Some error occured while retrieving data",
            });
        else res.send(data);
    });
};

The findAll function of the other module has userid parameter which has been stubbed.

So after stubbing and getting the value in response I am trying to mock response here, but it is not running. Mock verifications are causing errors. If I remove verifications, the test cases pass but it does not increment any test coverage.

Test.js

describe("searchAll", function() {
    let res;

    beforeEach(() => {
        res = {
            json: function() {},
        };
    });

    it("should return all the id's of  members of the club", async function() {
        const stubvalue = {
            userid: faker.random.uuid(),
        };
        const mock = sinon.mock(res);
        mock.expects("json").withExactArgs({
            data: stubValue
        });

        const stub = sinon.stub(UserModel, "findAll").returns(Stubvalue);
        const user = await UserController.searchAll();
        expect(stub.calledOnce).to.be.true;
        mock.verify();
        stub.restore();

    });
});

1 thought on “I am trying to test my function using Sinon stubs and mocks, but I am getting an error. Please suggest me right technique to write it”

  1. You should use stub.callsFake(fakeFunction); to provide a fake implementation for UserModel.findAll() method. It accepts a callback parameter, so you need to execute it and pass the stubvalue to that callback in your fake implementation manually.

    UseControllerModule.js:

    const Users = require('./UserModel');

exports.searchAll = (req, res) => {
  Users.findAll((err, data) => {
    if (err) {
      res.status(500).send({
        message: err.message || 'Some error occured while retrieving data',
      });
    } else {
      res.send(data);
    }
  });
};

    UserModel.js:

    module.exports = {
  findAll(callback) {
    console.log('real implementation');
    callback(null, 'real data');
  },
};

    UseControllerModule.test.js:

    const sinon = require('sinon');
const { expect } = require('chai');
const UserModel = require('./UserModel');
const UserController = require('./UseControllerModule');

describe('searchAll', function () {
  let res;

  beforeEach(() => {
    res = {
      send: function () {},
    };
  });

  it("should return all the id's of  members of the club", async function () {
    const stubvalue = {
      userid: '123',
    };
    const mock = sinon.mock(res);
    mock.expects('send').withExactArgs(stubvalue);

    const stub = sinon.stub(UserModel, 'findAll').callsFake((callback) => {
      callback(null, stubvalue);
    });
    UserController.searchAll({}, res);
    expect(stub.calledOnce).to.be.true;
    mock.verify();
    stub.restore();
  });
});

    unit test result:

      searchAll
    ✓ should return all the id's of  members of the club


  1 passing (6ms)

------------------------|---------|----------|---------|---------|-------------------
File                    | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
------------------------|---------|----------|---------|---------|-------------------
All files               |   66.67 |       25 |   66.67 |   66.67 |                   
 UseControllerModule.js |   83.33 |       25 |     100 |   83.33 | 6                 
 UserModel.js           |   33.33 |      100 |       0 |   33.33 | 3-4               
------------------------|---------|----------|---------|---------|-------------------
    Reply

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