sinon practices

sinon-practices.js

'use strict';

import sinon from 'sinon';
import chai from 'chai';
const assert = chai.assert;

const Database = {
  save: (user, cb) => {
    cb();
  },
};

function setupNewUser(info, callback) {
  const user = {
    name: info.name,
    nameLowercase: info.name.toLowerCase(),
  };

  try {
    Database.save(user, callback);
  } catch (err) {
    callback(err);
  }
}

describe('SINON SPY', () => {
  let save;
  beforeEach(() => (save = sinon.spy(Database, 'save')));
  afterEach(() => save.restore());

  it('should call save once', () => {
    setupNewUser({ name: 'test' }, () => {});
    assert(save.calledOnce);
  });

  it('should pass object with correct values to save', () => {
    const info = { name: 'test' };
    const expectedUser = {
      name: info.name,
      nameLowercase: info.name.toLowerCase(),
    };

    setupNewUser(info, () => {});
    assert(save.calledWith(expectedUser));
  });
});

describe('SINON STUB', () => {
  let save;
  beforeEach(() => (save = sinon.stub(Database, 'save')));
  afterEach(() => save.restore());

  it('should pass object with correct values to save', () => {
    const info = { name: 'test' };
    const expectedUser = {
      name: info.name,
      nameLowercase: info.name.toLowerCase(),
    };

    setupNewUser(info, () => {});
    assert(save.calledWith(expectedUser));
  });

  it('should pass the error into the callback if save fails', () => {
    const expectedError = new Error('oops');
    const callback = sinon.spy();

    save.throws(expectedError);

    setupNewUser({ name: 'foo' }, callback);
    assert(callback.calledWith(expectedError));
  });

  it('should pass the database result into the callback', () => {
    const expectedResult = { success: true };
    const callback = sinon.spy();

    save.yields(null, expectedResult);

    setupNewUser({ name: 'foo' }, callback);
    assert(callback.calledWith(null, expectedResult));
  });
});

describe('SINON MOCK', () => {
  it('should pass object with correct values to save only once', () => {
    const info = { name: 'test' };
    const expectedUser = {
      name: info.name,
      nameLowercase: info.name.toLowerCase(),
    };
    const database = sinon.mock(Database);
    database.expects('save').once().withArgs(expectedUser);

    setupNewUser(info, () => {});

    database.verify();
    database.restore();
  });
});