mocha and chai code example

Example 1: mocha js

Mocha is a JavaScript test framework!

var assert = require('assert');
describe('Array', function () {
  describe('#indexOf()', function () {
    it('should return -1 when the value is not present', function () {
      assert.equal([1, 2, 3].indexOf(4), -1);
    });
  });
});

Example 2: what is mocha js

Mocha is javascript test framework!

Example 3: how to run mocha tests on asynchronous functions in script

// async/await
it('responds with matching records', async function() {
  const users = await db.find({ type: 'User' });
  users.should.have.length(3);
});

// promise.then()
it('should save without error', function(done) {
  var user = new User('Luna');
  user.save(function(err) {
    if (err) done(err);
    else done();
  });
});

Example 4: chai js

Chai is an assertion library with 3 different assert styles,
namely "should", "expect" and "assert".

foo.should.equal('bar');	 // Should style
expect(foo).to.equal('bar'); // Expect style
assert.equal(foo, 'bar');	 // Assert style

It can be used to replace the default assertion styles of JavaScript testing frameworks.