How to assert not null?

Question

I'm very new in javascript testing, I would like to know how to assert not null in Mocha framework.

Answer 1

Mocha supports any assertion library you want. You can take a look at how it deals with assertions here: http://mochajs.org/#assertions. I don't know which one you want to use.

Considering you are using Chai, which is pretty popular, here are some options:

Consider "foo" to be the target variable you want to test

Assert

var assert = chai.assert; assert(foo) // will pass for any truthy value (!= null,!= undefined,!= '',!= 0) // or assert(foo != null) // or assert.notEqual(foo, null); 

In case you want to use assert, you don't even need Chai. Just use it. Node supports it natively: https://nodejs.org/api/assert.html#assert_assert

Should

var should = require('chai').should(); should.exist(foo); // will pass for not null and not undefined // or should.not.equal(foo, null); 

Expect

var expect = chai.expect; expect(foo).to.not.equal(null); // or expect(foo).to.not.be.null; 

PS: Unrelated but on Jest there is a toBeNull function. You can do expect(foo).not.toBeNull(); or expect(foo).not.toBe(null);

Answer 2

This is what worked for me (using Expect library with Mocha):

expect(myObject).toExist('Too bad when it does not.');