NodeJS testing with Mocha and Should

Jan 16, 2013

There are a lot of frameworks to include tests in your projects, one popular choice is Mocha and the Should package for the assertion syntax.

Links:

Mocha Should

Installation

npm install -g mocha npm install should

(-g flag used to install mocha globally so it will be possible to use the mocha executable from anywhere)

Assertions with Should.

Should is a NodeJS module that makes it easy to declare assertions in a kind of natural language. It will throw an exception if the code does not comply with them.

	var should = require('should');
	var testobj = {
	name:"Mary",
	age:29,
	company:"none",
	email:"mary@mary.com",
	properties:[
	{
	"name":"Lake house",
	"value":100000
	}
	]
	};
	//This should pass (no exception will be thrown)
	testobj.should.have.property("name");
	testobj.age.should.be.above(20);
	testobj.company.should.be.a("string");
	testobj.properties.should.not.be.empty;
	//This will throw an exception
	testobj.properties.length.should.be.within(10,20);

view raw should_syntax.js hosted with ❤ by GitHub

Check the should.js documentation or source for all the features.

Using Mocha and Should

In the following snippet a fake Validator component will be tested

	var mocha = require('mocha');
	var should = require('should');
	//Our fake validation component
	var Validator = {
	validateName:function(name){
	if (typeof name !== 'string')
	return false;
	if(name.length==0)
	return false;
	return true;
	}
	}
	//The test suite
	describe('Validator',function(){
	var testName,valid;
	it('should not accept invalid types',function(done){
	testName = 123;
	valid = Validator.validateName(testName);
	valid.should.be.false;
	done();
	});
	it('shoud not accept empty string',function(done){
	testName = '';
	valid = Validator.validateName(testName);
	valid.should.be.false;
	done();
	});
	it('should accept valid strings',function(done){
	testName = 'Valid Name';
	valid = Validator.validateName(testName);
	valid.should.be.true;
	done();
	})
	})

view raw mocha_test.js hosted with ❤ by GitHub

Running the tests with mocha executable

If you invoke mocha from the command line, it will search for a file called tests.js or a directory called tests. You can also specify the name of the test file as:

mocha mytestfile.js

Presenting the results

Mocha has a parameter called ‘reporter’ that allows to get the results in different formats. To list all the avalaible reporters use

mocha --reporters

Using the spec reporter

mocha -R spec mochatest.js

We will get the following: