The Best JavaScript Testing Frameworks you should be using in 2021

Automation testing using JavaScript has been gaining popularity in recent days making a blog about the best JavaScript Testing Frameworks available the need of the hour. A conversation between business analysts, developers, and testers about a feature will become specifications. After that, the developers & testers convert the specs into automated acceptance tests. Automated tests help the team to drive the feature development as passing acceptance tests prove the fact that the agreed feature has been developed as expected.

To convert specifications into automated acceptance tests, devs & QAs should use the same programming language. Let’s say your team is using JavaScript for development and Java for automation testing. In this case, you won’t be able to enable effective collaboration between the developers & testers which is a big concern. Analysts & developers can capture acceptance criteria effectively. However, testers are good at adding edge cases making them invaluable as well. That is why everyone’s involvement right from the beginning is vital with common tools, frameworks, and language.

In this blog article, we have listed the best JavaScript Testing Frameworks which are widely used for writing unit tests and acceptance tests.

Jasmine

When developers focus more on components than features, they don’t add value to the business. Writing tests in plain English helps your team focus on the business goals and Jasmine is one of the best testing frameworks to make it possible. Using Jasmine you can write meaningful tests which can be understood by everyone in the team and help the developers to write higher quality code more efficiently.

Jasmine has support for Node.JS, RUBY, and Python. If you want to run the tests on a Web Browser instead of running them in interpreter/programming engine, then you can go for Jasmine Standalone. Now let’s find out how to use Jasmine in Node.JS beginning right from its installation.

Installation:

To install Jasmine, run the below npm command.

npm install jasmine —save-dev

Initialization

To set up Jasmine in a Node.JS project, you need spec files and jasmine.json (Configuration file). You can add these files manually. However, we have an npx command to initialize Jasmine in your project and it has been listed below

npx jasmine init

After running the above command, you can find the ‘spec’ folder and ‘jasmine.json’ file under the spec->support folder.

Add Jasmine in package.json

Now, you need to inform your node project that you are using Jasmine for testing. Open package.json and update the ‘test’ value as ‘jasmine’ as shown below.

{
  "name": "jasmine-sample",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "jasmine"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "jasmine": "^3.7.0"
  }
}

Describe

In order to group related test cases like how we group scenarios in a feature file in Cucumber, you need to create a JavaScript file and write a ‘describe’ function as shown below.

describe("User Management", ()=>{

})

In the above function, it is a placeholder to add ‘User Management’ related test cases.

Specs

Specs are your test cases. You need to write specs inside the ‘describe’ function as shown below.

describe("User Management", ()=>{

    it("should signup",()=>{

    })

    it("should login", ()=>{

    })
})

As we mentioned earlier, everyone in the team should understand what is the purpose of each test. When naming a test case for unit & acceptance tests, you need to describe what you are expecting. However, it is a cumbersome task for a developer to focus on names. If there are a rule and a standard which come from the testing framework, then the team members will be able to stick to the business goals and focus on achieving them instead of concentrating only on the code components.

That is why the Jasmine framework has the ‘it’ function and the first argument starts with ‘should’. When a test case says ‘It should do something’, the developer will focus on that something throughout the development which is exactly what we want.

How is a spec pass or fail determined? You can have multiple assertion lines inside a spec and even if one of those assertions fails, the spec will be marked as ‘Fail’.

Assertions

Jasmine has an in-built assertion function which is called ‘expect’. Expect function has one argument which takes the actual value. You can also chain the assertion using Matcher functions.

expect(“my string”).toMatch(/string$/) – Expect the actual value to match a regular expression.

expect(bigObject).toEqual( “foo”: ‘bar’, ‘baz’ ) – Expect the actual value to be equal to the expected value using deep equality comparison.

expect(thing).toBe(realThing) – Expect the actual value to be === to the expected value.

Configurations

Jasmine has a total of five configurations in the jasmine.json file. Let’s take a look at the purpose of each of these configurations one by one.

“specdir” – A directory path where you have the specs in the current project directory.

“specfiles” – You can include & exclude spec file paths with regular expression.

“helpers” – Before the test execution commences, you may need some supporting files that should be executed. The helpers config is the placeholder to mention the supporting JS files.

“stopSpecOnExpectationFailure” – This is a boolean config. If the value is true, then the spec execution will be stopped when the first assertion is failed.

“random” – Run the specs in random order.

Advantages of Jasmine

• You can customize the Jasmine report.
• It has a very strong community that supports the users.
• You can even create your own Matchers.
• It is extremely simple and easy to use making it the choice of many developers and testers mainly for its simplicity.

Jest

Jest is also a popular JavaScript Testing framework that works with Node.JS, React, Angular, Vue, Babel, TypeScript, and more. Jest was developed by Facebook and so it runs thousands of tests for Facebook on a daily basis. Apart from Facebook, there are many other prominent companies that also use Jest. So let’s see what makes Jest one of the best JavaScript Testing Frameworks and how you can implement it in your project. Let’s begin with its installation process.

Installation

You can easily install Jest by making use of the below code,

npm install --save-dev jest

Add Jasmine in package.json

Update scripts>test node as ‘jest’ in Package.json as shown below.

{
  "name": "jest-sample",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "jest"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "jest": "^26.6.3"
  }
}

Configuration

No configuration is required to write or run Jest tests. However, every testing framework has its own configuration file. To create a config file, you can run the below command.

npx jest —init

Once you run the above command, Jest will ask you a few questions to create the config file.

Migrating from Jasmine to Jest

If you are planning to migrate from Jasmine to Jest, then we’ve got some good news for you as Jest is compatible with Jasmine tests. This makes the migration far less complicated. However, if you want to do a code-level migration, you can use third-party jest-codemods for the best results.

Assertions

In order to write assertions elegantly in a test, you would definitely need sophisticated Matchers. Jest has a lot of compressive matchers that you could use. However, we have listed some of the commonly used Matchers below.

test('two plus two is four', () => {
  expect(2 + 2).toBe(4);
});

test('object assignment', () => {
  const data = {one: 1};
  data['two'] = 2;
  expect(data).toEqual({one: 1, two: 2});
});

test('null', () => {
  const n = null;
  expect(n).toBeNull();
  expect(n).toBeDefined();
  expect(n).not.toBeUndefined();
  expect(n).not.toBeTruthy();
  expect(n).toBeFalsy();
});

Snapshot Testing

Your Acceptance Tests test the application under test by performing actions on the UI. However, it never validates whether the UI is rendered as same as before and if the CSS styles are applied correctly or not. Jest has a feature to address this issue (i.e. Visual Regression Testing). Using Jest, you can capture snapshots and compare them with the expected snapshot thereby creating a huge advantage if that is your primary need.

Advantages

If you want to run your tests in parallel, then Jest is your go-to testing framework. Jest has numerous assertion functions. In terms of ease of adoption, simplicity, support, and documentation, Jest is hands down the clear winner.

Mocha

Mocha is a JavaScript Testing framework only for Nod.JS. Mocha doesn’t have an in-built assertion library. However, it allows you to use the following libraries such as should.js, chai, expect.js, better-assert, and unexpected for assertions. You can execute tests in two modes (Serial & Parallel).

Conclusion

Jest and Jasmine are the best JavaScript Testing frameworks. However, most of the engineers are comfortable with Jasmine over Jest. As an automation testing company, we use Jasmine for Protractor automation testing. Jasmine is the default testing framework for Protractor. Our suggestion is not final and it shouldn’t influence your framework decision.

Jest has many sophisticated features such as Configuring Visual Testing (i.e. Snapshot Testing) which is not as easy to do in Jasmine. However, in Jest, it is pretty straightforward. Apart from that, test creation and assertions are similar in both these frameworks. If you feel Jest is suitable for your project, please go ahead.