5 Powerful Test-Driven Development Tools (+ Tutorial)

Software is a crucial component of every modern business.

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by Matias Emiliano Alvarez Duran


One single bug can badly hurt your company:

  • If your website takes too long to load, it’ll cause possible customers to close your tab

  • If your placed orders get lost forever, you’ll upset customers and build a bad reputation

  • If your app is glitchy, fewer people will use it

The problem with bugs is that they cause your programmers to be overworked with continuous short-term fixes. That means they’ve zero capacity to work on bigger projects or fix the root cause of the issue. 

But test-driven development (TDD) can help. In this article, we’ll talk you through how to use tools like JUnit, Mockito, and Jest, and give you everything you need to give your team a smooth introduction to TDD.

Table of contents 

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What is a test-driven development tool?

Test-driven development tools or unit testing frameworks are systems that help you test and improve your code performance. These tools allow Software Developers and QA Automation Engineers write, and run unit tests in the same place. 

TDD is an Agile, test-first approach to software development. It’s iterative and promotes high code coverage. 

Why should your team use TDD tools?

Test-driven development is one of the many Agile technical practices. It can be a time-consuming process at first, but it provides a high return on investment in the long term. 

Developers need to write unit tests for every functionality and it can slow down the process initially. In the long term, TDD tools help them to:

  • Simplify the software development process

  • Reduce time spent coding and debugging 

  • Learn from best practices 

  • Simplify production code

  • Collaborate with other developers

  • Build a bank of code that can be reapplied in other projects

  • Learn how to carry out complex actions

  • Spot weaknesses in internal security 

  • Increase the quality of the source code

  • Verify conditional loops functionality

  • Focus on continuous improvement

What about behavior-driven development (BDD)?

Behavior-driven development is a different approach to software testing. While TDD places its focus on unit tests; BDD focuses on end-to-end testing. That means TDD evaluates code against its functionality, while BDD does it against the user experience. 

To sum up test-driven development vs behavior-driven development, TDD validates that a piece of code is doing what it’s supposed to do under certain predefined scenarios, while BDD only validates whether a simulated end-user was able to perform the expected behavior. 

Understanding the test pyramid

Testing is a crucial component of the Agile software development lifecycle. It’s one of those practices that makes Agile iterative and focused on continuous improvement.

The testing pyramid is a concept that illustrates the different approaches to functional testing in software development. From bottom to top, this pyramid explains:

  • Unit

  • Integration

  • End-to-end tests

The bottom part of the testing pyramid (unit and integration) usually relies on automated testing; while the upper part (E2E) needs more manual intervention.

Unit tests 

Unit tests have a small scope, testing isolated units of code for every function of the software. They sit at the base of the pyramid.

TDD uses unit testing because it follows the principle that if every unit passes its test, then, the application should work as expected. 

For example, let’s say that you’re building a signup form on a website. You need users to be able to sign up, but first you must: 

  • Check that a given username respects a system predefined format

  • Check that a given email has a valid format

  • Check that a given password is secure enough based on the chosen characters

Integration tests

These go in the middle of the pyramid. Integration tests verify that different components or modules of the system interact with each other successfully. 

Integration tests usually happen after unit tests to ensure that the main flows of the application do what they are supposed to do. Because the TDD approach is isolated and each test verifies internal functionality without interacting with other pieces of code.

Following the previous example, an integration test of the signup form page checks to see if: 

  • Code a function to check the new user information against the database to ensure there aren’t any duplicates

  • Create a new user entry in the database

  • Code an algorithm that creates a confirmation code and assigns it to individual accounts

End-to-end tests

End-to-end tests are at the top of the pyramid. These tests usually perform several automated steps to make sure that a certain flow works as expected. BDD uses this type of testing and evaluates the critical flows of a software application. 

Following the same previous example, these are some steps that can be addressed:

  • Create a new user filling out incorrect information

  • Create a new user filling out correct information

  • Make sure the new user can log in to the system

5 best test-driven development tools for Agile teams 

The best test-driven development tools are the ones that help software developers code and run unit tests without any hassle. They contain extensive information on the programming language they use and help developers code better and faster. 

Check out these five tools that make the TDD process and unit testing easier.

1. JUnit 

With JUnit, you can see the results of a test and even examine the reason behind failures via the “click to see difference” link. Source: Kotlin

JUnit is an open-source testing framework designed for programming in Java. It contains libraries that help developers define and execute unit tests. The following features make JUnit great for TDD:

  • Libraries are consistently updated by other developers

  • It’s easy to test the business logic of any class

  • The platform supports testing data from integrated development environments (IDE) or command lines. 

“We use JUnit 5 to manage testing sessions,” said Diego Martinez, software developer at NaNLABS.  “Especially as a provider of utilities to build assertions in an abstract way and make the use of interfaces more fluid. It helps us enhance expressiveness and readability.” 

2. Mockito 

Mockito is a back-end Java framework that allows developers to carry out tests like creating a mock object. Source: https://facingissuesonit.com/

Mockito is also a Java framework that helps developers write certain types of tests. It also lets you test data from IDEs or command lines. Other Mockito features include:

  • Allowing developers to write tests that follow the “arrange/act/assert” approach

  • Using a simple and readable syntax

  • Being user-friendly

  • Can also be used for BDD tests

“Mockito provides high-level instrumentation, which makes it easy to collaborate. It’s useful to optimize unit test programming while focusing on the functions we’re trying to test,” explained Diego Martinez. 

3. Jest

This promotional screenshot from Jest shows a simple diff test case that failed to illustrate how it will show your test results. Source: Jest

Jest is a testing tool that helps developers create unit tests in JavaScript. It’s commonly used in front-end codebases but it could also be used for any JavaScript project. The NaNLABS team uses Jest because: 

  • It shares test results fast since several tests run simultaneously.

  • Allows developers to structure, write code and run JavaScript TDD unit tests.

  • It’s easy to set up and use. 

  • It runs tests in different environments to avoid two tests interfering with each other

  • It also supports TypeScript.

4. MochaJS

The MochaJS bash screen shows the status of the tests you’re running in milliseconds. Source: MochaJS

Mocha is a TDD unit testing tool that also works with JavaScript. It runs on Node.js but is also accessible through the web. Some of its main features include:

  • Runs on a browser

  • Runs asynchronous tests

  • Alerts/highlights tests that are running slow

  • Runs tests in parallel

  • Provides test coverage reports.

5. Pytest

This assertion example from Pytest represents how differences are highlighted within the app. Source: PyPi

Pytest is an open-source testing framework that allows you to improve the quality of your Python programs. These are some of its identifying features:

  • It’s easy to use

  • Supports tests code from command-lines

  • Experienced and active community for support

  • Can run several tests in parallel

Other useful testing tools for integration tests and BDD

There are some testing tools that help developers work on other forms of testing.  

  • For integration testing: TestContainers and Spring Tests.

  • For end-to-end tests (BDD): Cypress, Selenium, Webdriver, Cucumber.

What makes a good testing framework? 

Testing frameworks are good as long as developers find them useful. The best testing tools or frameworks are:

  • Adaptable. Tools that are modular and adaptable to changes. 

  • Applicable to different scenarios. Makes it easy for developers to access reusable components, common methods, and utilities.

  • Consistent. Uses the same format for all the written tests in the test suite.

  • Independent. All test scripts should be able to be used independently from one another. 

  • Able to send timely reports. After developers finish writing code scripts, the tool should send them a report with results over email. 

  • Integratable. Allows integrations with different applications.  

How do I introduce my team to TDD tools?

The great thing about TDD tools is that your team has probably already done the hard part: write the code. Changing the use case to write test code and running it will be easy. 

But getting your development team onboard with TDD can also be a challenge, especially if they’re already packed with work and constantly putting out fires. In those cases, learning a new skill or taking a step back to implement a new practice sounds unrealistic and falls to the bottom of their priorities. 

The easiest way to seamlessly incorporate TDD into your software development culture is by augmenting your team with Agile pods or hiring consulting services. 

You don’t need to undergo Agile transformation to start using TDD. Partnering with a NaNLABS Agile pod allows your team to learn from our experienced programmers’ best practices. TDD will quickly become part of their day-to-day work without extra effort.

Ready to build your own custom software with a team that cares about you and your processes? We’re not code monkeys, we care about

Test-driven development tutorial for Agile teams

Test-driven development is easier than you think. We’ll show you how it works in this short video:

Put your knowledge to the test!

Test-driven development is a choice. But if you want high-quality software and have time, money, and the right team, then it’s a must.

At NaNLABS, we like to use tools like Mocha, Pytest, and JUnit to implement TDD, because of their simplicity, velocity, and large libraries.

It’s time for you to implement TDD in your business and test those tools for yourself. Don’t worry if you don’t have the time or skills in-house, just augment your team with NaNLABS Agile pods, and leave the rest to us!

Ready to build your own custom software with a team that cares about you and your processes? We’re not code monkeys, we care about

Frequently asked questions about test-driven development tools

  • What is test-driven development? 

    Test-driven development (TDD) is an Agile technical practice that has a test-first approach to software development. The TDD cycle has three stages: 

    1. Red: write a unit test, run it, and expect it to fail

    2. Green: write enough code to meet the test functionality and make it pass

    3. Refactor: refactor code to make it modular and simple. Repeat the process with the next part of the feature. 

  • What are Agile technical practices?

    Agile technical practices are ways of bringing the Agile methodology to life. Following practices will

    • keep your code bug-free and clean,

    • reduce your time-to-market,

    • increase code coverage,

    • and improve productivity and team engagement. 

    Among the most common technical practices are TDD, reducing technical debt, Agile continuous integration, and extreme programming.

  • What are unit tests in TDD?

    Unit tests in TDD are a software development testing technique that allows you to evaluate single units of code. The idea is to break a feature into smaller units and test them individually. TDD expects that if every unit test passes, then, the overall feature or software will work properly.

  • What is refactoring in Agile?

    Refactoring code in Agile is the practice of rewriting code to simplify it as much as possible. The result of refactoring is software that’s modular, clean, tidy, and simple. 

  • Can TDD tools be used for BDD?

    It’s not possible to use TDD tools for BDD since they do two different types of testing. Cucumber, Cypress, and Selenium are other BDD tools.

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