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Java Testing Tools: 10 Best Practices for Writing Test Cases

Headshot of William McMullin, Solution Architect at Parasoft
August 5, 2021
9 min read

Java testing is a crucial element of knowledge for Java programmers. Here's a breakdown of how you can be a pro in java testing using Parasoft’s Jtest framework.

It’s difficult to imagine where today’s Big Data and Machine Learning projects would be without Java. It’s been over 25 years since it was designed to provide dynamic capabilities that weren’t typically available in traditional compiled languages. It’s now one of the most widely used server-side languages for back-end and front-end development projects.

With such a large active community, Java has maintained its position among the world’s top three most popular programming languages over the years. Java has been so successful because its technology standards have continued to evolve and Java will continue to maintain its popularity without a formidable competitor.

Locating and fixing infrastructure issues during the source code development stage is by far the most efficient and cost-effective way to resolve problems and improve the quality and functionality of the code. If deploying some of the widely used test methods can resolve problems in the code during the development stage, Why aren’t teams budgeting or allocating enough resources for testing?

What’s covered in this blog post:

  1. Be an Expert Java Developer — Learn How to Test
  2. Why Is Java Testing Good for Programmers to Know?
  3. Test Methods for Java
  4. Why Is Unit Testing so Important?
  5. Unit Test Frameworks for Java
  6. How to Write a JUnit Test Case
  7. Unit Testing Gets Better With Automation
  8. Make Java Testing Simpler and Easier With AI
  9. Security Testing in Java
  10. Final Thoughts About Java Testing

Be an Expert Java Developer — Learn How to Test

An exceptional understanding of software testing and testing frameworks separates expert Java developers from novice coders. As critical as speed-to-market is for all software development, testing cannot cause delays. There’s always a balance between quality and speed when testing. Many young developers quickly learn that Java testing is one of the first tasks they’re given after they’ve landed that first big job. Unfortunately, software testing, particularly in Java, isn’t taught in school. That means young developers have to scramble to learn how to create and execute software tests.

Java testing can be frustrating for new programmers and a nuisance for more experienced developers. Young developers may not understand what the code is designed to do, especially if they receive undocumented or unstable legacy code. Testing requires a lot of abstract thinking and it takes time to create and fix tests. It’s a big lift for young developers who haven’t done much testing at all. Also, there are so many scenarios for why something in the code isn’t working and it can take days or weeks to figure out where the bugs are.

Experienced developers don’t like running tests for the same reasons. They’re far more interested in implementing new features because it’s simply more fun to do. They also know that for a large amount of code, a long series of tests are needed. It can take days or weeks to create and execute a full suite of tests.

The entire process can be overwhelming. One of Parasoft’s solution architects breaks down software testing in an excellent software testing tutorial with examples.

How to Write Test Cases for Software: Examples & Tutorial

The blog post addresses questions developers often have about test methods:

  • What is a test case?
  • Test script vs. test case
  • Different test case types
  • How to write software test cases
  • Standard test case format
  • Test case writing best practices
  • Test suite vs. test plan
  • Test case writing tools

New and experienced developers alike can learn best practices for writing tests, standard test case formats, test case writing tools, and more. We want developers to embrace the wonders of software testing so it becomes a less tedious task instead of a serious time and energy drain.

Why Is Java Testing Good for Programmers to Know?

Errors can sometimes be very benign, but it’s far more often than not, that errors can cause serious consequences. You simply can’t ignore it. Finding out what doesn’t work can be painful because of all the possibilities that exist: there have been updates to the code and you’re not working in the latest version, a third-party dependency may have been shut down, or a background app may make a test fail, etc. All of this impacts new tests and these types of errors can take days or weeks to resolve.

Some of the most inconceivable things can happen even when you follow best practices. The smallest details require your full attention. Software testing is so much easier to manage if something goes wrong when you give it your full attention. The devil is always in the details. For example, you’ll know when an app didn’t start because it was stated in an error message you set up. If the app has dependencies mocked out, the error messages will be revealed in a log or in the terminal. Again, it’s all in the details.

Building and maintaining readable test code establishes good test coverage and avoids a breakdown of code during post-development feature implementation. Although there are no shortcuts, there are things that can make your Java testing easier, better, and more efficient overall.

Test Methods for Java

There are several ways to test a Java app.

  • Benchmark measures the efficiency of the code.
  • Integration checks the compatibility and consistency of a group of modules or a whole application.
  • Protocol tests different protocols.
  • Mutation identifies missing tests within the code.
  • Database test for schema, security, and performance among others.
  • Performance also known as stress testing, determines what load an app can handle.
  • Security tests for the vulnerability of security protocols.
  • UI the user interface is mostly tested by QA engineers.
  • Unit verifies that each app function returns the correct value for a given input.

Four types of testing are often considered more important than others:

  1. Unit testing
  2. Integration testing
  3. Interface testing
  4. Security

Unit and integration testing are the two most important tests. These allow for independent tests of all the functionality. It is critical for Java testing because it’s the best way to determine if the software fails. Security testing will be covered in another section.

Why Is Unit Testing So Important?

The entire rationale behind running tests is to find errors. Who wouldn’t agree that finding an error in a particular piece of the code is better than finding that there are errors in the entire app? That means you’d have to dig in to figure out where the errors are. That could take days or weeks, maybe months. The reason we do unit testing is to segregate the code to find and fix errors. In the end, you will develop code that is more reliable and bug-free.

Unit testing is agile. Old code will oftentimes need to be updated as new features are added. By running tests on the new code, you will be able to determine whether or not the new code has broken an old feature.

If you don’t do unit testing in isolation, things can change without your knowledge. Your new tests will fail and you don’t know why. If the unit tests are difficult to write, chances are that it’s not about the test – it’s about the software itself. It takes time to do create new tests, but it’s the singular thing that can be done during development to ensure that the software accomplishes what it’s designed to do.

Unit Test Frameworks for Java

Testing frameworks are the software tools that help programmers write and run unit tests. It standardizes the way web applications are built by providing a foundation for testing along with the ability to execute tests and report results. Simply put, these testing frameworks make the lives of programmers so much easier.

Unit testing frameworks supply pre-written code and often include tools, libraries, compilers, and APIs. JUnit is one of the most widely adopted open source unit testing frameworks. TestNG is another popular open source unit testing framework, and many others provide more specific purposes. Here’s a list of some other commonly used frameworks.

  • JBehave
  • Serenity
  • Selenide
  • JWebUnit
  • Gauge
  • Geb
  • Spock
  • Mockito
  • PowerMock

How to Write a JUnit Test Case

How to write unit tests? When conducting Java testing, test cases are generated for the source code. It’s executed using various parameters to make sure the code will work against every possible scenario. Java testing provides thorough and functioning test cases that can test every aspect of your application.

A JUnit test case is exactly what it sounds like: a test scenario measuring functionality across a set of actions or conditions to verify the expected result. JUnit is a simple framework to write repeatable tests. Because JUnit is one of the most popular and important test frameworks for test-driven development, it’s worthy of discussion here.

Those who are new to Java must learn to be efficient and optimize test cases while writing code. If you write code without test cases, there’s just no quality control. The test code is written to verify that the application works the way you want it to. Test cases must be run once they’ve been written to ensure the code works when the results are checked.

With test-driven development, the unit test must be written and executed before any code is written. Once the code is written, all tests should be executed and the code should pass. Tests should be executed each time any code is added to make sure nothing is broken.

JUnit uses annotations such as @After, @Test(timeout = 1000) for timeout, etc. It allows you to execute multiple tests together, check which exception is thrown from the test, and complete parameterized testing. It will also terminate a test that takes longer than the specified time within milliseconds. Users can configure and set up tests the way they want them to be by using more JUnit test annotations.

Unit Testing Best Practices Cheat Sheet

Here’s a quick cheat sheet for best practices for unit testing:

  1. Write the test.
  2. Determine the method for the test.
  3. Complete a baseline test to determine the parameters.
  4. Create a test method to meet the test’s requirements.
  5. Execute the test, ensure that it runs correctly to determine the intended output.
  6. Review to ensure successful execution. Check that all the lines are covered and that everything is executed.
  7. Go to the next method.

These steps are repeated until the functionality of the program is complete.

JUnit Tutorial: Setting Up, Writing, and Running Java Unit Tests

In the JUnit Tutorial, you’ll learn about running tests, regression testing, JUnit4, JUnit5, the anatomy of a JUnit, how to run Junit from the command line, from the IDE (Eclipse and IntelliJ), and using build systems (Maven and Gradle).

Unit Testing Gets Better With Automation

The key to speedy and efficient unit testing is automation. Automated testing tools can help reduce late-cycle defects that allow developers to focus on new feature development. Developers can easily generate, augment, and reuse unit tests while optimizing the execution of those tests to substantially reduce the amount of time and cost associated with unit testing. This means you can run tests in hours rather than weeks or months.
When unit testing can be done this rapidly through automation, it can be adopted as a best practice and scaled across the enterprise. Project managers can set guidelines for coding standards and statistical quality control measures. Running tests for Java projects will be more uniform and faster.

Make Java Testing Simpler and Easier With AI

Automated artificial intelligence (AI) provides the power to create unit tests for you with one-click automatic JUnit test case creation. It allows you to seamlessly integrate tests into your continuous integration process. The unit test assistant will automatically guide you through insertions with intelligent recommendations.

Mocking is a feature that allows you to replace dependencies that are slow or unavailable. This will greatly speed up your unit testing. With an AI-powered approach to unit testing, you can be alerted about mockable objects, while instantly mocking those objects for you.

AI can also help with scaling tests. Bulk unit test creation generates multiple tests instantly. It will create tests for multiple classes within a package or project. Increasing code coverage is important when testing in JUnit. Test case parameterization can test different variables and code paths in your application.

As for test execution, AI can monitor the execution of all your tests and improve the stability and design of your tests. Maintaining a stable and predictable test suite is something that will save you a lot of time.

These AI features are easy to use and will reduce the time and effort of unit testing by more than 50%, from creation to maintenance. It’s easier for you and your team to adopt best practices for unit testing with AI. It allows for a better understanding of test functions for the new developer. Expert testers will appreciate the time savings for creating tests that are meaningful and test the true functionality of the code with valid assertions.

Parasoft Jtest is an automated unit testing solution for active Java development and legacy code that contains these AI features. It leverages open source technologies such as JUnit, Mockito, and PowerMock to fit into most development environments. It’s not a vendor-locked solution, which makes it easy to adopt, integrate and scale.

Want to see Parasoft Jtest in action?

Security Testing in Java

It’s important that your application be as robust as possible, but security is also key to any successful app. Parasoft Jtest integrates security standards into the development process to check compliance with OWASP, CWE, CERT, PCI DSS, and many others. Jtest can apply static tests inside the IDE or on the builds and integration server and find compliance vulnerabilities throughout the development life cycle. The reporting, auditing, and continuous feedback provide a real-time view of compliance status.

Final Thoughts about Java Testing

An automated skeleton test that developers can customize based on the business logic or test scenario that makes recommendations for other tests that are needed will significantly reduce the time to make the tests. It’s important that you achieve correlated coverage of all your testing and know which code you don’t have tests for. You also want to ensure any changes don’t break existing code with regression testing.

Automated testing allows you to conduct testing in hours or days instead of weeks or months. Implementing tools that can help you be more agile may also significantly reduce the time it takes to test. If your team is not getting good test results, write a test plan and incorporate any of the tips in this blog post that you find useful. Go to management or your software team lead with your plan and be the influencer that establishes the best practices that can be implemented throughout the enterprise.

Java testing, whether it be creating JUnit test cases or applying new test annotations for your next Java project, will not only improve the functionality of your development project, it will save valuable time. Perhaps the most significant outcome of software testing is a better overall ROI for your project.

See how you can dramatically reduce your test time to minutes or hours. Download our free ebook for tips and best practices for Java developers.

Make unit testing easier and faster with AI-enhanced Parasoft Jtest.