JUnit Testing Secrets: How To Write Tests That Never Fail
New to automation testing? As you’re getting familiar with the process of creating test scripts, you may come across different testing frameworks, such as JUnit, if you’re using Java. While JUnit is a popular choice for many Java developers, However, it’s important to remember that JUnit is just one option among many available for Java automation testing.
When working with JUnit testing, it’s more than just using a couple of “@Test” annotations. Rigid test cases can lead to frustration. Don’t worry! In this article, we’ll reveal some key best practices and tips to help you write flexible, reliable tests that won’t fail for the wrong reasons.
Why Tests Fail
Before we start understanding how to prevent test failure with JUnit testing, it is very important to understand why your tests are failing in the first place. So, in a traditional environment, tests will fail if there are bugs or regressions within the code base of the application. Let us now go to some of the major unintended reasons that cause the failure of modern testing processes:
- Tests fail because the environment changes like file system differences, network issues, and variations in time zones.
- Your test can also fail intermittently due to concurrency issues or timing differences. This can lead to the testing infrastructure not being able to effectively communicate with the applications that you’re currently testing.
- In certain cases, tests assume that all the required data is already present on the existing interface of the application. However, as we are constantly integrating various dynamic elements in the infrastructure, this scenario is not always true. So, tests will fail if you aren’t configuring these parameters properly.
- Finally, all the modern test cases heavily rely on exact string matches or dependencies. However, you will see that in modern scenarios, all these dependencies change frequently depending on all the application updates. So, if you do not update them accordingly, your test will surely fail.
All the above tests are often referred to as flakey tests. These tests can also give rise to a scenario known as false positives and false negatives. This is a condition when there is an error in the application, but the system reports it to be perfectly working and vice versa.
Effective JUnit Testing Secrets
To help you avoid all the failure scenarios that we have discussed above, let us go through some of the major secrets of JUnit testing that we highly recommend the testers incorporate in a test execution process. You must remember that we have created this list of testing scenarios considering most of the common general use cases that are currently prevalent:
Eliminate Flakiness By Controlling Test Environments
One of the major reasons why tests fail is that they are heavily dependent on the testing environment. For example, if a test relies on the system clock or a particular time zone, there is a high risk that unexpected failures will occur on different machines or at different times. So, the most effective solution to this probability is to completely eliminate the external dependencies or strictly control them as per the requirements.
You can use in-memory databases for applications that need a database. This approach will guarantee the test consistency and also resets between the test runs. It will also remove your dependency on the actual state of production, like databases that can contain records or constraints that are bound to differ.
If you’re working on a rest API call, an external email service, or a payment gateway, various parameters like network lags, rate limits, or intermittent connectivity will affect the testing of these services. So, we recommend the testers mock the dependencies so that the tests can verify the internal logic instead of the external endpoints.
You must use clock obstruction if your code relies on the system time. You can also consider using libraries like Java’s “clock” class. This approach will make your test environment terministic to prevent failures that can occur if a test runs at midnight or close to a time zone boundary.
Finally, you must use Docker for complex disintegrations. This is because containerization will help you replicate a consistent environment every time you are running the testing process. Therefore, you will have an exact idea of how the environment will look in every scenario.
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Use Mocks And Stubs Effectively
If you’re working on a unit test, your main focus should be on the unit that you’re currently testing. This mainly includes a single class or a smaller group of classes that can work together very easily. If you try to focus on other external dependencies, it will introduce complexity and risk of test failure. This is exactly the problem that mocks, stubs, and fakes aim to solve.
- Mocks are nothing but objects that can track interactions like methods called and parameters passed so that you can verify the behavior of all these interactions.
- Stubs, on the other hand, are simplified implementations that return fixed data or behave in a productive way so that you do not face uncertainties in the application testing process due to unpredictable real-world scenarios.
- Finally, fakes are much more complex substitutes that can simulate the behavior of a real component without external side effects. It is like filtering out the required user behavior without going through the frustration of having unwanted and unpredictable dependencies.
All these three test doubles will have a very important role in reducing the test flakiness, improving the test focus, and also speeding up the overall test execution process.
To further help you understand the implementation of these parameters, we have mentioned a sample code snippet that uses Mockito for mocking dependency within the JUnit test:
2. Structure The Tests For Clarity And Maintainability
You must remember that clear and maintainable tests are much less likely to break due to unpredictable reasons. On the other hand, disorganized tests without logic will lead to confusion. So, so these tests are more prone to assumptions and, ultimately, failures.
- The most effective solution to this problem is the implementation of the Arrange-Act-Assert (AAA) pattern. In the arrange segment, you have to set up the data command box and the initial conditions that will be required for the testing process. In Act, you have to execute the method or operation under tests that you’ve previously set up.
- Finally, in the Assert stage, you need to verify that the outcome of the testing processes is as expected and also abide by the brand guidelines. So, you can use this straightforward approach to improve the clarity, as anyone looking at the test will be able to immediately see the test data setup process and the operation that is being executed.
This entire process is ultimately highly useful to ensure the proper validation of the test results and its implementation in the architecture.
One Assertion per Concept
Although it is not practically possible to have one assertion for every test, as there will be thousands of different testing processes in a modern application, try to group your assertions around a single behavior or concept of the application.
This is because if you are working on test cases that check for multiple unrelated outcomes, it can be massively confusing to debug the functioning of it.
Use Descriptive Test Names
It is very important to make the test names obvious so that even the non-technical members of the team can use this name and clearly understand the respective element that the test is created for. For example, use names like shouldThrowExceptionWhenCustomerIdIsNull().
You can also use this approach to debug the failing test, as the names will also show the expected behavior for every allocated testing process. In short, your test names must eliminate any form of guesswork or misunderstandings in the strategy phase.
3. Understand The Importance Of Real Device Testing
It is very important to understand the importance of integrating real device testing with JUnit testing. This is because the functioning of your application will be massively influenced by multiple physical parameters that are just not possible to replicate with just the emulators and simulators.
Some of the most important parameters that you must consider in this include user interaction errors, incompatibility with outdated browser versions, or even a broken device altogether.
So, how do you implement real device testing without going through the nightmare of setting up and maintaining a million-dollar device lab? It is simple! You have to integrate cloud testing platforms like lambdaTest within your testing environment. To shed more light on this segment, let us learn more about this platform:
LambdaTest is an AI-Native test orchestration and execution platform that lets you perform manual and automation testing at scale with over 3000+ real devices, browsers, and OS combinations. The integration of LambdaTest with Selenium WebDriver uses various dedicated browser drivers like the Selenium ChromeDriver to execute automated cross-browser testing.
After running all the testing processes, LambdaTest will automatically display a comprehensive test report that will constitute multiple visual parameters like screenshots and videos. The role of these inclusions is that they will help you easily find the faulty element within the infrastructure of the application and implement the required debugging steps.
Example JUnit Testing Script
Since we have discussed multiple secrets in this article, we have mentioned a sample test script that implements all the secrets to create a highly productive and resilient JavaScript.
In this example, we will have a UserService responsible for creating users in an application. It will also interact with a UserRepository and an EmailService for saving user data and sending a welcome email.
The Bottom Line
Based on all the factors that we have put forward in this article, we can easily say that writing tests that never fail isn’t about being sneaky or avoiding errors; it’s actually about constructing robust, reliable, and meaningful tests that will fail only if there is an actual defect.
By implementing all the secrets that we have discussed in this article, you can massively improve the productivity and the credibility of your testing infrastructure. It will also help you to confidently rely on the test reports to take all the information about the future of the application that you’re working on.
Finally, you must remember that in a real-world environment, the test will fail if the logic is flawed or a new feature is added to the behavior without accounting for it. But, if you are diligent and methodical, these errors will not impact the quality and delivery of your application.
