Are you a new software developer struggling to implement efficient JUnit testing? We are here for you! Our blog will help you understand the importance of unit testing and introduce JUnit as one of the most efficient processes for executing unit testing. Finally, we will create a comprehensive outline to write effective unit test cases using JUnit with Java.
We consider unit testing to be the most fundamental aspect of software development. This is because unit testing ensures that every individual component of the source code, such as classes and methods, works as per your expectations. Therefore, testers must master the art of executing efficient unit test cases.
The Importance of Unit Testing
Before we create the strategies for effective unit testing, let us go through some of the most important parameters that justify the importance of executing proper unit test cases in your application development and testing life cycle:
- Unit testing helps you detect the bugs at the earlier stages of the application development cycle. So, this implementation, in turn, helps you improve the code’s overall quality.
- A huge list of unit test cases allows the testers to quickly refactor the test code confidently. This is because they will know that any significant code or error will be quickly identified and resolved before it becomes a serious concern.
- We can consider unit testing as elaborate documentation that explains how the code is supposed to work in any kind of scenario or usage condition.
- The proper implementation of unit testing often forces the developers to consider the application’s design aspect and structure the code accordingly. So, unit testing has an indirect influence on creating better design practices during the deployment of the application.
Introducing JUnit
Before proceeding towards the strategic implementation, let us answer the most generic question: what is JUnit? It is a popular open-source framework for writing and running test cases in Java. JUnit has various annotations to identify test methods and assertions to test the expected results. The testers can easily and natively integrate JUnit with various popular development environments and build tools.
Due to these parameters, JUnit often becomes a popular yet powerful choice for modern Java developers and testers.
While using JUnit, you will have access to annotations to define test methods, assertions to check expected outcomes, Test Runners to execute tests, and parameterized tests to run the same test multiple times with different inputs.
Strategies For Effective Unit Testing With JUnit
Now that we have developed a basic understanding of unit testing and the role of JUnit let us go through some of the major strategies that will help the testers to improve their potential and quality while using JUnit:
- Write Clear and Concise Tests
We recommend that the testers consider test clarity one of their primary goals. A well-written test communicates the purpose and expected outcome. These test cases are also easily understood by the non-technical members of the team, including the business and production teams. While implementing this logic, you must keep the following factors in mind:
- Use descriptive names for test methods to convey what is being tested and under what conditions. This will also help you keep track of the test cases when working on highly complex projects with thousands of test suites.
- We recommend that the testers follow the Arrange-Act-Assert pattern. This approach ensures structuring the test suites using the necessary preconditions and inputs. The testers should also act by invoking the method under test and assert the expected outcomes.
We have mentioned a sample code snippet that gives a better idea about implementing both practices.
- Isolate The Unit Under Test
Another important rule is that the unit test cases should only test the unit it is designed for. Therefore, the tests should not depend on other parts of the system. The testers can implement this isolation using mocking frameworks, including Mockito. Implementing this approach will allow the testers to replace the dependencies with mock objects.
To better understand this approach, we have mentioned a sample code snippet that helps the testers achieve this goal.
- Using Assertions Effectively
As we already discussed in the earlier segments, JUnit has a native library of multiple assertions to verify the expected outcomes of the test suite. However, the testers must choose these associations appropriately depending on the situation to make the tests more readable and informative.
To help you with this information, we have created a list of some of the most important assertions and their designated purpose:
- “assertEquals” helps the testers to check whether two values, either input or output, are equal.
- “assertTrue/assertFalse” verifies a given statement and responds with a true or false as per the functioning of the statement.
- “assertNull/assertNotNull” is used to check if an’s status is null or not.
- “assertThrows” helps determine whether a specific exception is thrown during the test execution process.
Let us now improve our knowledge about the use of assertions by taking an example code snippet that implements them as per their requirements:
- Test Edge Cases And Error Conditions
The testers need to understand that an effective unit test case covers the typical use case and helps verify the functioning of edge cases and error conditions. Implementing this approach ensures that the code handles all possible scenarios gracefully without unwanted errors.
Let us divert our attention toward a code snippet that helps us improve our knowledge about the role of unit testing in this regard:
- Integration With Automation Testing
The testers can integrate JUnit with automation testing suites and frameworks like Selenium and Appium to automatically execute these test suites whenever there is any change in the app’s source code.
The testers can also consider integrating cloud platforms to execute automated unit testing with Selenium Java. One such platform is LambdaTest, an AI-powered test orchestration and execution platform that lets you run manual and automated tests at scale.
With LambdaTest, the testers can execute the unit test cases on more than 3000 combinations of real devices, operating systems, and dedicated browser versions. LambdaTest also supports parallel test execution by integrating Selenium Grid with JUnit.
However, we want to warn the testers that automation testing initially involves a steep investment. This cost mostly covers the expenses of integrating various libraries, dependencies, and tools that are highly important for automation testing. So, you must have a steady revenue cycle and proper returns on investment before migrating to complete test automation.
- Maintain Test Independence
The testers need to ensure that the test scripts are independent. This approach means that the outcome of one test should not affect the outcome of others or even the functioning of other elements within the application infrastructure.
To implement this process, the testers can set up a fresh state before each test and clean up after it is executed, if necessary. The following code snippet will help us to develop a better understanding of the implementation of this process.
- Use Parameterized Tests
The testers can use parameterized test cases to run the same test suite with multiple inputs. The execution of this process helps reduce code duplication and massively improves the overall test coverage while executing unit testing.
The following code snippet will allow the testers to implement a parameterized testing approach while using JUnit:
- Mock External Dependencies
It is a common practice for unit test cases to involve external dependencies like web services or databases. While working with such unit testing suites, you must use mocking frameworks like Mockito to simulate these dependencies. The following code snippet will allow the testers to implement this approach with JUnit:
- Ensure Fast And Repeatable Tests
The basic principle of unit testing is that it should be repeatable and fast. This is because slow unit test cases can hamper the development process. On the other hand, inconsistent test results on subsequent runs can be untrustworthy and frustrating for the testers.
- To ensure the above process, the testers can implement the following strategies in their testing environment:
- It is very important to keep the setup tasks minimal to ensure the fast execution of the unit testing suite.
- The testers should use in-memory databases like H2 to avoid the overhead of interacting with actual databases while working with unit tests that need external databases.
- Finally, it is very important to mock network calls to avoid dependencies on external services and ensure repeatability. This approach will also help you verify the stable performance of your application on multiple network conditions.
- Continuous Integration
We strongly advise the testers to integrate their unit tests into a continuous integration pipeline. This approach will help them ensure the tests run automatically with every code change. This approach also provides immediate feedback on the impact of various external changes and helps the tester detect crucial errors at the earlier stages.
- Code Coverage And Quality Tools
Finally, we advised the testers to use code coverage tools like JaCoCo to measure the extent of code your unit test cases covered. While it is not advisable to aim for 100% test coverage, you must identify untested parts or elements within your application’s source code.
Moreover, you should also use static analysis tools like SonarQube with JUnit testing. This implementation will allow you to enforce coding standards and detect potential issues in the core infrastructure of the application.
The Bottom Line
So, based on all our discussion points, we can safely conclude that JUnit is a powerful tool for unit testing in Java. By following effective testing strategies, the testers can massively enhance the quality and reliability of the Java code. By following all the strategies outlined in this article, you can ensure comprehensive test coverage with JUnit testing.
By integrating the unit test cases into a continuous integration pipeline and using code coverage and quality tools, the testers can also enhance the robustness of the unit testing and streamline the overall application deployment process. Finally, we request the testers to embrace these strategies to create a more maintainable, bug-free, and smoother deployment process.
