What is a unit test?
A unit test checks the behavior of a software unit in the system. This test for software checks whether a small and isolated part of the code base, called a“unit“, behaves as the developer intended. Unit testing is an important test procedure when programming software.
Unit test – test procedure for programming
The unit test checks whether an isolated piece of code does what it is supposed to do
Unit tests therefore check the smallest parts or components of an application by comparing their actual behavior with the expected behavior in complete isolation.
Complete isolation during unit tests
For the test procedure, complete isolation means that the developers do not connect the application to external dependencies such as databases, the file system or protocol services such as HTTP during the unit tests.
This means that unit tests can be carried out quickly and stably, as they do not fail due to problems with integration with these external services.
Complete isolation during unit tests
Why should you write unit tests as a developer?
As a rule, developers first write unit tests and then the software code. This approach is referred to as test-driven development and is known as Test Driven Development (TDD).
In test-driven development, the requirements are converted into specific test cases, then the software is improved to pass the new tests. During unit tests, the code can be changed without affecting the functionality of other units or the software as a whole. This makes the developers’ work easier, as the errors are easy to find at this stage, which saves time and money.
In addition, within unit test environments, the individual modules of a product are isolated from each other and have their own area of responsibility. In this scenario, the tests are more reliable as they are carried out in a closed environment. These framework conditions also make the code more reliable. A
release
can therefore be used more quickly as error-free software.
What advantages do unit tests offer?
- Unit tests help to find and rectify errors quickly and easily.
- Unit tests contribute to higher code quality.
- Unit tests contribute to a better application architecture.
- Unit tests serve as documentation.
- The main advantage of unit tests is their perfectly precise test focus.
- a unit test is an iterative source of valuable test feedback
What advantages do unit tests offer?
Unit testing is aimed at testing individual functions
As you always test a single function with the unit testing methodology, each unit test gives you absolutely precise feedback. If a unit test fails, the testers can be sure in the vast majority of cases that the tested function is the problem.
Unit testing is aimed at testing individual functions
Unit testing is fast!
Unit tests are also known for their speed. Because they are quick to perform, these tests are carried out regularly and much more frequently than other testing methodologies, making them a source of almost constant valuable feedback.
Because they are quick to perform, these tests are carried out regularly and much more frequently than other testing methodologies, making them a source of almost constant valuable feedback. Here are some important facts that underline this speed:
- Short execution time: Unit tests only check a small unit of code, which makes their execution extremely fast.
- Immediate feedback: Developers receive immediate feedback on the effects of their code changes.
- Can be automated: They can be automated and integrated as part of the Continuous Integration/Continuous Deployment (CI/CD) process.
- Fewer dependencies: As unit tests run in isolation from other parts of the system, time-consuming configurations and setup processes are eliminated.
- Easy repeatability: Due to their speed, they can be easily repeated to ensure the stability of the code.
- Early error detection: Fast tests lead to early identification of problems, which makes troubleshooting more efficient.
- Scalability: Despite an increasing code base, the execution time of unit tests generally remains low.
These factors contribute to the fact that unit tests are an efficient and fast method for quality assurance in software development.
Best practice for creating unit tests
We provide you with a
design pattern
for unit testing. You can create effective unit tests with this tried-and-tested procedure:
To do this, you should observe the following requirements and framework conditions when creating unit tests:
- The tests should be fast and simple, i.e. the developers must execute the test cases at a higher speed, as this serves the purpose of unit testing. If they are slow, the developers will not execute the test cases as often as they should. The simpler the unit test cases are, the more accurate the test results will be.
- Test cases should not duplicate the implementation logic.
- Test cases should be deterministic, i.e. the defined tests should always show the same behavior as long as the analyzed code is unchanged.
- In order to keep the tests deterministic, quality measures must be taken to ensure that the test cases are executed on real browsers and devices, not on emulators and simulators.
- Without use in real production environments, test results will not be anywhere near deterministic or accurate. Use real, functioning devices for meaningful tests.
- Adopt a standardized, meaningful naming convention for all test cases.
Unit tests: The key to ensuring high software quality
How to successfully test your software development with unit tests:
This is how you should proceed to create your unit test for quality assurance:
Step 1: Understand what is to be tested
- Identify the test objectives: Understand the functionality that the unit test should cover. This could be a method, a class or a small function group.
- Define clear expectations: Make sure you know exactly what should happen when the code executes successfully.
Step 2: Set up the test environment
- Choose a test framework: Decide on a framework such as JUnit (for Java), NUnit (for .NET) or Jest (for JavaScript).
- Set up the test environment: Install the selected framework and configure your development environment accordingly.
Step 3: Write the test
- Create test cases: Write test cases that cover different aspects of functionality, including normal, limit and error cases.
- Use assertions: Use assertions to check the expected behavior of the code.
- Keep tests independent: Make sure that each test can run independently of others.
Step 4: Test execution
- Execute the tests: Start the tests via your development environment or a command line interface.
- Analyze the results: Review the test results to ensure that all tests passed or to understand why some failed.
Step 5: Troubleshooting and optimization
- Fix bugs: If tests fail, identify and fix the underlying problems in the code.
- Optimize the code: Use the findings from the tests to improve and optimize the code.
Step 6: Repeated implementation and integration
- Automate test execution: Integrate the tests into a continuous integration process to execute them automatically whenever code changes.
- Keep the tests up to date: Update the tests regularly to keep up with changes in the code.
Step 7: Documentation and maintenance
- Document the tests: Make sure the tests are well documented to make their purposes and approaches clear to other developers.
- Maintain the tests: Maintain and update the tests over time to ensure their relevance and effectiveness.
By following these steps, you can create effective and reliable unit tests that play an important role in the quality assurance of your software.
