Unit Testing is a way of testing done to the smallest possible module of a program to ensure that it is fit to use. A unit in the form of a code section is tested to see if it can be used in conjunction with other parts of the code (e.g., functions, methods, and variables).
Unit testing is the process of testing individual blocks or units in isolation with the sole objective of unit testing to isolate the written code to test and see if the unit works as intended.
The vital purpose of unit testing is to provide a test suite for a single unit or component of the software, such as a function. The tests typically consist of a series of standard consistency tests for each component written(preferably) by the developer who has worked or is close to the project.
A unit is the smallest testable portion of computer software. In order to assist the process, developers use tools like Unit testing frameworks, drivers, stubs, mock/ fake objects.
If a unit test fails, it is considered either an error or a modified code in the test itself.
Levels of Testing :
The unit testing is obviously the first test to be done, and then all the modules or blocks are to be integrated, and then integration testing is to be carried out. A developer should carry out system testing to evaluate the system’s compliance and functionality requirements in a completely integrated system. And then finally, acceptance testing verifies whether the program meets the specifications and contracts by the client. That is how a developer gets a perfect code.
Why is Unit Testing Important?
Faster and a more efficient way of testing:
Unit testing is the process of writing code, testing it, and then performing the other tests automatically. It is a faster way to test program logic, as performing unit tests takes less time than manual tests or integrated tests conducted by the QA team.
A collection of standardization tests ensures that future changes do not degrade quality. One or more-unit tests document the expected behavior of the unit code and its implementation. To discipline their unit -test development – programmers should introduce a series of tests for units.
Makes the code manageable and more comfortable to edit:
The ability to write unit tests makes it imperative to design systems with high cohesion, and the best unit tests will come from developers very close to the project. Code can be impossible or difficult to test if it is poorly written, forcing developers to structure the functions and objects better. Unit tests make the system more manageable.
More natural to pinpoint the problem:
Another essential purpose of unit testing is to provide insights into the impact of changes in the development process, such as changes to the user interface or the implementation of new features. Based on the failure of test cases, the Unit Test Framework also helps to stop related tests.
Advantages of Unit Testing :
- Even the most experienced developers agree that it is a good idea to practice unit testing. Unit Testing allows programmers to recalculate the code at a later point in time and make the module work.
- One of the most significant advantages of unit testing is that the developer can use testing tools and frameworks.
- Unit testing makes it safer and more comfortable to refresh code because it introduces tests that ensure that refactoring runs smoothly or without interruptions.
- Unit testing also leads to software that is easier to maintain throughout the software life cycle and less prone to errors when new features or updates are added.
- Unit testing provides a clear and concise description of a product or service’s design and specifications in the form of execution. By using unit tests for design specifications, we have a better understanding of what to check implementation and what to use for testing.
- Unit tests take a disproportionate amount of time compared to the code tested. For example, if the cost of writing a unit test is 2 minutes, but the cost of running it is virtually zero, or the price of manually testing the code is 1 minute, then break the break-even point if the developer runs the test twice. Using unit tests instead of manual inspections of the entire code base means that the developer reduces the project’s overall cost.
- A poorly written code can be impossible or difficult to unit test, and therefore unit testing can force developers to structure functions and objects better. Unit testing makes a code as perfect as it can be. The developer first writes the unit test, observes it fail, then writes a second test to pass it, and the cycle repeats until the intended functionality is delivered.
Disadvantages of Unit Testing :
- The Unit Testing’s major drawback is that it is not possible to check all execution paths and that it cannot absorb any significant system errors or integration errors.
- Writing unit tests can be difficult, and the process can be time-consuming.
- Human errors in unit tests could impact the whole system.
- It is not full proof, as said by many; when modules are integrated, there can be new bugs that are undetected by unit testing.
Unit Testing Techniques :
- Black Box Technique: Black Box Technique is a method of unit testing where the SUT(software under test) is the functionality of an application without peering into the implementation, internal structure, or code. The black box technique focuses on Input and output rather than the internal code or knowledge.
- White Box Technique: In White Box Technique, the tester is aware of the internals of the code, structure in this method, the internal structure, and the code’s work, not functionality. Preferably, the tester should have excellent programming skills as the module’s internal perspective, and programming skills are put to the test.
- Grey Box Technique: Grey Box Technique has partial knowledge of the code. This test refines improper code structure or improper functioning usage of an application. It is a mixture of both black and white-box techniques. It is a powerful way of testing a unit.
Unit Testing Tools :
- Nunit : One of the families of the xunit family, Nunit is an open-source unit testing designed for .NET and Mono framework it is the most used tool for writing unit test casing.
- Jmockit: JMockit is another open-source software library. It includes APIs for mocking, faking, and integration testing, and a code coverage tool. The library is to be used together with a testing framework such as JUnit or Nunit.
- Junit: Just like Nunit, it is an open-source unit testing but designed for Java. It is also from the family of Xunit. Used for developers to write repeatable tests, It has a strong foundation for unit testing.
- Typemock: TypeMock can mock almost anything via interfaces. Moreover, it is possible to mock static methods and classes that a standard opensource tool cannot mock. The patterns of arranging, acting, affirming, and testing are implemented, and insulators are made of them.
- Embunit: The Embedded Unit Test Framework Embunit is a new framework for embedded systems. It is designed as a test framework for software applications written in C / C + + and supports all network languages. This framework serves the same purpose as JUnit in Java, but with a different goal: to serve as an open-source, cross-platform testing framework.
Unit Testing Tips :
- If a unit test fails, consider whether it is a bug or a modified code in the test itself. Improving the acceptance test is vital if the developer finds a fault during an acceptance test, but most defects should be detected through equipment tests.
- A beginner to unit testing should look for anti-patterns and eliminate them, and this will make the code efficient and reusable.
- Write smartly; as a minimum, as possible, a code that focuses on the system’s behavior is the perfect code.
- Use mock or false objects for efficient testing. Using the actual system is risky as it puts the data in jeopardy.
- Do not test UI components unless the snapshot tests.