Unit Testing Best Practices

Unit testing allows you to test individual code units to make sure they do what the software is supposed to do. Unit testing helps to make sure that code is safe, reliable, and good quality. These are tools that quickly create and automatically create test cases to make sure the code is good on different types of computers, like real ones, virtual ones, and hardware ones.

Unit testing holds significant significance in embedded development environments that necessitate the seamless integration of software systems and hardware, while adhering to stringent functional safety guidelines.

1. Write tests for a number of scenarios

When composing a test case, it is imperative to ensure that all feasible scenarios are taken into account.

2. Write good test names

The intent of the test case should be expressed in a good unit test name. It is imperative to adhere to consistent naming conventions and utilize shorthand only when it is easily comprehended by a reader. Writing good test names makes code easier to understand, which will make it easier for you and others to add more tests in the future.


3. Set up automated tests

Invest in automated unit testing with the aid of a framework for unit testing. An even more advantageous approach is to automate tests within your continuous integration (CI/CD) pipeline.

We can also test manually, where we manually run test cases and get their results. As you can imagine, manually testing small units is extremely tedious. It’s also less reliable. Automated tests are certainly the best approach.

Also, read What is Automated approach to perform Unit Testing?

4. Write deterministic tests

Software testing is full of false positives and negatives, and we need to be careful to avoid them. Consistency in outcomes for tests is the objective to demonstrate the desired function. Therefore, unit tests should be based on certain outcomes. To put it differently, as long as the test code remains unchanged, a deterministic test should exhibit consistent behavior on every execution.


5. Arrange, Act, and Assert (AAA)

The AAA protocol is a good way to organize unit tests. As a good way to test a unit, it makes your test easier to understand by making it follow a logical pattern. The AAA protocol is sometimes called the “Given, When, and Then” protocol.

In order to structure your unit tests, you can use the AAA protocol with the following steps:

  • Arrange: Arrange the setup and initialization for the test
  • Act: Act on the unit for the given test
  • Assert: Assert or verify the outcome

This code shows how to test the add_2_number  function in Python using the AAA structure.

def  add_2_number(a,b):

     return a + b

def test_add_2_number():
  # Arrange
  num1 = 2
  num2 = 3
  # Act
  answer = add_2_number(num1,num2)
  # Assert
  assert answer == 5

6. Write tests before or during development

Test-driven development (TDD) is a method for developing software in which we enhance our test scenarios and code simultaneously. Unlike a typical development methodology, TDD involves writing test code before production code. The Test-Driven Development methodology offers numerous advantages, including the enhancement of the code coverage of unit tests.

The process of TDD is described below.

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  • A unit test should be developed for a desired feature.
  • Write the shortest code you can to pass the new test.
  • When the test is successful, change your code to make it easier to understand and maintain.
  • This process can be repeated if another feature is needed

7. One use case per unit test

Each test should focus on one situation and make sure the results match what was expected for that method. If you only test one thing, you can see the problem more clearly if it fails. This is better than testing for many things at once.

8. Avoid logic in tests

To minimize the probability of bugs, it is recommended that your test code contains minimal logical conditions or manual string concatenations.

9. Reduce test dependencies

It is important that tests be independent of each other. By reducing the number of units that depend on each other, test runners can run tests on different pieces of code at once. The test code can only be considered testable if its dependencies are staged within the test code. The test should not have any real-world or external dependencies that might affect the outcome.

10. Aim for maximum test coverage

Although it is feasible to aim for a 100% test coverage, it may not always be feasible or desirable. Such extensive testing may have budget and time requirements beyond our capabilities. In certain instances, the implementation of comprehensive testing may be theoretically unfeasible (i.e. uncertain).

11. Keep proper test documentation

Keeping a test log will benefit both programmers and, in some cases, end users (for instance, if you have an API)

The testing documentation must meet the following criteria:

  • Reviewable: Any test conducted by a given resource can be examined by others.
  • Repeatable: A test is documented in a manner that permits its repetition on multiple occasions. Repeating the same test lets us check if a bug has been fixed in a new piece of code.
  • Archivable: You can archive tests and related bugs in the documentation, which will serve as a valuable resource for future extensions.

Wrapping up and next steps

Regardless of your current stage in your coding journey, mastering the art of unit testing will guarantee that you can effectively assess the balances in the applications that you create.

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