Defining Unit Tests
Unit tests individual software components, so you can be confident they behave as
you’d expect them to. Since the developer who authored the code has the most
insight into its desired behavior, unit testing typically falls under their jurisdiction.
Unit, end-to-end, and integration tests ensure high-quality code from development.
Unit Testing Advantages
The following are a few advantages of unit testing:
Debugging Simplified: Streamlines the debugging process by allowing you to test
the functionality of individual modules without disrupting the more significant,
integrated program.
Loosely Coupled Code: Loosely coupled code is a coding best practice that Unit
testing achieves by purposely decreasing the interdependencies between units.
Comparatively quicker than functional testing: Due to the compact nature of units,
a battery of unit tests can be executed in a matter of seconds (if automated).
Minimal Regression of Code: All test suites can be rerun after a code refactoring
or extension to check that the changes did not break any pre-existing functionality.
Extensive Code Coverage: Unit testing automation is a great way to improve
code coverage since it allows you to test even the tiniest parts of your program.
Best Practices For Unit Testing
The following recommendations will help improve unit tests.
Create Simple and Readable Tests
Unit testing is essential to guarantee that your code behaves as expected. The only
way to figure out why a unit test fails is to develop straightforward and easy-to-
understand tests. The fewer moving parts in a test, the less effort you’ll need to put
into writing, maintaining, and understanding it. Furthermore, it is simpler to
refactor tests that have fewer moving parts. The tests may fail if they are too
complicated or need code modification.
Ensure Tests You Write Are Deterministic
A deterministic test will always produce the same results if the code is unaltered. As
a result, you can recognize the problem and implement a solution. If you change
the code and rerun the test, you should get new results, one of which will be
successful.
Passing or failing a non-deterministic test without modifying the code is possible. As
a result, it is also known as an unstable test since it complicates efforts to identify
the source of the problem and resolve it. By isolating the example under test, you
remove any potential for it to influence subsequent cases and do non-deterministic
testing.
Test Single Scenarios
Test Single Scenarios using unit test tools; while there are a wide variety of tests
and variables that you can verify, it is essential that each unit test focuses on a
single use case.
If a test fails, it becomes easier to pinpoint the problematic code by limiting
coverage to a single case. However, there are risks involved in using a single test to
target multiple use cases; if the test fails, you’ll need to spend time debugging to
figure out what went wrong.
Automate Your Unit Tests
You should implement a CI/CD pipeline or daily/hourly automated unit testing. Put
in place the proper settings so everyone on the team can access the automated
testing reports. Code coverage, performance, and test iterations are just some KPIs
that benefit from this open dialogue between teams.
Ensure You Write Isolated Tests
To ensure that individual parts work correctly, you must perform unit tests in
isolation. This testing is more stable and faster because you’re just dealing with a
single logic. Test doubles allow you to construct fake versions of an entire class to
use in your experiments in complete isolation.
Ensure You Avoid Test Interdependence
For unit testing, full test coverage is not mandatory. Rather than configuring a large
number of unit tests solely to achieve the required code coverage, it is preferable to
configure a smaller number of high-quality tests. Since unit tests aim to verify
isolated code sections, it is vital to avoid creating dependent tests.
When the results of one unit test are dependent on those of another, we say that
the tests are dependent on one another. When a single test fails, the entire suite is
deemed ineffective. Avoiding test dependency in unit tests is one way to avoid this
problem.
Attempt to Prevent Active API Calls
When testing, it’s common to come across database or API calls that aren’t
necessary. However, if the tests do not activate these calls, they should be
disabled. It is best to supply API stubs containing the essential behavior and
responses to keep tests focused on only the relevant components.
Combine Integration and Unit Tests
A common way to illustrate how you should divide test resources is using a “testing
pyramid.” As you move up the testing pyramid, the tests get more complex and
less reliable. Top-level tests are more complicated to set up and take longer to
execute and debug than their lower-level counterparts. It will help if you put most
of the testing effort into automated unit testing, which corresponds to the testing
pyramid’s base.
Validate all the specifics via unit tests, including edge cases and boundary
conditions. When evaluating an API or app’s overall behavior, use other types of
unit testing tools with caution. Manual testing should only be used for debugging
and final release acceptance and should make up a minimal fraction of your overall
testing pyramid.
If you want to automate and cover much ground in your testing, the Pyramid Model
can help you figure out what to do.
