10 unit testing best practices

30 maart 2020 om 14:03 by ParTech Media - Post a comment

Every developer writes code to solve a problem, but if you ask them how they know for certain wether or not their code functions properly, you might not get an answer that satisfies your quench for clarity.

Why is this? Because developers still refrain from writing unit tests to test the quality of code. Unit tests are not just tricky to write, but time-consuming to maintain.

But, what is Unit Testing?

In the application development process, unit testing is a testing practice of individual code units to determine they are fit to business requirements. In unit testing, the smallest possible components are tested. A single unit is small, so it is easier to plan, write, test, and analyze unit test results than larger production codes.

Why should developers write Unit Tests?

  1. Because we want our code to work

  2. Because we want it to keep working

  3. Because we want to develop faster with more confidence and fewer regressions

  4. Because we make mistakes

Though, writing unit tests is a tricky process and is tough to maintain, but is achievable. There are proven best-practices for doing unit testing.

10 unit testing best practices

Add the following top unit-testing best practices in your development processes and ensure the desired output from your project development.

1. Adopt a well-organized test practice

Some organizations write unit tests parallel to the production code of the application. The aim is to have test codes before the production code. When you adopt well-organized test practices like mutation testing, test-driven development, or behavior-driven programming, you can review tests and production code together. It further helps you understand the code being written and improve the tests accordingly that gives you confidence in the quality of code being shipped.

The approach helps make your unit testing processes scalable and sustainable.

2. Name your test well

Unit testing is more than ensuring production code works. They are the best documentation to track an application’s behavior. Therefore, you must follow naming standards for each test that explicitly tell the intent of barely reading the names of test cases.

Ideally, you should save your test cases in three parts:

  • Save your test with the strategy being tested
  • Save your test given the name of the environment under which it’s being tested.
  • Save your test with the proposed behavior when the scenario is requested.

The more readable your tests will be, the more it will be easy to fix a bug for not just the one who wrote it, but for other developers working on the project or will work on the project.

3. Write reliable and trustworthy unit tests

A simple yet rewarding practice is to write trustworthy and reliable tests. The trustworthiness of unit testing does not just rely on when test units pass the test, but when the test suite reports you about things that go wrong.

Passing tests should produce no output while falling tests must produce clear output like unambiguous error messages.

4. Make automated unit testing a rule

You may feel automated unit testing the most challenging testing discipline, but it ensures rapid feedback. Automated unit testing is also a less expensive way to find errors and fix them.

Even if you can do automated unit testing on many levels, rapid feedback gives you insights about things that matter most to you like: code coverage, modified code coverage, performance, how many tests are being run, and so on. The insight helps you do in-depth analysis and enable you to work more effectively.

5. Focus on single use-case at a time

Good unit testing practices apply to test a single use-case at a time and validate its behavior against the expected output. Adhering to this simple practice helps understand and maintain code being written, easily.

6. Minimal assertion per test

One requires something more than single use-case tests and good test names to figure out what’s being wrong in the unit tests. And that is the use of logical assertion per test. Your test should contain minimal assertion, i.e., validate only output/side effect of the tested method.

7. Unit test should be isolated

Unit testing follows a standard of testing a single unit.

That means the unit under test needs to be completely isolated from any other unit or dependencies.

A unit should be considered only “testable” when its dependencies can be and are “faked” or “stub” and thus tested, without including its real dependencies or global/external state.

8. Truly unit, not integration

Sometimes, tests that start as unit tests end up as integration tests and make it difficult to isolate issues that occur, calls for more resources to run, and significantly affect the pace of application delivery. Therefore, a unit test and the system under test must abstain from external factors.

9. Aim for 100% code coverage

In unit testing, it is possible to break down into smaller, reusable, and testable components to get 100% coverage. Automated unit testing further helps cover the entire code base. Thus you can expect 100% coverage.

Code coverage is a crucial metric, but be careful and not spend too many efforts for 100% coverage. Even 60% - 80% coverage is a worthy goal to achieve. 100% coverage is not necessary for every scenario. Here comes integration testing that should cover unit testing gaps.

10. Start using headless testing in the cloud

Headless browsers are gaining popularity. Headless browsers or browser less testing do not involve a Graphical User Interface (GUI). In unit testing, adopting this simple practice of using browsers without GUI or UI makes your test much faster since it no longer needs to load the entire UI.

Headless testing takes advantage of lightweight container instances in the cloud that allows you to write tests quickly and avail rapid feedback almost in real-time.


Whether you accept it or not, unit testing simplifies the development and delivery of modern applications. You can start your journey for unit testing by following the tried and tested principles like keeping unit tests reliable, readable, and isolated and then step into newer ones, i.e., headless testing in the cloud.

By adopting the best practices for unit testing as outlined here, you not just enjoy a faster pace of deployment, but highly practical applications.