From a developer’s perspective, Android has gone a long way since its early days. There was a time when it was customary to write all of the codes, from UI things to low-level networking calls and inside Activities. The Android development process has developed a lot since then. Aside from the apparent benefits, this development did a fantastic job raising the quality of an ordinary program, and Unit Testing is one of the key components that enabled this. When we break application logic into discrete components (like view models, repositories, and use cases), more and more engineers focus on covering every element of the code with a reasonable level of automation. Automated unit testing allows us to do more unit testing in less time while maintaining accuracy(and standard).

Levels of Unit Testing

levels of testing

Any build may generally go through four steps of testing

They are:

  1. Unit testing,
  2. Integration testing,
  3. System testing, and
  4. Acceptance testing

Unit Testing is the first testing level, covering every small functionality of your product. It tests the behavior of a single component of software that is not reliant on other parts.

Role of Unit Testing

  • In SDLC, it provides early, quick, and ongoing feedback.
  • With its razor-sharp focus, they provide ultra-precise input.
  • Before deploying the product, ensures that quality criteria are satisfied.
  • Software engineers created this to test how units perform when entirely isolated. For isolated testing, developers utilize test duplicates like stubs, mock objects, and so on to replace missing portions in a test module.
  • It allows for continuous testing of in-app modules without dealing with external services or dependencies.
  • Overall, it offers developers a dependable engineering environment where efficiency, productivity, and code quality get priority.

Since unit testing does not examine whether distinct units interact (as they should) with one another or dependencies, a combination with an optimal mix of other tests assures the software’s quality.

Parts of Unit Testing

Unit testing is classified into three sections:


A tiny section of an application that needs testing is initialized. The application is referred to as SUT (System Under Test).


Following startup, a stimulus is applied to the application that needs to be tested. It is commonly done by executing a method that contains the code for testing the SUT’s functioning.


The outcome arrives after the stimulus is applied to the SUT. The actual product is, then, compared to the predicted result. If it succeeds, the feature is operating perfectly; otherwise, you must identify the fault in the system under test.

Unit tests are fantastic! They aid in regression testing and code quality checks. However, they get removed frequently to accelerate the SDLC. However, the price has proven to be prohibitively expensive.

Let’s glimpse some excellent Unit Testing practices to assist you with the process.

11 Best Practices for Unit Testing

Unit testing is necessary for maintaining good code hygiene, and most of us would like to do it more frequently. However, building unit tests are habitually placed on the back burner when something more pressing (or fascinating) comes along. It may also be onerous to create a test suite from the beginning for a legacy codebase that lacks one, and it may not be easy to know where to begin.

Whatever state your code is in, here is a list of approaches you can take to get started developing unit tests for every sort of application.

1. Begin writing exams as soon as possible

Keeping up with the creation of unit tests for a big existing codebase with little coverage is nearly hard to perform manually. That is why, before writing the code on each new project, one should shift-left testing and prepare to integrate the unit tests. Test-driven development involves writing tests before writing any code (TDD). TDD keeps your workspace tidy and assists you in writing lean code that performs as intended. It also helped write robust and accurate tests—tests that fail only when the code is broken—so you prevent alert fatigue from too many false alarms and don’t miss failure. Embracing TDD can be time-consuming, but even employing TDD concepts as a starting point will result in higher-quality code.

2. Tests should be separated and isolated

The test cases should be different. Test cases can be organized the way the developer wants. The cluster is defined as short or long-running test cases. The test should be orthogonal and independent of the other test cases. If this were not the case, every change in the behavior of a single test case would affect several tests. It is possible if superfluous assertions are not used unnecessarily. The reports should correspond to an application’s unique behavior. They should be separated and run in isolation, without relying on other external elements. The example examines the addition of a zero to a number. The test phase should not include claims about multiplication functionality.

3. The test must be High-Speed

Developers create unit tests conducted repeatedly to guarantee that the program is free from defects. If these tests are sluggish, it will add time to the execution of the test cases. One slow test affects the performance of the entire suite of unit test cases. Hence, developers must employ excellent coding principles to reduce execution time significantly. The unit test is a terrible piece of test code. Execution will be sluggish since we are not leveraging the stream notion, which exponentially boosts the execution speed of the code. Using streams in unit test code is a best practice since it accelerates the execution.

4. Readability of unit testing

A unit test should be legible and easy to understand. Learning about the unit test’s functionality is an essential part of testing. It should clearly explain “the scenario” it is trying, and if the test fails, they should understand why it did. The tester must solve the problems quickly. Test cases should not be overly complicated and should be carefully designed to improve test readability. Every variable and test case should have a meaningful name. This name should be descriptive of the activity or function under evaluation. Terms that are chosen should neither be too short nor too long. Variable or a test cannot have a name like “Show Logical Exception.” This name has no connotation associated with it.

5. Automated Unit Testing

Automation proves very beneficial when working with hundreds of tests in your suite and integrating them across applications. Using CI/CD technologies and selecting a solid unit testing framework will help uncover any issues as early in the SDLC as possible when they are the easiest and least expensive to fix.

Though automated unit testing may appear difficult; however, it undoubtedly provides faster feedback, more test coverage, and improved performance(at the least). In summary, it aids in thorough testing and produces better findings.

6. Excellent test design

Treating the tests as carefully as the production tests. Applying good design techniques is necessary when creating the testing framework. For instance, there should be little connection between test and production code. To improve test efficiency, one should delete dead code. You must be able to manage your memory and your time efficiently. A good code base will make refactoring and maintenance much easier in the long run. If one has a lousy suit, it will make their life more difficult to discover that their code is not adaptable to change.

7. Maintain your tests as you would your production code

Unit tests, like the preceding point, also code. Unit testing is evergreen and can be one of the best types of documentation if you refactor them as you refactor your production code. One poor behavior is that after refactoring the code and assuring to repair the difficulties later but it never happens.

8. Make them simple to maintain

Unit tests should be simple to comprehend and should notify one (or the person in charge of maintaining your code) precisely what’s wrong at a look. Choosing a clear, descriptive name for the unit tests ensures that they are easily legible in the future for all. One should add comments that clarify the logic and messages that make assumptions explicit things as much as possible.

9. Adopt a well-organized testing procedure

Test codes should be generated before production code in a well-organized scenario to assess the tests alongside software development. Being properly organized is a blessing, and it is also true for unit testing. When software development and testing are coordinated, the quality of the product is greatly improved.

Test coding responses include test-driven development, mutation testing, and behavior-driven programming. It also aids in better comprehension of the code and hence in the improvement of test code.

10. Deterministic tests should be written

Deterministic tests either pass or fail all the time until rectified.

However, until the code is modified, they behave the same way every time they are executed. So, a flaky test, a non-deterministic test that passes and fails at random, is equivalent to having no difficulty.

For example, suppose you wrote a unit test for the method to calculate interest, and it passed.

It should continue to pass until modifications to calculate interest are implemented.

It should fail every time, no matter how many times it is run, until the fault with calculated interest is addressed.

If the test is untrustworthy, developers disregard it since there is no definitive evidence of a flaw in the code or any obvious outcome.

To avoid non-deterministic tests, one must ensure they are isolated from other test cases. Controlling external dependencies and ambient data like the machine’s current time and language settings might help you address flaky tests.

11. Periodically update the tests

Unit tests are excellent for long-term projects because they provide extensive documentation to new team members, making the code and its attributes easier to comprehend. So, maintaining and updating the tests at regular intervals makes them perfect test suites for developing helpful documentation. Unit tests lacking this attribute are less valuable since they slow down the team’s work progress.


The recommended practices above aren’t the only strategies to improve your results; they will undoubtedly make your unit testing process more accessible.

Some sophisticated features are present that must be hand-coded due to certain constraints. Unit testing, for example, is specialized and distinct, and its results fail compared to the other types of testing.

Instead, accepting its continual learning process and practicing helps one achieve mastery.