writing unit test cases

Best Practices for writing unit test cases

A software developer or not, we all know that testing is an important step in the final delivery of software. Without appropriate testing, any software will be vulnerable to bugs and glitches. Such gaps can often lead to poor performance. Therefore, software testing is a business imperative today and not just a means to ensure sound performance. While most people believe that testing is the job of professional software testers at the end of the development cycle, seldom do people realize that it is an ongoing process. In fact, testing at multiple stages has become a norm today with great emphasis on writing unit tests.

What is Unit Testing?

Unit testing, to put it simply, is one of the first steps in software testing. As the name suggests, it is testing individual units for any bugs or performance errors. Units are generally the smallest components of software development. The intention of writing unit tests is to check and identify glitches during the course of development. Unit tests come in handy to make changes and corrections at younger stages of software development when it is easy to do so. As the number of inputs increase, testing becomes more tedious and naturally expensive. While unit testing is important in finding bugs, using it to develop robust software is a better idea. Therefore, writing unit test cases is a wise move during software development.

Why writing unit test cases important?

If you haven’t tried your hand at unit testing, you might feel that it is a waste of time to test every software component. However, if you look closely, you will realize that it is one of the smartest approaches to ensuring bug-free software.

Firstly, if you check your code at the unit level, you put in very less time as there are generally minimal inputs and a single output. Secondly, unit testing is generally automated. Even when manual, any developer can easily perform it. A professional software tester is seldom necessary which significantly brings down the cost. Writing unit test cases is also important to preserve the functionality of the previous code with every additional component. Unit testing at regular intervals can easily decipher which component is causing the glitch and alterations can be made. Finally, testing your software at every step to identify what works and what does not helps you document certain practices that can come in handy.

Characteristics of a good unit test

While we acknowledge that writing unit test cases is a wise move, however, unless your unit test cases are efficiently designed, you may not benefit from it.

  • Independence

The first element to keep in mind while writing a unit test case is to ensure their independence. Since unit tests are performed on individual components, they should not have external dependencies. This simply means that one particular test for a specific piece of code should be independent of any other variable. It should not rely on preceding or succeeding tests to give the desired output. This is important to ensure that the robustness of each component can be judged independently.

  • Simplicity

Unit tests should be short and simple. They should not be too complex or carry technical jargons that are beyond anyone’s understanding. Since most unit tests are carried out by the developers themselves, there is no need to go into complex technical testing like professional testers. Simplicity in writing unit tests makes it possible for everyone to understand their objective and need. Therefore, keeping your unit tests short and simple can prevent serious confusions that may arise due to unnecessary complications.

  • Automation and Speed

While unit testing can be manual in a few cases, automation unit testing is the most effective these days. As unit tests are for the smallest software components, they seldom require human interference. Automated tests can themselves identify if a particular code is producing an aberration. From automation arises the characteristic of unit tests to be fast and almost instantaneous. Software development encompasses testing of a plethora of components and unless the testing is fast, it will become inefficient. This means that one of the most important practices of writing unit test cases is to ensure that the test takes very little time.

  • Document everything

As you must be aware by now that unit testing is a repetitive process and takes place at every level. Remembering what test you used at one particular time is almost impossible. Therefore, one of the best practices to engage in while writing unit test cases is to document them as you go on. Documentation can be a very helpful tool to explore what tests work for what codes for future software development.

  • Uniformity and Stability

When it comes to the characteristics of a good unit test, uniformity and stability are definitely in the race. This simply means that a test must be consistent in its performance. Uniformity and stability are important indicators of a test’s capacity to yield the same results in multiple attempts. In case a test gives different results when applied to a unit code more than once, its reliability is compromised. When the code remains the same, so should the results. Therefore, writing unit test cases that can produce consistent results over a duration of time is certainly a good practice.

  • Code writing vs Test writing

A number of best practices for writing unit test cases are dependent on the software components as well. Firstly, there is no standing rule which says that a particular code can have only a single test. In fact, it is a good practice to check one’s code using multiple unit tests. This can be very helpful in ensuring the robustness of the code along with all aspects. Secondly, it is important to ensure that the time it takes to build a test must be in consonance with the time it takes to build the code. Spending a lot of time on building a testing for a code that took very less time to prepare is simply time wastage. Since unit test cases are but one step in the testing process, spending too much time on them leads to inefficiency and poor time management.

  • Descriptive

One of the final best practices for writing unit test cases is to ensure that their documentation is descriptive. While we have established the importance of documentation, its content is equally important. You must ensure that the test you document has enough content. This suggests that the documentation must take a note of the objective of the unit test as well as the expected outcome. Additionally, it should contain the results of the test including the realized outcome as well as any other observations. Finally, there should be a small description of the nature of the code and the test performed. While none of the descriptions should be verbose, it should be to the point and informative.

In a nutshell, it is clear that if one follows the best practices of writing unit test cases, he/she can go a long way as a software developer. While not all practices will be universally suitable, each one of them carries an immense potential to ensure the robustness of your software.


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