Key to Successful Unit Testing – How Developers Test Their Own Code?

Black Box evaluators are not concerned with Unit Testing. Their primary aim is to verify the application against its specifications, while ignoring the inner workings of the system.

However, for those who dare to think beyond the conventional, have you ever been curious about how developers test their code? What techniques are employed to scrutinize their code before it’s released? And what is the importance of developer-testing within an agile workflow?

The response to all these queries is Unit Testing. In this post, my goal is to shed light on the importance of Unit Testing, which allows development and testing groups to work more efficiently together in designing, evaluating, and rolling out superior applications.

Who knows, some of you might even transition to white box testing and adopt these methods for code verification and optimization in the future!

Understanding Unit Testing

Unit Testing is far from a new invention. It’s been a part of programming since its infancy. Typically, developers and occasionally white box evaluators formulate Unit tests to improve code quality by checking each portion of code used to fulfill functional specifications (commonly known as test-driven development or test-first development).

Most of us are acquainted with the usual explanation – “Unit Testing is the practice of verifying the smallest testable section of code against its original purpose.” A unit test is considered a failure if the purpose or requirement isn’t fulfilled.

Simply put, it involves generating a section of code (unit test) to inspect the code (unit) made to execute specifications.

Unit Testing’s Role in the SDLC

Developers employ either manual or automated tests for Unit testing to verify that every software component adheres to the client’s requirements. A unit can pertain to an individual function, object, method, procedure, or module within the software being assessed.

Writing unit tests for testing individual elements facilitates the creation of comprehensive tests when all elements are combined. It is generally done as the first phase of testing during software construction.

The Importance of Writing Unit Tests

Unit Testing is utilized to create strong software components that facilitate code upkeep and defect removal. Detecting and resolving faults during the early phases of the software development cycle are crucial. Unit Testing serves this function.

It is a fundamental part of the agile software design process. In a nightly build, the suite of unit tests should be run, with a report then being generated. If any unit tests do not pass, the Quality Assurance (QA) team should decline the build for evaluation.

Implementing this as a standard procedure can lead to many defects being detected early in the development process, which can lead to considerable time savings.

I acknowledge that many developers abhor writing unit tests. Due to tight deadlines or lack of enthusiasm (some even pen empty unit tests to achieve a 100% passing score ;-)), they often neglect them or produce inadequate test cases. It’s vital to craft good unit tests or not write any at all. More crucially, there must be sufficient time and a conducive environment to fully reap the benefits.

Methods of Unit Testing

There are two ways to conduct unit testing:

1. Manual Testing
2. Automated Testing

With Manual Testing, the tester carries out test cases manually without the aid of any automation tool. This method demands manual execution at every stage of the test. Manual Testing can be cumbersome, particularly for repetitive tests that necessitate considerable effort to formulate and execute test cases. A proficiency in any testing tool is not required.

It’s a fact that 100% automation is unattainable, and thus, there will always be a requirement for manual testing.

In contrast, Automated Testing utilizes software testing automation tools to automate tests or test cases. These tools can document and save tests, which can subsequently be replayed as often as needed without further human intervention.

The tools can also input test data into the tested system and compare expected outcomes with actual results, generating reports automatically. However, the initial investment for test automation tools can be steep.

Techniques Utilized in Unit Testing

#1) White Box Testing:

In white box testing, the tester has an understanding of the software’s internal structure, including the code, enabling them to test against the design and specifications. Hence, white box testing is frequently referred to as transparent testing.

#2) Black Box Testing:

In black box testing, the tester has no knowledge of the software’s internal structure and code.

#3) Grey Box Testing:

Also referred to as semi-transparent technique testing, this form of testing involves testers having only limited knowledge about the internal structure, functions, designs, and requirements.

Actual input from the front-end is used in debugging to obtain accurate data from the back-end. Grey box testing is considered a blend of black box and white box testing procedures.

The following types of testing are encompassed in Grey box testing:

• Matrix Testing.
• Pattern Testing.
• Orthogonal Pattern Testing.
• Regression Testing.

The Advantages of Unit Testing

1. Increased agility of the process: When incorporating new functionalities or features into existing software, altering previously scrutinized code can prove risky and expensive.
2. Enhancement of code quality: Unit Testing inherently improves code quality. Bugs discovered during this testing phase are corrected prior to integration testing, resulting in a solid design and development, as developers write test cases based on an in-depth understanding of the requirements.
3. Early identification of bugs: By conducting unit tests, developers spot bugs early in the software development lifecycle and resolve them. This includes aberrations or omissions in the requirements as well as bugs in the developers’ implementation.
4. Smoother changes and straightforward integrations: Unit testing allows developers to restructure code, make modifications, and maintain it without difficulty. It also simplifies code testing after integration. Rectifying an issue during Unit Testing can alleviate many other problems that might crop up during later development and testing phases.
5. Access to documentation: Developers referencing the functionality at a later stage can easily refer to unit testing documentation, making it easier to implement corrections or work efficiently.
6. Smoother debugging process: Unit testing simplifies the debugging process. If a test fails at any point, the code needs to be debugged, but the process can proceed smoothly if there are no failures.
7. Reduced expenses: Identifying and resolving bugs during unit testing decreases costs and shortens the development timeline. If the same bugs are discovered later in the development lifecycle, after code integration, tracing and resolution become more complex, making it more costly and prolonging the development period.
8. Demonstration of code-coverage through unit tests: This is especially advantageous in the agile process. Testers do not obtain functional builds for testing until integration is completed. Simply claiming to have written and checked the code cannot demonstrate code completion. However, running unit tests can verify code completeness.
9. Acceleration of development time: Although completing the code may take longer, having fewer bugs during System and Acceptance testing can speed up development time overall.
10. Code coverage can be assessed.

Life Cycle of Unit Testing

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Attributes of a Quality Unit Test

While I may not be the most qualified person to elucidate what a good Unit Test entails, based on my experiences in various projects, I can describe its characteristics. Poor Unit Tests add no value to a project; in fact, they significantly inflate project expenses by generating and managing unproductive Unit Tests.

How can you formulate effective Unit Tests?

• Unit tests should aim to examine a single unit of code, rather than evaluating integration.
• Develop small and segregated Unit tests with clear names for ease of writing and maintaining.
• If the tests are isolated and tailored for specific units of code, ensure that modifying one portion of the software doesn’t impact the Unit test.
• Unit tests ought to run swiftly.
• Design Unit tests with reusability in mind.

Frameworks for Unit Testing

Unit Testing frameworks are widely used to expedite and simplify the process of crafting Unit tests. Most programming languages do not have built-in support for unit testing. Third-party open-source and commercial tools can create a pleasant Unit Testing experience.

Here is a list of well-liked Unit Testing tools for diverse programming languages:

1. Java framework – JUnit
2. PHP framework – PHPUnit
3. C++ frameworks – UnitTest++ and Google C++
4. .NET framework – NUnit
5. Python framework – py.test

Misconceptions and Facts

• Writing code with Unit test cases is time-consuming and we can’t afford that – The truth is that it streamlines the development process in the long run.
• Unit testing will expose all bugs – It won’t, since the objective of Unit tests isn’t finding bugs, but rather producing robust software elements that contain fewer faults in later SDLC stages.
• 100% code coverage equates to 100% test coverage – This does not assure that the code is free of errors.

Embracing Unit Testing: How?

Successful unit testing can be realized through three fundamental steps.

1. Author unit test code.
2. Run unit test code to check if it fulfills system requirements.
3. Operate software code to look for any defects and verify if it adheres to system requirements.

If, after these three stages, the code appears correct, the unit test is deemed a success. If it fails to meet system requirements, the test is classified as a failure. In such cases, the developer must review and rectify the code.

In some scenarios, segmenting the code for more precise testing may be necessary.

Best Practices

To generate optimal code during Unit testing, consider the following:

• Robust code: If the code is faulty, there might be instances where the test fails, or worse, fails to execute entirely.
• Clear and logical: The code should be straightforward to understand. This makes it easier for developers to write and for colleagues who subsequently work with the code to debug.
• Single test case: It is best practice to write code for just one case, rather than conflating multiple cases into one complex test. By isolating individual cases, the code becomes simpler to comprehend and debug.
• Enable automated testing: Developers should ensure that tests run automatically, ideally as part of a continuous delivery or integration procedure.

Other aspects to bear in mind include:

• Instead of developing test cases for every scenario, concentrate on tests that influence system behavior.
• Cache issues might lead to the recurrence of bugs.
• Ensure that test cases are not dependent on each other.
• Be mindful of loop conditions.
• Plan test cases more often.

Final Thoughts

Unit testing is necessary when there’s a requirement to scrutinize each function separately. Identifying and fixing bugs during this