Unit Testing

Considered low-level quality assurance, unit testing is a tiny yet powerful way of exercising your code to determine whether it is fit to be used. This stage of quality assurance focuses on a small piece of an application, even something as granular as a line of code like a method or class, and asks in a very literal sense, “does this code do what I expect it to do?”.

A unit test details absolute requirements for an isolated piece of code, essentially outlining what output should be expected as a result of a specific set of inputs under certain conditions. Then it forces the code to complete an action and verifies the results, generating valuable insights about the code’s functionality and design.

A helpful analogy for software quality assurance is a hot air balloon. Before you gauge how well a hot air balloon flies as one giant apparatus or even how well all of its various elements work together, you’ll want to “unit test” every single part involved in its production. Does each piece of wicker that is woven to create the basket pass a check for flexibility, strength, and weight? Do all the mechanical parts of the inflator fan that fills the balloon with air work correctly? Down to each stitch of the nylon or canvas envelope (balloon), unit quality assurance confirms the functionality of each component.

Unit Testing

Advantages of Unit Testing

The importance of unit testing in software development is often overlooked because it does require an initial investment of time; however, it offers critical assurance in the code allowing developers to catch bugs early on in the development stage and any time there is a change made. Software unit testing:

Advantages Unit Testing
  • check

    Lays a foundation for creating a sustainable, internal application structure by validating the accuracy of each integral part.

  • check

    Simplifies the debugging process. Locating and repairing a defect revealed by net unit testing is much easier than addressing defects when a test fails at a higher system level.

  • check

    Accelerates productivity by streamlining development and lowering the risk of time-consuming and costly bugs down the line.

  • check

    Improves the programming design by encouraging developers to write in a testable way that more clearly highlights design flaws when they appear.

  • check

    Builds consistency and confidence in the application building blocks themselves as well as across the team of engineers who wrote it.

Checklist for Executing Unit Tests

Depending on the development methodology, a software developer will employ unit testing either before or after writing the actual code that will be tested. These often early-stage tests are typically written in the same programming language as the application’s source code itself, be it JavaScript, PHP, etc.

Some engineers will do the QA planning prior to writing the code itself because it helps them more thoughtfully define exactly what the code should do. Additional checklist items for producing high-quality unit tests include asking am I checking the smallest module possible? Is my test readable, direct, and easy to maintain? Are my methods and variable names explicit?

With developer unit testing, a checklist may include the following:

  • Line of Code

    Write a line of code

  • Write a Method

    Write a method to test that code

  • Implement the Code

    Implement the code

  • Launch Test

    Launch test

  • Verify Results

    Verify results

What Type of Software Needs Unit Testing?

While validating individual units is typically most effective for larger software solutions, all variations of software can truly benefit from this type of quality assurance. Unit testing for web applications, iPhone or Android mobile apps, digital asset management systems, web portals, and so on can provide quick feedback regarding the cohesiveness and quality of your code.

Developers often conduct this type of evaluation during the code creation itself, however, a large piece of legacy software that lacks these fundamental building blocks can also be aided by retroactive unit testing. For example, the independent software quality assurance specialists at Spiral QA can implement unit testing software tools or create automated unit testing for an entire code base after the fact.

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