Unit Testing Tutorial for Beginners: Concepts, Types & Tools

What is the definition of unit testing?

Unit Testing is a sort of software testing that examines individual software units or components. The goal is to ensure that each unit of software code works as intended. Unit testing is carried out by developers throughout the development (coding) phase of an application. Unit tests are used to isolate a part of code and ensure that it is accurate. A singular function, method, process, module, or object might be considered a unit.

Unit Testing is a sort of software testing that examines individual software units or components. The goal is to ensure that each unit of software code works as intended. Unit testing is carried out by developers throughout the development (coding) phase of an application. Unit tests are used to isolate a part of code and ensure that it is accurate. A singular function, method, process, module, or object might be considered a unit.

This guide will teach you how to −

• What is the purpose of unit testing?

• Unit Testing: What You Need to Know

• Techniques for Unit Testing

• Tools for Unit Testing

• Unit Testing & Test-Driven Development (TDD)

• The Myth of Unit Testing

• The Benefits of Unit Testing

• Disadvantages of Unit Testing

• Best Unit Testing Practices

What is the purpose of unit testing?

Because software developers often want to save time by conducting limited unit testing, this is a misconception because insufficient unit testing leads to large costs in defect correction during System Testing, Integration Testing, and even Beta Testing after the program has been constructed. It saves time and money in the long run if thorough unit testing is done early in the development process.

The following are the primary reasons for doing unit testing in software development −

• Unit tests save time and money by catching flaws early in the development cycle

• It aids developers in comprehending the testing code base and allows them to make rapid adjustments.

• Unit tests that are well-written serve as project documentation.

• Code reuse is aided by unit testing. Both your code and your tests should be migrated to your new project. Adjust the code till the tests pass.

Unit Testing: What You Need to Know

Developers create a portion of code to test a particular function in a software application as part of Unit Testing. Developers may also isolate this function to test it more thoroughly, revealing any superfluous dependencies between the function being tested and other units, which can then be removed. UnitTest is a framework that developers use to create automated test cases for unit testing.

There are two forms of unit testing.

• Manual
• Automated

Unit testing is often automated, although it may also be done manually. Although there is no preference in software engineering for one over the other, automation is favored. A step-by-step instructional paper may be used in a manual method to unit testing.

According to the automated method,

• A developer creates a chunk of code in the program only for the purpose of testing the function. When the program is deployed, they will comment out and eventually delete the test code.

• A developer might potentially isolate the function in order to thoroughly test it. This is a more extensive unit testing method that entails copying and pasting code into its own testing environment rather than the natural one. Isolating the code aids in the discovery of unneeded dependencies between the code under test and other units or data spaces in the product. These reliances may then be removed.

• To create automated test cases, most programmers utilize the UnitTest Framework. The developer uses an automation framework to incorporate criteria into the test to ensure that the code is accurate. The framework records failed test cases as they are being executed. Many frameworks will also automatically highlight and report these failed test cases in a summary format. The framework may suspend future testing depending on the severity of a failure.

• The Unit Testing process is as follows: 1) Create Test Cases 2) Conduct a review/rework 3) Establish a baseline 4) Carry out the test cases.

Techniques for Unit Testing

The following are some of the code coverage strategies used in unit testing −

• Coverage of the Statement

• Coverage of Decisions

• Coverage of Branches

• Coverage by Condition

• Coverage of Finite State Machines

Mock Objects as an Example of a Unit Test

Mock objects are used in unit testing to test pieces of code that aren't yet part of a full application. Mock objects stand-in for the program's missing elements. You could have a function that requires variables or objects that have not yet been generated. Those will be accounted for in unit testing in the form of fake objects produced specifically for the unit testing of that area of code.

Tools for Unit Testing

To help with unit testing, there is a variety of automated unit test tools available. We'll give you some samples below −

• Junit − is a Java programming language testing tool that is free to use. Assertions are provided to identify the test method. This utility initially tests the data before inserting it into the code.

• NUnit − NUnit is a popular unit-testing framework that supports all.NET languages. It's an open-source program that enables you to manually write scripts. It allows you to execute data-driven tests in parallel.

• JMockit − is a free and open-source unit testing software. It's a code coverage tool that includes measurements for lines and paths. It has recording and verification syntax for imitating APIs. Line coverage, Path coverage, and Data coverage are all available with this tool.

• EMMA − EMMA is a free and open-source toolset for evaluating and reporting Java code. Method, line and basic block are examples of coverage kinds supported by Emma. It is Java-based, therefore there are no external library requirements, and the source code is available.

• PHPUnit − PHPUnit is a PHP programmer's unit testing tool. It takes little chunks of code, known as units, and tests each one independently. The tool also enables developers to assert that a system behaves in a certain way using pre-defined assertion techniques

These are just a handful of the unit testing tools available. There are many more, notably for C and Java, but regardless of the language you choose, you will be able to find a unit testing tool to meet your requirements.

Unit Testing & Test Driven Development (TDD)

TDD makes considerable use of testing frameworks when it comes to unit testing. To generate automated unit tests, a unit test framework is utilized. Unit testing frameworks aren't exclusive to TDD, although they are critical to it. We'll look at some of the benefits of TDD in the field of unit testing below −

• Before the code is written, tests are written.

• Make extensive use of testing frameworks.

• The apps' classes are all put to the test.

• It is now possible to integrate quickly and easily.

The Myth of Unit Testing

Myth − It takes time, and I'm constantly overbooked.

My coding is impenetrable! Unit tests are unnecessary for me.

Myths are, by definition, erroneous assumptions. As a result of these assumptions, a vicious cycle emerges −

• Unit testing does, in fact, speed up development.

• Because programmers believe Integration Testing will detect all problems, they skip the unit test. Simple mistakes that might have been readily detected and repaired in unit testing require a long time to trace and fix after the units are combined.

The Benefits of Unit Testing

• Unit tests give a fundamental overview of the unit API for developers who want to discover what functionality a unit provides and how to utilize it.

• Unit tests give a fundamental overview of the unit API for developers who want to discover what functionality a unit provides and how to utilize it.

• We can test portions of the project without having to wait for others to finish due to the modular structure of unit testing.

Disadvantages of Unit Testing

• It's unrealistic to expect unit testing to detect every bug in software. Even in the simplest programs, it is impossible to assess all potential execution routes.

• By definition, unit testing focuses on a single piece of code. As a result, it is unable to detect integration or system-wide issues.

Unit testing should be done in combination with other types of testing.

Best Unit Testing Practices

• Cases for unit tests should be self-contained. Unit test cases should not be impacted by any upgrades or changes in requirements.

• Only one code should be tested at a time.

• For your unit tests, use explicit and consistent naming standards.

• Before modifying the implementation of any module, make sure there is a matching unit Test Case for the module and that the module passes the tests.

• Before moving on to the next step of the SDLC, any bugs discovered during unit testing must be resolved.

• Adopt a "test as code" strategy. The more code you write without testing, the more pathways you'll have to go through to look for issues.

Summary

Unit Testing is a sort of software testing in which individual software units or components are tested.

As you can see, unit testing may be somewhat time-consuming. Depending on the application being tested and the testing methodologies, tools, and philosophies employed, it might be complicated or simple. On some level, unit testing is always required. That is undeniable.