What is Unit Testing? | Unit testing on the frontend? |Guide 2023

Introduction

Unit Testing is a type of software testing that tests individual components or units of code to verify their behavior. Unit testing on the front end involves verifying individual components and functions to ensure they are working as expected. This can include things like checking the functionality and behavior of forms, menus, reports, graphs, and associated Javascript. Unit Testing is usually done during the development cycle by the developer. In 2022, there are a number of guides available to help you with unit testing on the front end.

Unit Testing is a software testing technique by means of which individual units of software i.e. A group of computer program modules, usage procedures, and operating procedures are tested to determine whether they are suitable for use or not. This is a testing method used by which every independent module is tested to determine if there is an issue with the developer himself. It correlates with the functional correctness of the independent modules. Unit Testing is defined as a type of software testing where individual components of the software are tested. Unit Testing of the software product is carried out during the development of an application. An individual component may be either an individual function or a procedure. Unit Testing is typically performed by the developer. In SDLC or V Model, Unit testing is the first level of testing done before integration testing. Unit testing is a type of testing technique that is usually performed by developers. However, due to the reluctance of developers to test, quality assurance engineers also do unit testing.

Unit testing is a component of test-driven development (TDD), a pragmatic methodology that takes a meticulous approach to building a product by means of continual testing and revision. This testing method is also the first level of software testing, which is performed before other testing methods such as integration testing. Unit tests are typically isolated to ensure a unit does not rely on any external code or functions. Testing can be done manually but is often automated.

How unit tests work?

A unit test typically comprises of three stages: the plan, case & scripting, and the unit test itself. In the first step, the unit test is prepared and reviewed. The next step is for the test cases and scripts to be made, then the code is tested.

Test-driven development requires that developers first write failing unit tests. Then they write code and refactor the application until the test passes. TDD typically results in an explicit and predictable code base.

Objectives of Unit Testing:

1. To isolate the section of the code.
2. To verify the correctness of the code.
3. Test every function and procedure.
4. Fix bugs early in the development cycle and save costs.
5. Help the developers understand the code base and enable them to make changes quickly.
6. To help with code reuse.

Unit Testing lifecycle:

Unit Testing Techniques:

The Unit Testing Techniques are mainly categorized into three parts which are Black box testing which involves testing of user interface along with input and output, White box testing which involves testing the functional behavior of the software application and Gray box testing which is used to execute test suites, test methods, test cases and performing risk analysis.

The code coverage techniques used in Unit Testing are listed below:

• Statement Coverage
• Decision Coverage
• Branch Coverage
• Condition Coverage
• Finite State Machine Coverage

In other ways:

• Black Box Testing — Using which the user interface, input, and output are tested.
• White Box Testing — used to test each one of those functions' behavior is tested.
• Gray Box Testing — Used to execute tests, risks, and assessment methods.

Benefits of unit testing:

Writing software unit test code provides quick, almost instantaneous feedback about the correctness of the coding, including its design and implementation. Test passes and the test fails to confirm if the software works or doesn’t work as intended and can update its vetting every time someone changes a specific piece of code.

Unit testing saves time and money by fixing problems early in the development process, as opposed to later during system testing, integration testing, and even beta testing.

Other benefits of unit testing include:

• It gives developers insight into the testing code base, so they can make any code changes quickly.
• More bugs caught early in the process enable the development team to spend less time debugging later and more time creating value with their work.
• New team members can get up to speed more easily, without having to worry about damaging existing code, because any problems will be caught quickly.
• A well-constructed unit test can be used as documentation, which is updated each time the test is run.
• Because each unit test is a standalone function, it can test different parts of a project without waiting for others to be completed.
• Catching errors while working on part of a project makes it easier to solve problems quickly since you’re already focused on the task.

Unit Testing Tools

There are several automated unit test software available to assist with unit testing. We will provide a few examples below:

1. Junit: Junit is a free-to-use testing tool used for the Java programming language. It provides assertions to identify the test methods. This tool tests the data first and then inserts it into a piece of code.
2. NUnit: NUnit is a widely used unit-testing framework use for all .net language. It is an open-source tool that allows writing scripts manually. It supports data-driven tests which can run in parallel.
3. JMockit: JMockit is an open-source Unit testing tool. It is a code coverage tool with line and path metrics. It allows mock APIs with recording and verification syntax. This tool offers Line coverage, Path Coverage, and Data Coverage.
4. EMMA: EMMA is an open-source toolkit for analyzing and reporting code written in Java language. Emma supports coverage types like methods, lines, and basic blocks. It is Java-based so it is without external library dependencies and can access the source code.
5. PHPUnit: PHPUnit is a unit testing tool for PHP programmers. It takes small portions of code called units and tests each of them separately. The tool also allows developers to use pre-define assertion methods to assert that a system behaves in a certain manner.

These are just a few of the available unit testing tools. There are lots more, especially for C languages and Java, but you are sure to find a unit testing tool for your programming needs regardless of the language you use.

Test Driven Development (TDD) & Unit Testing

Unit testing in TDD involves extensive use of testing frameworks. A unit test framework is used to create automated unit tests. Unit testing frameworks are not unique to TDD, but they are essential to it. Below we look at some of what TDD brings to the world of unit testing:

• Tests are written before the code
• Rely heavily on testing frameworks
• All classes in the applications are tested
• Quick and easy integration is made possible

Unit Testing Myth

Myth: It requires time, and I am always overscheduled
My code is rock solid! I do not need unit tests.

Myths by their very nature are false assumptions. These assumptions lead to a vicious cycle as follows –

The truth is Unit testing increases the speed of development.

Programmers think that Integration Testing will catch all errors and will not execute the unit test. Once the units are integrated, very simple errors that could have been very easily found and fixed in the unit tested take a very long time to be traced and fixed.

Unit testing best practices

To get the most out of unit testing, here are some best practices that range from embracing simplicity to developing a fast-testing structure and consistent naming convention.

1. Only test one code

When writing unit tests, make sure they are designed to test one thing at a time, isolating a unit and making sure it works. While there are tests that tackle more than one unit at a time, these are called integration tests.

2. Ensure that tests are not complex

The more complex a testing code is, the more likely it will have bugs. If one of your goals is to keep the app development code simple, the unit testing code should be the same. Keeping its cyclomatic complexity low is one good practice.

3. Create consistent naming

Consider adopting a consistent naming convention that makes sense for the development team. It should be easy to understand, remember, and convey what the test method is about.

4. Develop a fast-testing structure

A unit test should be developed to run quickly, preferably measured in milliseconds rather than seconds. If they go longer, developers will be reluctant to use them, which defeats the purpose of having this safety net in place.

5. Remember tests should be reliable

Unit test codes must be reliable or else they defeat the purpose. As stated, keep them simple and use clear standard naming conventions to help prevent mistakes. Unit test fails shouldn’t happen because they’re written by the developer, who has detailed knowledge of the inner workings of how a feature was implemented. The test otherwise might fail because of requirement changes or implementation problems.

Tests should have clear outcomes and next steps

A good unit test must have an expected outcome and an actual outcome. How is the code supposed to function and how does this differ during testing? Seeing how reality differs from expectation, offers a clear pathway for fixing bugs and problems so that the two are aligned.

Advantages and disadvantages of unit testing

Advantages of unit testing include:

• The earlier a problem is identified, the fewer compound errors occur.
• The cost of fixing a problem early can quickly outweigh the cost of fixing it later.
• Debugging processes are made easier.
• Developers can quickly make changes to the code base.
• Developers can also reuse the code by migrating it to new projects.

Disadvantages include:

• Tests will not uncover every bug.
• Unit tests only test sets of data and their functionality — they will not catch errors in integration.
• More lines of test code may need to be written to test one line of code — creating a potential time investment.
• Unit testing may have a steep learning curve, for example, having to learn how to use specific automated software tools.

Summary

• UNIT TESTING is defined as a type of software testing where individual units or components of the software are tested.
• As you can see, there can be a lot involved in unit testing. It can be complex or rather simple depending on the application being tested and the testing strategies, tools, and philosophies used. Unit testing is always necessary on some level. That is a certainty.

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