What Are Unit Testing And Its Types?

Types Of Unit Testing

How Many Types Of Unit Testing Are There?

Considered the first level of software testing life cycle (STLC), unit testing is performed before executing integration tests. This testing aims to validate the correctness and completeness of the smallest component of the software- Unit, the smallest possible testable part of the software that can accept and produce and output, respectively. Integration occurs to enable these units to form the modules or the system.

This process, performed by a selected group of software developers, unit testing, involves the evaluation of each unit before it is integrated into the system. These units are verified and validated based on specified requirements by security testing them in isolation to identify, analyze and fix defects.  

Table of Content:

  1. The necessity of unit testing 
  2. Features
  3. Kinds of unit testing
  4. How unit testing is done 
  5. Techniques used in unit testing 
  6. Obstacles faced
  7. Advantages and disadvantages 
  8. Unit testing Framework and tools
  9. What to consider in unit testing 
  10. Conclusion 

The Necessity Of Unit Testing 

It is effective testing, which may prove economical in the software development process, in comparison to detecting the defects present in the integrated system is a lot more complicated. In contrast, it is easier to find the bugs and defects in the smaller units. This Early detection of the bugs in the development process enables the developer to be able to fix them at the initial stage of the development process, thereby saving both time and cost of the project.

Additionally, with the assistance of this testing technique, the team of software developers can tackle various issues that are related to the software product, as it is focused on: 

  • It helps you Handle errors and defects.
  • It helps you Ensure the functional correctness and completeness of the software product.
  • It helps you Check input values and correct output data.
  • It helps you Optimize algorithms and performance testing.
  • It helps you identify, analyze, and rectify defects. 

Unit Testing Features

Unit Testing Features

The objective is to test each unit of the software product independently; thus, this testing is executed during the first or initial stage of software testing in the development cycle. This testing is an integral part of computer programming and is utilized to evaluate the individual units of the product’s open source code. 

The other features of this technique include: 

  1. It is Performed before the integration testing; unit testing is also referred to as component testing.
  2. Load testing is a component of test-driven development.
  3. It also forms the foundation of extreme programming, as it excessively relies on automated unit test frameworks.
  4. Evaluate individual units of the software product.
  5. The software developers write the test and run the test for testing so they can validate the compliance of the software code with its design alongside ensuring its intended function.
  6. It may also include techniques such as walk-through, review, and inspection of programming code.
  7. Demands strict possible test plans may also be needed for each isolated unit to produce effective results.
  8. Usually, automated testing is preferred for this testing type. However, manual testing can also be used for this type of testing.
  9. It will require plenty of time and patience on your part to focus and perform testing on each unit.
  10. You are provided with access to an effective testing approach to trace & resolve the errors in the programming code base at an earlier stage.
  11. It helps you save time and cost of finding and resolving the error at a later complex stage.

How Unit Testing Is Done 

Although the unit testing process is generally performed by the software developers or their peers, in some rare cases, this may also be executed by a team of testers. Whether the system testing is performed manually or through automated tools, it follows a set process, which usually consists of the following activities:

  • Defining and creating Unit Test Plans.
  • Unit test cases are designed and prepared based on the specified test plans.
  • There is the execution of these test cases on individual units.
  • Fix bugs (if any are found), and re-evaluate the unit.
  • This cycle of Testing keeps on repeating until the unit gets rid of all the bugs.

Kinds Of Unit Testing

Types of Unit Testing

There are three types of testing that can help the unit testers test each source code unit in isolation. Each of these types of unit testing caters to different requirements of the software and ensures its proper functioning. The types of unit testing include: 

Black Box Testing: This type of testing that enables the team to test the software’s user interface and its input and output. The tester is usually conscious of internal functionality in this kind of testing. It is the internal structure of an item or function to be tested is that is justify unknown to them.

White Box Testing: The White box testing is an important type of testing that is utilized by the developers who want to test the functional behavior of the software product and validate its execution.

Gray Box Testing: Is the third type of testing, gray box testing, is utilized to execute test suite and test cases, test various test methods, and perform a risk assessment. 

It’s referred to as semi-transparent Testing. It is a combination of White Box and Black box testing. This combination is the type of testing in which the tester is aware of a method or unit’s internal functionality, but not at a more profound level like white box testing. In this, the (user acceptance testing) user is partially aware of the internal functionality of a system. Various types of Testing coverage under a Gray box testing is mentioned as follows –

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

Unit Testing Techniques

Techniques Used In Unit Testing 

Developers can execute the process of unit testing with the assistance of three important techniques, which are:

Structural Technique

A white box testing technique utilizes the knowledge of the software system’s internal implementation and structure to design and create test cases. Then during the testing, the testers should have in-depth knowledge of the code coverage to facilitate test execution; thus, it is performed by the team of developers, with the assistance of the following methods:

  1. Branch Testing.
  2. Path Testing.
  3. Condition Testing.
  4. Expression Testing.
  5. Statement Testing.

Functional Testing Technique

Performed to validate the software product’s functionality and ensure it behaves in an intended manner; the team executes functionality testing. It is a black-box testing technique that involves the following: 

  1. Equivalence Partitioning.
  2. Boundary Value.
  3. Syntax Checking.
  4. Input domain testing.

Error Based Techniques

The Issues that are present in a code can be best tracked by the individual who designed it. For this, error-based techniques are used, which allow the team to identify defects, bugs, and other discrepancies in the software. It involves:

  1. Fault Seeding.
  2. Mutation Testing.
  3. Historical Test Data.

What Can I Do With Them?
Hammers are great tools to help you with various jobs — opening car windows or turning off alarm clocks. They can do many different things; they should probably only do a few. However, they are especially well suited to putting nails through hard surfaces. Tests are similar.

Test-Driven Development

Test-Driven Development (TDD)

Test-Driven Development, also called TDD, is a code design technique where the programmer writes a test before any production code is done and then writes the code that will make that test pass. The idea is that you gain a tiny bit of assurance that you have from that initial test / smoke test you do; the programmer can feel free to refactor and refactor some more to get the cleanest code that they know how to write. The idea is rather simple, but like most simple things, the execution is complex. TDD requires an entirely different mindset from what most developers are used to, as well as the tenacity required to deal with a learning curve that may slow you down at first.

Helps you in Checking Your Work
TDD is not new, but at this point, it is still mainly for the go-getters. Most of us are checking our work. After writing the production code, writing unit tests is the more traditional way of doing things, but it is no less valuable. It may also be something you are more familiar with if you have been in a math class any time in the past decade. 

After your work has been checked and it is clear that the code is doing what you think it is doing, it is normal that the value of the tests changes a little bit. Tests that can be efficiently run with every build of your product act as change detection, notifying you or your team when code changes in unexpected ways. 

Helps with the Code Documentation
Code documentation is often a drag, and it shows mostly how little code documentation gets written. Component testing (beta testing) can help make the documentation burden a little easier by encouraging better coding practices and leaving behind code pieces that describe what your product is doing. Rather than constantly feeding the documentation beast with a code change, you will be updating a system of checks working for you or your team instead.

Avoid the Danger Zone
There are minimal uses of unit testing techniques that you will want to avoid when possible—creating integration tests that You can do cross-system borders and touch databases or 3rd party systems quickly results in a test suite that takes a long time to run with each added test. There are several test frameworks out there that specialize in higher-level Testing. When you want to test larger pieces of your product at a time, you might want to investigate those other frameworks. 

One other risky area is an end to end tests. These usually require you to order carefully, dependencies on other tests, and a detailed setup to get your system in a particular ‘test ready’ state. Much like integration testing, there are several automation tools to choose from made just for this purpose. You can do these things with unit frameworks, but it might quickly become more work than it is worth.

TDD Test - Driven Development

Obstacles faced : While executing the component testing process, the team can encounter various issues and challenges, hindering the smooth testing and inhibiting the team from developing expected results. Several of the challenges witnessed by the testers include: 

  • They face Uncertainties or Trouble With Test Names: Names that don’t reflect the intent of the Testing or miscommunicate the test type can increase the challenge of Testing for your team. Furthermore, it can also increase confusion among team members, which further impacts the Testing of the software.
  • Challenges in Understanding the Entire Code: Software development requires excessive coding, and understanding the entirety of the code can be extremely difficult and tedious for the developers. Furthermore, it can delay the process of testing and product release.
  • Facing Problems With the Test Doubles: In this case, if the mock codes require more Testing than the production code, then this is a good indicator that there is an issue in the product, as these mock objects aim to simplify the process of Testing.
  • Being able to Find Dependencies: Finding dependencies in the software product can be a hassle-free task, hindering the testing process.
  • If they have Frequent debugging of Tests: Debugging is a complex task that requires great effort and time. Hence, if the tests fail constantly and it is often required that testing and debugging occur, it can increase the software’s challenges.

Advantages and Disadvantages of Unit Testing 

One can gather a proper understanding of a process by getting an insight into its advantages and disadvantages. Ergo, to help you better understand unit testing, here are its advantages and disadvantages. 

The Benefits of Unit Testing: Disadvantages of Component Testing:
  • This testing reduces the cost of Testing, as defects are identified and fixed in the early stages of development.
  • It also allows Testing of individual parts of the software.
  • A team can execute unit testing before the culmination of the development process.
  • It eliminates the dependencies on other modules.
  • In unit testing, the code is modular, making them more reusable.
  • Due to the testing’s modular nature, the team can test a part of the project without waiting for the others to be complete.
  • This testing validates the quality and accuracy of the program code.
  • The testing facilitates change, simplifies documentation, as well as integrates.
  • You can use programming languages such as Java.
  • The testing increases the reliability of the code.
  • It also simplifies the debugging process.
  • Unit testing cannot be used for the comprehensive detection of errors in the program.
  • The team can’t analyze and evaluate every execution path in the software.
  • As unit testing focuses on evaluating the smallest component of the software, it does not perform integration testing.
  • There can be a difference in the platform, as the product is not developed and tested on the platform where it will be deployed.
  • It requires the team to maintain rigorous discipline throughout the process to ensure the compliance of actual and expected results.

How to Adopt Unit Testing?

Adopt Unit Testing

Unit test cases are automated software testing but still created manually; for you to do Testing with a testing automated approach, the following steps will need to be considered – You can write another piece of code in your application to test a function (application testing). To do this, unit test cases were created. Later on, this section of code was finally removed to test code when an application is complete or when an application is working.

Isolation of a code: This Isolate function is put to the test more rigorously. The code can do Automated Unit Testing in a better way. Isolating functions/code aids in Testing in a good way. Because it helps to reveal dependencies between code functions, you can use the Test framework for developing automated test cases. During cases, the framework display logs for failed cases. Nowadays, many frameworks automatically flag and report failed cases in summary. Depending upon failure, failure may halt subsequent testing. 

Unit Testing Framework and Tools 

One of the most critical advantages of unit testing is that it is often executed with the aid of testing tools and frameworks, which increase its effectiveness and efficiency. For instance, stubs. The benefits of utilizing a unit testing tool are numerous: from making the process agile and robust to helping the team get accurate results. Because tools are an essential part of unit testing, we have listed some of the most popular unit testing tools available to you in the IT industry/market.

Hence, the popular unit testing tools include:

  1. JUnit.
  2. NUnit.
  3. JMockit.
  4. REST Assured.
  5. Selenium.
  6. EMMA.
  7. Quilt HTTP.
  8. Spock Framework.
  9. Cucumber.
  10. DBUnit.
  11. HTMLUnit.
  12. PHPUnit.
  13. SimpleTest.

What to Consider in Unit Testing

Unit Testing

While performing unit testing, there are manifold aspects that need proper consideration and monitoring to validate the quality, effectiveness, and accuracy of Testing. Hence, here are some critical things you should consider while executing uni testing: 

  • Testing should be performed independently; this is done to ensure that any modifications and changes that are implemented in the software requirements are not affecting the unit test cases.
  • The test execution process needs to be concentrated on one code at a time.
  • Any of the bugs and defects detected by the team during the testing process should be resolved and fixed before there is any commencement of the next phase of the software testing life cycle (STLC).
  • Your Test cases need to be both comprehensive and understandable.
  • Your testing environment needs to be isolated from the development environment in unit testing.
  • You and your team should find an appropriate and effective tool for the process of Testing.
  • Perform rigorous and frequent unit tests. 


From software’s functionality, stability, performance, and reliability to its compliance with privacy policy, standards, and more, there are numerous aspects of a software product that are ensured through Testing, and enhance your testing strategy. It ensures the product’s code and functionality and makes the software reliable and efficient. The Unit tested also plays a crucial integral part in the process of validating the quality assurance and effectiveness of the software. Hence, the team needs to execute unit testing; including integrity testing, alpha testing, ai testing, compatibility testing, digital testing, sanity testing, and continuous integration, during the early stages of the software development life cycle (SDLC). Also, ensure that you identify a detailed comparison between Unit Testing and API Testing and enhance your knowledge efficiently.

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