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Unit Testing Techniques and Best Practices | Ultimate Guide

Navdeep Singh Gill | 27 Nov 2023

Unit Testing Techniques and Best Practices

What is Unit Testing?

It is a type of testing in which individual units or functions of software testing. Its primary purpose is to test each unit or function. A unit is the smallest testable part of an application. It mainly has one or a few inputs and produces a single output. In procedural programming, a unit is referred to as an individual program, while object-oriented programming languages include Base/Superclass, abstract class, and Derived/Child class takes place. Unit test frameworks, drivers, stubs and mocks /fake objects used in it. It works based on a White box technique. With Unit Testing Enterprises can -
  • Improve Quality of Code
  • Build Reusable and Reliable Code
  • Simplify Documentation
  • Enable Seamless Integration

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How does it function?

To do this, mocks are required. Is there a need for mocks to make testing on functions? Yes, without creating mock functions, they cannot be unit-tested. Testing works based on mock objects. Mock objects work to fill in for missing parts of a program. For example, there might be a function that needs variables or objects that have not been created yet. To test the function, mock objects are created. In such conditions, mock objects fill in missing parts. Techniques within it

White-Box testing

It's referred to as glass box testing/transparent testing. In this type of testing, the tester is aware of internal functionality. The internal structure of an item or function to be tested is unknown.

Black-Box testing

It is a type of testing the tester is not aware of the internal functionality of a system. The internal structure of the function to be tested is unknown.

Gray-Box testing

It's referred to as semi-transparent testing. It is a combination of Black Box and White Box testing. It is the type of testing in which the tester aware of the internal functionality of a method or unit but not at a deeper level like white box testing. In this, the user is partially aware of the internal functionality of a system. Different type of testing covered under Gray box testing is mentioned as follows -
  • Matrix testing.
  • Pattern Testing.
  • Orthogonal Pattern testing.
  • Regression Testing.

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What advantages does Unit Testing offer?

Unit Tests reveal a basic understanding of API units or functions to understand the functionality of the code. It is a way to write test cases for all functions and methods so that whenever a change causes a fault, then in that case, bug quickly identified and fixed. A modular approach followed in testing, single-single functionality or part of the code tested without waiting for other of code to be completed.

What makes Unit Testing crucial?

It is a type of testing that increases the speed of testing. It helps to maintain and change the code. If good unit test cases are written for code and run every time the code changes, any defect is revealed after the code changes. Regulations should be in a more reusable way; in a modular way more unit testing will be possible. Writing test cases takes time but, this thing can be compensated by less amount of time it takes to run the tests.

Unit tests are more reliable, and development will be faster in the long run too. It makes debugging easy. In this when a test fails, then only the latest changes need to be debugged. With testing at a higher level or higher phases, changes made over many days/ weeks/months need to be scanned or detected. The cost to fix detected bugs during Testing lesser in comparison to the defects at higher levels. Compare the cost to fix a defect when a bug detected in a phase of unit testing with the same bug detected in User Acceptance Testing. The effort required to find and fix defects found during Unit Testing is less in comparison to the effort required to fix defects found during System Testing or Acceptance Testing.

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How to adopt it?

To do this, unit test cases created. Unit test cases automated but still created manually. To do Unit Testing with an automated approach following steps need to be considered - Write another section of code in an application to test a function. Later on, this section of code finally removed to test code when an application is complete or when an application is in a working state.

Isolation of a code - Isolate function to test it more rigorously. Isolate code to do Automated Unit Testing in a better way. Isolating functions/code helps to do testing in a good way. It helps to reveal dependencies between functions of code. Use the Test framework for developing automated test cases. During the execution of test cases, framework display logs for failed test cases. Nowadays, many frameworks automatically flag and report in summary for failed test cases. Depending upon failure, failure may halt subsequent testing.

What are the best practices?

There is no need to create test cases for every condition. Instead of that focus on tests that impact the behavior of the entire system. Before fixing a bug, write a test the exposes the defects.
  • The bug will re-occur if not appropriately cached.
  • Test suites should be more comprehensive.
  • Write test cases before fixing the defect.
  • Write test cases independent of each other. For example, if a code class depends upon a database, do not write a topic interacting with a database to test a class. Instead, create an abstract interface around that database connection and implement an interface with a mock object.
  • The most important thing for unit testing is to cover all the paths. It is also required to pay attention to loop conditions.
  • Write cases to verify behavior and test cases to ensure the performance of the code.
  • Execute test cases continuously and frequently.

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What are the best tools for Unit Testing?

The best tools for unit testing are listed below:


Parasoft Jtest is an IDE plugin that leverages an open-source framework (JUnit,mockito, PowerMock, and Spring) with guided and also provides one-click actions to create, scale, and maintain unit tests. Automating the time-consuming aspects of Unit Testing, focuses on business logic and creates more meaningful test suits.


It is a tool that is free to use for Java programming language. It also provides support for assertions to identify test methods. JUnit is a type of tool that tests data first and then inserts it into a piece of code.


It's used as a Testing framework, and this tool is used for all.Net languages. It is an open-source tool to write scripts manually. NUnit supports data-driven tests run in parallel.


It is an open-source testing tool. JMockit is a code coverage tool. It helps in mocking of API with recording and verification of syntax. It is a type of tool that offers line coverage, path coverage, and data coverage.


It is an open-source toolkit for analyzing and reporting code written in a Java language. EMMA supports coverage types like method, line, and basic block. It is a Java-based tool.

PHP Unit

It is a Testing tool for the PHP language. It takes small portions of code called as units and tests each team separately. This testing tool uses pre-defined assertion methods to assert that the system should behave in a specific manner.

Java vs Kotlin
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In conclusion, this testing is only required to test each function independently. This type of testing saves time and cost. If the same issue is faced at Acceptance Testing then, in that case, the price will be more as compared to the cost of Unit Testing. Sometimes, to do Testing, there is a requirement to create mock objects to satisfy or fulfill the dependency of a method or a function. If a function is dependent on another function and another function is still not created, then the mock function object is used. You would also love to learn more about: