Launch with Confidence: A Detailed Java Unit Testing Process


Imagine that the wait to release your product is finally over!

You have the perfect product for your users. Fortunately, the overall user sentiments brim positivity, of course with a couple of glitches–understood, part and parcel of a product. However, the overall product is likeable and it speaks success.

Now, you sit down and analyze how far you have come with your product. Hundreds of bugs and code failures within the product have been overturned to success. And, you are glad that glitches that could easily catch eyes were identified and resolved at the right time.

This scenario sounds like the one you would have on your vision board while brainstorming about your product. However, when practicality meets your product idea, tagging technical difficulties and resource gaps along, you might be unsure about the final product.

Exactly at that point, if you invest all your energy into proper testing of our product, you can gain reassurance towards your initial product impression.

Is it that simple to create a winning product?–You may ask.

No. The key is to focus on user experience. If they can operate your software without any lag and as expected, you can expect a win there. And, testing helps a lot. While our rich repository and technical experts often talk about the development process, our QAs have made it a point to share their knowledge about Java unit testing and tools.

Read on to create a time-tested product with Java unit testing process and tools.

How to Set Up, Write, and Implement Java Testing?

In order to set up the testing framework, we will use JUnit. For adding it to your project, you will need a dependency manager.

💡 Quick definition: A dependency manager is a tool, helping you to download frameworks or libraries along with their dependencies for adding to your product. It also allows you to keep a track of a version you are using.

Step 1: Installation of Dependency Manager

Some of the best dependency managers are Maven and Gradle. So, installing Gradle or Maven is the first step to approach the Java unit testing process.

Check whether your dependency manager has been installed in your system, enter this command in your terminal:

For Gradle: $ which gradle

For Maven: $ which maven

When you input the command, it should output the directory showing Gradle/Maven installed in your system. This is the sign for you to move to the next step of the Java unit testing process.

Step 2: Adding JUnit 4 to Dependency Manager:

Adding JUnit 4 to Gradle: Add the following code to build.gradle.


Adding JUnit 4 to Maven: Add the following code to pom.xml. Here, you have to be extremely cautious about the version you are adding.


Adding JUnit 5 to Gradle


Adding JUnit 5 to Maven


Step 3: How to Write Java Unit Tests?

Since we have already installed and set up the prerequisites, the next step is to approach the construction and implementation of these tests. In order to illustrate how to write java unit tests, we will start with a basic function.

Consider the following program that converts Km to Miles.

package examples.nbank;

public class Conversion


public double distConversion (double distance, String unit)


if (unit.equals(“Km”))

return (distance * 0.621371);


return (distance * 1.60934);



Now, we will discuss the anatomy of JUnit code:

1) In the first section, we will focus on the imports for JUnit libraries required for the testing framework.

import static org.junit.Assert.assertEquals;

import org.junit.*;

These imported libraries can be about a particular functionality of a JUnit. However, these are commonly imported for having access to all the functionalities.

2) The second section has the beginning of our test class. In this section, it is crucial to focus on the naming convention that follows the ClassNameTest.

public class ConversionTest {

3) In this third section, we will focus on the first JUnit-specific syntax. These annotations are crucial during the creation of JUnits.


4) This @Test annotation denotes JUnit that the public void that it is attached to can now be run as a test case.

In this section as well, we will focus on the naming convention. Here the structure will be in the form of test-method-name.

public void testdistConversion() throws Throwable {

5) For this particular section, we will create a new instance for our class object. As a result, it is crucial to call the method that we are testing for the conversion of kilometers to miles. Without using the object instance, it is not possible to test the conversion method of distance.

Conversion underTest = new Conversion();

6) The variables related to the method are required to be established. As a result, we have to declare variables associated with our method. These variables need to be given meaningful values for the test to have meaning.

double distance = 80;
String unit = “”;

7) Here, you can avoid the variable declaration. However, it is valuable for better readability and organization. In this section, we assign the output of our method to the variable for assertion.

double result = underTest.distConversion (distance, unit);

8) The asserting method is a part of org.junit.Assert Class, which can be utilized to determine the fail or pass status of a test case. Here, only the assertions that fail are recorded. The sole objective of these assertions is to validate the variables.

assertEquals (128.748, result, 0.0);

Step 4: How Should you Run a JUnit?

Make your own choice!

In order to run a JUnit to approach the Java unit testing process, you have three ways to do so.

1) Using the command line:
For running a JUnit directly using the command line, you have to keep a few things in mind. You should have JDK for your path, raw JUnit jar file, as well as test cases. You can use the following command:

java -cp /path/to/junit.jar org.junit.runner.JUnitCore

2) Using IDE:

There are two IDEs that you can use to run a JUnit–Eclipse and Intellij.

If you want to run a JUnit using Eclipse, you have to locate your JUnit test using your Package Explorer. When you find it, right-click and use it to Run as Java Test. Upon clicking this, you will find it implementing your test and opening a new JUnit window if it is not open already.

If you want to run a JUnit through Eclipse, you have to follow similar steps as Eclipse and choose Run–’testName’. Similar to the process in Eclipse, you will see a JUnit window with the outcome of the test open.

3) Using a build system:If you have set up your JUnit test in Maven, you can use the following:

Run Complete Test Suite:

mvn test

Run Specific Test:

mvn -Dtest=TestName test

If you have set up your JUnit test in Gradle, you can use the following:

Run Complete Test Suite:

gradlew test

Run Specific Test:

gradlew -Dtest.single=testName test

How to Test a Java Application?

In this section, we will discover how to test a complete J2EE application. The test is carried out in several steps. For this particular test, we will talk about our previous example on distance conversion from km to miles.

Consider a single screen that asks you for a value to convert from km and returns output in miles. The screen will have an input number and enter option. For the test to be successful, the test cases should be able to cover all the conditional and loop statements. The test cases should be able to display the ideal results based on the variable added.

Below are some of the general test cases for you to implement. You can note down the results in your test document:

Sr.NoTest CaseExpected Result
1The user inputs a number to be turned into miles from kilometres and clicks on goA value multiplied by 0.6213 will be displayed on the screen.
2The user simply clicks go without entering a number.A screen with, “Please enter your value.” is displayed.
3The user enters an alphabet or a symbol instead of a number.A screen with, “Please enter the value in number.” is displayed

After analyzing these test cases, you might realize that you have to deal with the field testing, functionality, validations, and buttons of a specific screen. This is highly precise as Unit Testing deals with the testing of small code snippets as well as components.

Also, note that the above examples are only for test cases. You can define your own test cases based on your product.

What are the Best Practices to Approach Java Unit Testing Process?

For Java developers, Test Driven Development plays a crucial role in the designing and development of a product/software. The test-driven development enables the programmer in multiple ways.

The test-driven development enhances the code. It also helps in boosting the productivity of a Java developer. The test-driven development also helps in saving time that is otherwise wasted for rework. The TDD approach can be used to detect the error in a faster and quicker way. The Java developer can use TDD for writing small classes that can focus on a single functionality over the big classes.

Let’s take a look at the best practises for the Java unit testing process.

Naming Conventions:

The naming conventions assists in the organization of the Java unit tests in a better manner. There are numerous naming conventions in use. However, the gold is how you pick your naming convention. If you choose a popular naming convention, it would be easy to resonate with the newcomers in your team and they can find their way around quite easily.

In addition to this, segregate your execution from the test code so that the accidental packaging does not happen. Also, you can place the test cases using the same package as your execution. It is also advantageous to use a descriptive name for your test method.


The test-driven development processes are a key set of practices, which highly governs the Java unit testing process. It is crucial to write the Java unit test code before the implementation code. In addition to this, it also ensures that every written line of the code is being tested.

Another best practice to adopt is that when your testing is failing, do not go on detecting the error, it is good to start afresh and write a new code. Also, you should rerun all the tests every time the execution code is modified.

Development Practises:

It is indeed a great practice for the java Unit testing process to start with the simplest code for passing the test. Also, you can work on the assertions first for bringing more clarity to the requirement. You can reduce the assertions in every test since it will be hard to tell the one that has led to a test failure. Also, with multiple assertions, the objective of the test may be lost in value.

If you are finding it difficult, you can hire our experienced Java developer for the same.

What are the Best Testing Frameworks for Java Software?

In order to carry out the Java unit testing process in a successful manner, you have to identify the best testing frameworks with standardized, extensible, and sophisticated means. In this section, we will talk about the best testing frameworks that can help you carry out a seamless Java unit testing process:

JBehave is a commonly used testing framework for the Java unit testing process. It supports behaviour-driven development, which is an evolution of test-driven development and acceptance test-driven development. It serves the purpose of BDD through the integration among various development teams.

The unit testing framework can be used with Java 5 or any other version. It is chiefly used by experts for testing small nuggets of code. It contains test runners, JUnit classes, fixtures, and test suites. The testing framework can be used for integration testing and unit testing since it supports Java 8 features.

Serenity is one of the most popularly used testing frameworks for the Java unit testing process. It helps you to write acceptance tests in a manageable, structured, and cleaner manner. The testing framework for the Java unit testing process features complete reports on the test outcomes as well as implementations.

TestNG enables you to create and run parallel testing on numerous code snippets. The priorities can be set through data parameterization and the use of annotations. In addition to this, TestNG also enables you to develop HTML reports through the organization and grouping of priorities.

Selenide is one of the best testing frameworks for the Java unit testing process. It features time-saving opportunities with the configuration of CI tools like Jenkins. Selenide makes the test precise as well as stable by resolving the timing problems.

Confused about the best framework to use for the Java unit testing process?

Ask our experts

How to Approach Successful Java Unit Testing?

Developing highly performant Java software is easy if you bring your Java unit testing game to A level. The key is to have multiple test cases, depending on the potential user experience. You have to check its compatibility with multiple browsers and operating systems. In such a case, the best practice you can follow is to create a checklist that covers the comprehensive process.

More About Author

Vishal Nakum

Vishal Nakum is a tech enthusiast with a passion for exploring the latest developments in the world of technology. He has a keen interest in emerging technologies such as Artificial Intelligence, Machine Learning, and Blockchain, and enjoys keeping up-to-date with the latest trends and advancements in these fields. Vishal is an avid learner and is always on the lookout for new ways to expand his knowledge and skills. He is also a creative thinker and enjoys experimenting with new ideas and concepts. In his free time, Vishal enjoys playing video games and reading books on technology and science.