Create JUnit Test Cases using Maven Project

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In this article, we will learn how to write a unit test. We will create a simple maven project to demonstrate how to create JUnit test cases.

We don't use any IDE to create a maven project instead we will use the command line to create a simple maven project. If you want to know how to create a maven project using Eclipse IDE then refer to the How to Create a Simple Maven Project in Eclipse tutorial.

1. Create Simple Maven Project

Let's create a simple maven project by executing the below command:

mvn archetype:generate -DgroupId=org.yourcompany.project -DartifactId=application 

After the maven project builds success, maven will create a default folder structure.

2. Project Packaging Structure

src

• src/main/java – This folder contains Java source code packages and classes
• src/main/resources – This folder contains non-java resources, such as property files and Spring configuration

Test

• src/test/java – This folder contains the test source code packages and classes
• src/test/resources – This folder contains non-Java resources, such as property files and Spring configuration

── pom.xml └── src ├── main │ ├── java │ │ └── com │ │ └── javadevelopersguide │ │ └── junit │ │ └── Calculator.java │ ├── resources └── test ├── java │ └── com │ └── javadevelopersguide │ └── junit │ └── CalculatorTest.java └── resources 

3. Update JUnit Dependencies in pom.xml File

Let's add below JUnit dependency to our maven project. Open the pom.xml file and add below dependency in the dependencies section:

<dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> <scope>test</scope> </dependency>

4. Create Calculator.java class

Let's create a Calculator class with some logic so that we will unit test it using JUnit framework:

public class Calculator { public int evaluate(String expression) { int sum = 0; for (String summand : expression.split("\\+")) sum += Integer.valueOf(summand); return sum; } }

Create a JUnit Test for Calculator Clas

Two steps required to create a simple test case.

1. Create a method and annotate a method with @org.junit.Test
2. When you want to check equality, import org.junit.Assert.* statically, call assertEquals(), and pass expected and actual values.

Here is the complete code:

import static org.junit.Assert.assertEquals; import org.junit.Test; public class CalculatorTest { @Test public void evaluatesExpression() { Calculator calculator = new Calculator(); int sum = calculator.evaluate("1+2+3"); assertEquals(6, sum); } }

5. Run the test

Run the JUnit test with below maven command using command line:

mvn test 

Output:

[INFO] Scanning for projects... [INFO] [INFO] ------------------------------------------------------------------------ [INFO] Building junit-getting-started 0.0.1-SNAPSHOT [INFO] ------------------------------------------------------------------------ [INFO] [INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ junit-getting-started --- [WARNING] Using platform encoding (Cp1252 actually) to copy filtered resources, i.e. build is platform dependent! [INFO] Copying 0 resource [INFO] [INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ junit-getting-started --- [INFO] Changes detected - recompiling the module! [WARNING] File encoding has not been set, using platform encoding Cp1252, i.e. build is platform dependent! [INFO] Compiling 1 source file to E:\Git_Work\junit-developers-guide\junit-getting-started\target\classes [INFO] [INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ junit-getting-started --- [WARNING] Using platform encoding (Cp1252 actually) to copy filtered resources, i.e. build is platform dependent! [INFO] Copying 0 resource [INFO] [INFO] --- maven-compiler-plugin:3.1:testCompile (default-testCompile) @ junit-getting-started --- [INFO] Changes detected - recompiling the module! [WARNING] File encoding has not been set, using platform encoding Cp1252, i.e. build is platform dependent! [INFO] Compiling 1 source file to E:\Git_Work\junit-developers-guide\junit-getting-started\target\test-classes [INFO] [INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ junit-getting-started --- [INFO] Surefire report directory: E:\Git_Work\junit-developers-guide\junit-getting-started\target\surefire-reports ------------------------------------------------------- T E S T S ------------------------------------------------------- Running com.developersguide.junit.CalculatorTest Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.069 sec Results : Tests run: 1, Failures: 0, Errors: 0, Skipped: 0 [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESS [INFO] ------------------------------------------------------------------------ [INFO] Total time: 17.022 s [INFO] Finished at: 2018-06-27T21:49:29+05:30 [INFO] Final Memory: 11M/28M [INFO] ------------------------------------------------------------------------ 

Conclusion

In this article, we have learned how to write a simple JUnit test case by creating a maven project. You can apply more asserts to these examples and have a hands-on experience. The source code available for this guide on GitHub.

GitHub Repository: JUnit Developers Guide

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JUnit 4 Tutorial

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