How to run Java Unit Test cases with Apache Maven?

If you are working with a Apache Maven Java project and want to run your unit test cases, you would need to do the following,

1. Add Java JUnit dependencies to pom.xml

Open pom.xml file and the junit dependency as highlighted in bold, you can find the details on official JUnit website: https://junit.org/junit4/dependency-info.html

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 \
         http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>maven-juit-proj</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.1</version>
        </dependency>
    </dependencies>

</project>

2. The Java Project Structure

I am using Idea IntelliJ IDE on macOS, and my project structure is as below,

HelloWorld.java

public class HelloWorld {

    public String greeting(String name) {
        return "Hello, " + name;
    }
}

HelloWorldTest.java

import org.junit.Test;
import org.junit.Assert;

public class HelloWorldTest {

    private HelloWorld hello = new HelloWorld();

    @Test
    public void test() {
        Assert.assertEquals("Hello, Neo", hello.greeting("Neo"));
    }
}

3. Running Maven Test

Now that we have our simple HelloWorld class and its HelloWorldTest class ready with the JUnit 4 dependency set in our pom.xml we are ready to run our text using maven commands,

⛔️ Make sure Maven is installed on your computer if not check out this article: How to install maven in macOS using Terminal Command

✏️ Command: mvn test - to run all the test cases in our project

code2care@mac maven-juit-proj % mvn test
[INFO] Scanning for projects...
[INFO] 
[INFO] --------------------< org.example:maven-juit-proj >---------------------
[INFO] Building maven-juit-proj 1.0-SNAPSHOT
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ maven-juit-proj ---
[WARNING] Using platform encoding (US-ASCII 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) @ maven-juit-proj ---
[WARNING] Using platform encoding (US-ASCII 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) @ maven-juit-proj ---
[INFO] Changes detected - recompiling the module!
[WARNING] File encoding has not been set, using platform encoding US-ASCII, i.e. build is platform dependent!
[INFO] Compiling 1 source file to /Users/code2care/IdeaProjects/maven-juit-proj/target/classes
[INFO]

Downloading from central: 
https://repo.maven.apache.org/maven2/org/apache/maven/surefire/surefire-junit4/2.12.4/surefire-junit4-2.12.4.pom
https://repo.maven.apache.org/maven2/org/apache/maven/surefire/surefire-junit4/2.12.4/surefire-junit4-2.12.4.pom 
https://repo.maven.apache.org/maven2/org/apache/maven/surefire/surefire-providers/2.12.4/surefire-providers-2.12.4.pom
https://repo.maven.apache.org/maven2/org/apache/maven/surefire/surefire-providers/2.12.4/surefire-providers-2.12.4.pom
https://repo.maven.apache.org/maven2/org/apache/maven/surefire/surefire-junit4/2.12.4/surefire-junit4-2.12.4.jar
https://repo.maven.apache.org/maven2/org/apache/maven/surefire/surefire-junit4/2.12.4/surefire-junit4-2.12.4.jar

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running HelloWorldTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.04 sec
Results :

Tests run: 1, Failures: 0, Errors: 0, Skipped: 0

[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  2.241 s
[INFO] Finished at: 2021-02-13T14:51:48+05:30
[INFO] ------------------------------------------------------------------------

Let's add one more test case that would fail,

    @Test
    public void test2() {
        Assert.assertEquals("Hello, Neo", hello.greeting("Sam"));
    }

mvn test output:

Running HelloWorldTest
Tests run: 2, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 0.038 sec <<< FAILURE!
test2(HelloWorldTest)  Time elapsed: 0.003 sec  <<< FAILURE!
org.junit.ComparisonFailure: expected:<[Hello, Neo]> but was:<[Sam]>
        at org.junit.Assert.assertEquals(Assert.java:117)
        at org.junit.Assert.assertEquals(Assert.java:146)
        at HelloWorldTest.test2(HelloWorldTest.java:15)
        at java.base/java.lang.reflect.Method.invoke(Method.java:564)
        at org.junit.runners.ParentRunner.runChildren(ParentRunner.
        ....
        at java.base/java.lang.reflect.Method.invoke(Method.java:564)
        at org.apache.maven.surefire.util.ReflectionUtils.invokeMethodWithArray(ReflectionUtils.java:189)
        at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:115)
        at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:75)

Results :

Failed tests:   test2(HelloWorldTest): expected:<[Hello, Neo]> but was:<[Sam]>

Tests run: 2, Failures: 1, Errors: 0, Skipped: 0

[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  0.760 s
[INFO] Finished at: 2021-02-13T15:24:00+05:30
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.12.4:test (default-test) on project maven-juit-proj: There are test failures.
[ERROR] 
[ERROR] Please refer to /Users/code2care/IdeaProjects/maven-juit-proj/target/surefire-reports for the individual test results.
[ERROR] -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException

✏️ Command: mvn -Dtest=<Test-Class-Name> test

To run individual test,

Example:

$ mvn -Dtest=HelloWorldTest test

✏️ Command: mvn -Dtest=<Test-Class-Name-1>,<Test-Class-Name-2 test

To run multiple tests at once.

Example:

$ mvn -Dtest=HelloWorldTest, HelloWorldTest2 test

✏️ Command: mvn -Dtest=<Test-Class-Name-1>#methodName test

To run a particular test method from a class.

Example:

$ mvn -Dtest=HelloWorldTest#test test

✏️ Command: mvn -Dtest=<Test-Class-Name-1>#methodName* test

To run all test methods what that matches the regular expression,

Example:

$ mvn -Dtest=HelloWorldTest#test* test

The above will run test and test1 methods from class HelloWorldTest