Posted by Recently, I had a task to migrate the unit tests in our project from ‘JUnit 4’ to ‘JUnit 5’. As many developers, I researched a bit to learn about the major differences between the two versions and drafted a plan for smooth migration.
From the first look, I thought my only job was refactoring the tests and probably some helper classes. But, I was wrong! I ran into a configuration issue with the maven-surefire-plugin configuration.
In this post, I will be sharing the encountered issue and its fix. Note that I will not cover the detailed steps of how to migrate from ‘JUnit 4’ to ‘JUnit 5’.
Tests run: 0!
We, as many other developers, use the maven-surefire-plugin to run our tests during the test phase of maven’s build lifecycle. We rely heavily on this plugin because it fails the build when one of the tests is broken!
With JUnit4, everything was working perfectly! But after the migration, the plugin was always reporting that not tests are run:
'Tests run: 0, Failures: 0, Errors: 0, Skipped: 0 ...'!
Calculator Class
For the purpose of this blog, let us assume we want to build a Calculator. For now, we only have the ‘add‘ method implemented as shown below.
Calculator.java
public final class Calculator {
public static int add(int firstNumber, int secondNumber) {
return firstNumber + secondNumber;
}
}
JUnit 4 Code
I will start with the ‘JUnit 4’ version of the code.
pom.xml
We need to depend on the junit artifacts and add the plugin for the surefire. Here is the required pom file:
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.19.1</version>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
</dependencies>
CalculatorTest.java
In the test class, we have one test that asserts our method is doing the correct addition.
import org.junit.Assert;
import org.junit.Test;
public class CalculatorTest {
@Test
public void
our_calculator_should_add_2_numbers() {
Assert.assertEquals(5, Calculator.add(2, 3));
}
}
Build Output
Now, if we try to run ‘mvn clean install‘ on the above pom file we get the below output:
------------------------------------------------------- T E S T S ------------------------------------------------------- Running CalculatorTest Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.037 sec - in CalculatorTest Results : Tests run: 1, Failures: 0, Errors: 0, Skipped: 0 **** [INFO] -------------------------------------------------- [INFO] BUILD SUCCESS [INFO] --------------------------------------------------
Everything works perfectly!
JUnit 5 Code
It’s time to migrate our code to ‘JUnit 5’!
pom.xml
The first step is changing our dependencies in the pom file.
Some significant changes were applied to the ‘Junit 5’ dependency metadata. The framework functionalities have been split into several artifacts:
- junit-jupiter-api
- junit-jupiter-engine
- junit-platform-suite-api
- junit-jupiter-params
- junit-platform-surefire-provider
- …
For this simple example, it is enough to depend on ‘junit-jupiter-engine‘ & ‘junit-platform-surefire-provider‘.
So, our pom becomes:
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.19.1</version>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<version>5.0.0</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.platform</groupId>
<artifactId>junit-platform-surefire-provider</artifactId>
<version>1.0.0</version>
</dependency>
</dependencies>
P.S. Check ‘JUnit 5 User Guide‘ if you are interested in more details on the ‘JUnit 5’ artifacts
CalculatorTest.java
A good portion of the code in tests has to be changed to migrate to ‘JUnit 5’. Again, I am not going to cover those changes in this blog.
For the simple test we have written before, we need to change two things:
- Change the import statements
- Change the assertion call
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
public class CalculatorTest {
@Test
public void
our_calculator_should_add_2_numbers() {
Assertions.assertEquals(5, Calculator.add(2, 3));
}
}
Build Output
Although the ‘mvn clean install‘ command is still returning a ‘BUILD SUCCESS‘ message, it is actually not running any tests which make the whole build process suspicious.
This is our issue!
------------------------------------------------------- T E S T S ------------------------------------------------------- Running CalculatorTest Tests run: 0, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec - in CalculatorTest Results : Tests run: 0, Failures: 0, Errors: 0, Skipped: 0 **** [INFO] ------------------------------------------------ [INFO] BUILD SUCCESS [INFO] ------------------------------------------------
The Fix
The fix to this problem is simple, need to modify the build section in our pom to add the 2 dependencies to the ‘maven-surefire-plugin‘ plugin section as shown below.
By doing so, we forced the maven-surefire-plugin to use the latest JUnit artifacts and thus run the JUnit 5 tests.
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.19.1</version>
<dependencies>
<dependency>
<groupId>org.junit.platform</groupId>
<artifactId>junit-platform-surefire-provider</artifactId>
<version>1.0.0</version>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<version>5.0.0</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
Running ‘mvn clean install‘ will return the correct output now:
------------------------------------------------------- T E S T S ------------------------------------------------------- Running CalculatorTest Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.044 sec - in CalculatorTest Results : Tests run: 1, Failures: 0, Errors: 0, Skipped: 0 **** [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESS [INFO] ------------------------------------------------------------------------
I hope this blog post will save you some time when migrating to ‘JUnit 5’!
Good luck 🙂
AHMAD ATWI 