JUnit 5 does not execute method annotated with BeforeEach

Question

JUnit 5 does not invoke my method in a test class that is annotated with the @BeforeEach annotation, where I initialize some fields of the test object that are needed in the tests. When trying to access these fields inside a test method (method annotated with @Test) I obviously get a NullpointerException. So I added some output messages to the methods.

import static org.junit.jupiter.api.Assertions.assertEquals;

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

public class TestClass {
   private String s;

   public TestClass() {

   }

   @BeforeEach
   public void init() {
      System.out.println("before");
      s = "not null";
   }

   @Test
   public void test0() {
      System.out.println("testing");
      assertEquals("not null", s.toString());
   }

}

In the output of the tests when running mvn clean test I get the "testing" message from the test0() method annotated with @Test annotation, but the "before" message is not printed.

Running de.dk.spielwiese.TestClass
!!!testing!!!
Tests run: 1, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 0 sec <<< FAILURE!
de.dk.spielwiese.TestClass.test0()  Time elapsed: 0 sec  <<< FAILURE!
java.lang.NullPointerException
        at de.dk.spielwiese.TestClass.test0(TestClass.java:24)

The very obvious and only reason that I can think of is that the init() method is not invoked. The documentation of @BeforeEach says

@BeforeEach is used to signal that the annotated method should be executed before each @Test, @RepeatedTest, @ParameterizedTest, @TestFactory, and @TestTemplate method in the current test class.

I also tried running the tests in eclipse and there they always pass without any errors.

I am using maven 3.5.3. I declared JUnit Jupiter 5.1.0 as dependency in my pom.xml

<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>de.dk</groupId>
<artifactId>spielwiese</artifactId>
<version>0-SNAPSHOT</version>
<packaging>jar</packaging>

<name>Spielwiese</name>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<build>
    <plugins>
        <plugin>
            <artifactId>maven-assembly-plugin</artifactId>
            <version>3.0.0</version>
            <configuration>
                <archive>
                    <manifest>
                        <mainClass>de.dk.spielwiese.Spielwiese</mainClass>
                    </manifest>
                </archive>
                <descriptorRefs>
                    <descriptorRef>jar-with-dependencies</descriptorRef>
                </descriptorRefs>
                <appendAssemblyId>false</appendAssemblyId>
                <finalName>Spielwiese</finalName>
            </configuration>
            <executions>
                <execution>
                    <id>assemble-all</id>
                    <phase>package</phase>
                    <goals>
                        <goal>single</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
        <plugin>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.6.2</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
            </configuration>
        </plugin>
        <plugin>
            <artifactId>maven-jar-plugin</artifactId>
            <version>3.0.2</version>
        </plugin>
    </plugins>
</build>

<dependencies>
    <dependency>
        <groupId>de.dk</groupId>
        <artifactId>util</artifactId>
        <version>0.0.1</version>
    </dependency>
    <dependency>
        <groupId>org.junit.jupiter</groupId>
        <artifactId>junit-jupiter-engine</artifactId>
        <version>5.1.0</version>
        <scope>test</scope>
    </dependency>
</dependencies>

Why is my init() method not invoked?

Answer 1

In my case the problem was that the @Test annotation was taken from wrong import. Originally it was imported from org.junit.Test. Once I have switched it to org.junit.jupiter.api.Test the problem was resolved.

Wrong original code:

import org.junit.Test;

@BeforeEach
...some code

@Test
...some code

Correct fixed code:

import org.junit.jupiter.api.Test;

@BeforeEach
...some code

@Test
...some code