JUnit 5 @BeforeEach annotation is replacement of @Before
annotation in JUnit 4. It is used to signal that the annotated method should be executed before each @Test
method in the current class.
@BeforeEach Annotation Usage
Annotate a method with @BeforeEach
as given below:
@BeforeEach public void initEach(){ System.out.println("Before Each initEach() method called"); }
@BeforeEach
annotated method MUST NOT be a static method otherwise it will throw runtime error.
org.junit.platform.commons.JUnitException: @BeforeEach method 'public static void com.howtodoinjava.junit5.examples.JUnit5AnnotationsExample.initEach()' must not be static. at org.junit.jupiter.engine.descriptor.LifecycleMethodUtils.assertNonStatic(LifecycleMethodUtils.java:73) at org.junit.jupiter.engine.descriptor.LifecycleMethodUtils.lambda$findBeforeEachMethods$2(LifecycleMethodUtils.java:54) at java.util.ArrayList.forEach(ArrayList.java:1249) at java.util.Collections$UnmodifiableCollection.forEach(Collections.java:1080) at org.junit.jupiter.engine.descriptor.LifecycleMethodUtils.findBeforeEachMethods(LifecycleMethodUtils.java:54)
@BeforeEach Annotation Example
Let’s take an example. I have used one Calculator
class and added one add
method. I will test it 5 times using @RepeatedTest
annotation. This annotation will cause the add
test to run 5 times. For every run of test method, @BeforeEach
annotated method should also run every time.
package com.howtodoinjava.junit5.examples; import org.junit.jupiter.api.Assertions; import org.junit.jupiter.api.BeforeAll; import org.junit.jupiter.api.BeforeEach; import org.junit.jupiter.api.DisplayName; import org.junit.jupiter.api.RepeatedTest; import org.junit.jupiter.api.RepetitionInfo; import org.junit.jupiter.api.Test; import org.junit.jupiter.api.TestInfo; import org.junit.platform.runner.JUnitPlatform; import org.junit.runner.RunWith; @RunWith(JUnitPlatform.class) public class BeforeEachTest { @DisplayName("Add operation test") @RepeatedTest(5) void addNumber(TestInfo testInfo, RepetitionInfo repetitionInfo) { System.out.println("Running test -> " + repetitionInfo.getCurrentRepetition()); Assertions.assertEquals(2, Calculator.add(1, 1), "1 + 1 should equal 2"); } @BeforeAll public static void init(){ System.out.println("BeforeAll init() method called"); } @BeforeEach public void initEach(){ System.out.println("BeforeEach initEach() method called"); } }
Where Calculator class is:
package com.howtodoinjava.junit5.examples; public class Calculator { public int add(int a, int b) { return a + b; } }
Now execute the test and you will see below console output:
BeforeAll init() method called BeforeEach initEach() method called BeforeEach initEach() method called Running test -> 1 BeforeEach initEach() method called Running test -> 2 BeforeEach initEach() method called Running test -> 3 BeforeEach initEach() method called Running test -> 4 BeforeEach initEach() method called Running test -> 5
Clearly, @BeforeEach
annotated initEach()
method is called once per test method invocation.
Happy Learning !!