@NullSource provides a single null value to a @ParameterizedTest.

Java source and doc

Definition of NullSource

package org.junit.jupiter.params.provider;
   ........
@Target({ElementType.ANNOTATION_TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@API(status = STABLE, since = "5.7")
@ArgumentsSource(NullArgumentsProvider.class)
public @interface NullSource {}

Example Project

package com.logicbig.example;

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.NullSource;

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

public class ParameterizedNullSourceTest {

    @ParameterizedTest(name = "#{index} null argument should be provided")
    @NullSource
    void receivesNull(String input) {
        assertNull(input);
    }
}

mvn test -Dtest=ParameterizedNullSourceTest

Output

D:\example-projects\junit-5\junit-5-parameterized-tests\junit-5-parameterized-nullsource>mvn test -Dtest=ParameterizedNullSourceTest
[INFO] Scanning for projects...
[INFO] 
[INFO] -------< com.logicbig.example:junit-5-parameterized-nullsource >--------
[INFO] Building junit-5-parameterized-nullsource 1.0-SNAPSHOT
[INFO]   from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- resources:3.3.1:resources (default-resources) @ junit-5-parameterized-nullsource ---
[INFO] skip non existing resourceDirectory D:\example-projects\junit-5\junit-5-parameterized-tests\junit-5-parameterized-nullsource\src\main\resources
[INFO] 
[INFO] --- compiler:3.14.1:compile (default-compile) @ junit-5-parameterized-nullsource ---
[INFO] No sources to compile
[INFO] 
[INFO] --- resources:3.3.1:testResources (default-testResources) @ junit-5-parameterized-nullsource ---
[INFO] skip non existing resourceDirectory D:\example-projects\junit-5\junit-5-parameterized-tests\junit-5-parameterized-nullsource\src\test\resources
[INFO] 
[INFO] --- compiler:3.14.1:testCompile (default-testCompile) @ junit-5-parameterized-nullsource ---
[INFO] Recompiling the module because of changed source code.
[INFO] Compiling 1 source file with javac [debug target 25] to target\test-classes
[INFO] 
[INFO] --- surefire:3.5.0:test (default-test) @ junit-5-parameterized-nullsource ---
[INFO] Using auto detected provider org.apache.maven.surefire.junitplatform.JUnitPlatformProvider
[INFO] 
[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] +--com.logicbig.example.ParameterizedNullSourceTest - 0.125 ss
[INFO] |  '-- [OK] receivesNull(String) #1 null argument should be provided - 0.037 ss
[INFO] 
[INFO] Results:
[INFO] 
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  3.972 s
[INFO] Finished at: 2025-12-04T15:29:33+08:00
[INFO] ------------------------------------------------------------------------

Example Project

Dependencies and Technologies Used:

• junit-jupiter-engine 6.0.1 (Module "junit-jupiter-engine" of JUnit)
   Version Compatibility: 5.0.0 - 6.0.1Version List
  ×

  Version compatibilities of junit-jupiter-engine with this example:

  • 5.0.0
  • 5.0.1
  • 5.0.2
  • 5.0.3
  • 5.1.0
  • 5.1.1
  • 5.2.0
  • 5.3.0
  • 5.3.1
  • 5.3.2
  • 5.4.0
  • 5.4.1
  • 5.4.2
  • 5.5.0
  • 5.5.1
  • 5.5.2
  • 5.6.0
  • 5.6.1
  • 5.6.2
  • 5.6.3
  • 5.7.0
  • 5.7.1
  • 5.7.2
  • 5.8.0
  • 5.8.1
  • 5.8.2
  • 5.9.0
  • 5.9.1
  • 5.9.2
  • 5.9.3
  • 5.10.0
  • 5.10.1
  • 5.10.2
  • 5.10.3
  • 5.10.4
  • 5.10.5
  • 5.11.0
  • 5.11.1
  • 5.11.2
  • 5.11.3
  • 5.11.4
  • 5.12.0
  • 5.12.1
  • 5.12.2
  • 5.13.0
  • 5.13.1
  • 5.13.2
  • 5.13.3
  • 5.13.4
  • 5.14.0
  • 5.14.1
  • 6.0.0
  • 6.0.1

  Versions in green have been tested.

• junit-jupiter-params 6.0.1 (Module "junit-jupiter-params" of JUnit)
  
• JDK 25
• Maven 3.9.11