@MethodSource references a factory method that returns arguments for a @ParameterizedTest.

Java source and doc

Definition of MethodSource

package org.junit.jupiter.params.provider;
   ........
@Target({ElementType.ANNOTATION_TYPE, ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@Repeatable(MethodSources.class)
@API(status = STABLE, since = "5.7")
@ArgumentsSource(MethodArgumentsProvider.class)
@SuppressWarnings("exports")
public @interface MethodSource {
    String[] value() default ""; 1
}

Example

package com.logicbig.example;

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.Arguments;
import org.junit.jupiter.params.provider.MethodSource;

import java.util.stream.Stream;

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

public class ParameterizedMethodSourceTest {

    static Stream<String> palindromes() {
        return Stream.of("madam", "racecar", "level");
    }

    @ParameterizedTest
    @MethodSource("additionProvider")
    void testAddition(int a, int b, int expected) {
        assertEquals(expected, a + b);
    }

    @ParameterizedTest(name = "#{index} method source arg={0}")
    @MethodSource("palindromes")
    void isPalindromeFromMethodSource(String input) {
        assertTrue(new StringBuilder(input).reverse().toString().equals(input));
    }
    // Factory method must be static
    private static Stream<Arguments> additionProvider() {
        return Stream.of(
                Arguments.of(1, 2, 3),
                Arguments.of(0, 0, 0),
                Arguments.of(-5, 5, 0),
                Arguments.of(100, 200, 300)
        );
    }
}

mvn test -Dtest=ParameterizedMethodSourceTest

Output

D:\example-projects\junit-5\junit-5-parameterized-tests\junit-5-parameterized-methodsource>mvn test -Dtest=ParameterizedMethodSourceTest
[INFO] Scanning for projects...
[INFO] 
[INFO] -------< com.logicbig.example:junit-5-parameterized-methodsource >-------
[INFO] Building junit-5-parameterized-methodsource 1.0-SNAPSHOT
[INFO]   from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- resources:3.3.1:resources (default-resources) @ junit-5-parameterized-methodsource ---
[INFO] skip non existing resourceDirectory D:\example-projects\junit-5\junit-5-enabling-disabling-tests\junit-5-parameterized-tests\junit-5-parameterized-methodsource\src\main\resources
[INFO] 
[INFO] --- compiler:3.14.1:compile (default-compile) @ junit-5-parameterized-methodsource ---
[INFO] No sources to compile
[INFO] 
[INFO] --- resources:3.3.1:testResources (default-testResources) @ junit-5-parameterized-methodsource ---
[INFO] skip non existing resourceDirectory D:\example-projects\junit-5\junit-5-enabling-disabling-tests\junit-5-parameterized-tests\junit-5-parameterized-methodsource\src\test\resources
[INFO] 
[INFO] --- compiler:3.14.1:testCompile (default-testCompile) @ junit-5-parameterized-methodsource ---
[INFO] Nothing to compile - all classes are up to date.
[INFO] 
[INFO] --- surefire:3.5.0:test (default-test) @ junit-5-parameterized-methodsource ---
[INFO] Using auto detected provider org.apache.maven.surefire.junitplatform.JUnitPlatformProvider
[INFO] 
[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] +--com.logicbig.example.ParameterizedMethodSourceTest - 0.276 ss
[INFO] |  +-- [OK] testAddition(int, int, int)[1] 1, 2, 3 - 0.073 ss
[INFO] |  +-- [OK] testAddition(int, int, int)[2] 0, 0, 0 - 0.003 ss
[INFO] |  +-- [OK] testAddition(int, int, int)[3] -5, 5, 0 - 0.002 ss
[INFO] |  +-- [OK] testAddition(int, int, int)[4] 100, 200, 300 - 0.005 ss
[INFO] |  +-- [OK] isPalindromeFromMethodSource(String) #1 method source arg="madam" - 0.008 ss
[INFO] |  +-- [OK] isPalindromeFromMethodSource(String) #2 method source arg="racecar" - 0.001 ss
[INFO] |  '-- [OK] isPalindromeFromMethodSource(String) #3 method source arg="level" - 0.003 ss
[INFO] 
[INFO] Results:
[INFO] 
[INFO] Tests run: 7, Failures: 0, Errors: 0, Skipped: 0
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  5.710 s
[INFO] Finished at: 2025-12-04T14:06:10+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