Following methods assert that the given boolean condition is true or false.

public static void assertTrue(boolean condition)
public static void assertTrue(boolean condition, Supplier<String> messageSupplier)
public static void assertTrue(BooleanSupplier booleanSupplier)
public static void assertTrue(BooleanSupplier booleanSupplier, String message)
public static void assertTrue(boolean condition, String message)
public static void assertTrue(BooleanSupplier booleanSupplier, Supplier<String> messageSupplier)
public static void assertFalse(boolean condition)
public static void assertFalse(boolean condition, String message)
public static void assertFalse(boolean condition, Supplier<String> messageSupplier)
public static void assertFalse(BooleanSupplier booleanSupplier)
public static void assertFalse(BooleanSupplier booleanSupplier, String message)
public static void assertFalse(BooleanSupplier booleanSupplier, Supplier<String> messageSupplier)

Example

package com.logicbig.example;

import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assertions.assertFalse;

public class TrueFalseExamples {

  @Test
  void testBasicConditions() {
      int number = 10;

      assertTrue(number > 5);
      assertTrue(number == 10);
      assertFalse(number < 5);
      assertFalse(number == 15);
  }

  @Test
  void testStringOperations() {
      String name = "John Doe";

      assertTrue(name.startsWith("John"));
      assertTrue(name.contains("Doe"));
      assertFalse(name.isEmpty());
      assertFalse(name.endsWith("Smith"));
  }

  @Test
  void testListOperations() {
      java.util.List<String> fruits = new java.util.ArrayList<>();
      fruits.add("apple");
      fruits.add("banana");

      assertTrue(fruits.contains("apple"));
      assertTrue(fruits.size() == 2);
      assertFalse(fruits.contains("orange"));
      assertFalse(fruits.isEmpty());
  }
}

mvn test -Dtest=TrueFalseExamples

Output

D:\example-projects\junit-5\junit-5-assertions\junit-5-asserting-boolean-conditions>mvn test -Dtest=TrueFalseExamples
[INFO] Scanning for projects...
[INFO] 
[INFO] -----< com.logicbig.example:junit-5-asserting-boolean-conditions >------
[INFO] Building junit-5-asserting-boolean-conditions 1.0-SNAPSHOT
[INFO]   from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- resources:3.3.1:resources (default-resources) @ junit-5-asserting-boolean-conditions ---
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] skip non existing resourceDirectory D:\example-projects\junit-5\junit-5-assertions\junit-5-asserting-boolean-conditions\src\main\resources
[INFO] 
[INFO] --- compiler:3.14.1:compile (default-compile) @ junit-5-asserting-boolean-conditions ---
[INFO] Nothing to compile - all classes are up to date.
[INFO] 
[INFO] --- resources:3.3.1:testResources (default-testResources) @ junit-5-asserting-boolean-conditions ---
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] skip non existing resourceDirectory D:\example-projects\junit-5\junit-5-assertions\junit-5-asserting-boolean-conditions\src\test\resources
[INFO] 
[INFO] --- compiler:3.14.1:testCompile (default-testCompile) @ junit-5-asserting-boolean-conditions ---
[INFO] Recompiling the module because of added or removed source files.
[INFO] Compiling 1 source file with javac [debug target 25] to target\test-classes
[INFO] 
[INFO] --- surefire:3.2.5:test (default-test) @ junit-5-asserting-boolean-conditions ---
[INFO] Using auto detected provider org.apache.maven.surefire.junitplatform.JUnitPlatformProvider
[INFO] 
[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running com.logicbig.example.TrueFalseExamples
[INFO] Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.042 s -- in com.logicbig.example.TrueFalseExamples
[INFO] 
[INFO] Results:
[INFO] 
[INFO] Tests run: 3, Failures: 0, Errors: 0, Skipped: 0
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  3.224 s
[INFO] Finished at: 2025-12-01T11:42:24+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.

• JDK 25
• Maven 3.9.11