Java Unit Testing with JUnit 5/

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assertFalse method

assertFalse method

This lesson demonstrates how to use assertFalse method in JUnit 5 to assert test conditions.

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assertFalse() method

Assertions API provide static assertFalse() method. This method helps us in validating that the actual value supplied to it is false.

  • If the actual value is false then test case will pass.
  • If the actual value is true then test case will fail.

There are basically six useful overloaded methods for assertFalse -

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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)
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assertFalse() method

Demo

Let’s look into the usage of the above methods.

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JUnit5 (Java 1.8)
package io.educative.junit5;
import static org.junit.jupiter.api.Assertions.assertFalse;
import org.junit.jupiter.api.Test;
public class AssertFalseDemo {
	@Test
	public void testAssertFalseWithFalseCondition() {
		boolean falseValue = false;
		assertFalse(falseValue);
	}
	
	@Test
	public void testAssertFalseWithTrueCondition() {
		boolean trueValue = true;
		assertFalse(trueValue);
	}
	
	@Test
	public void testAssertFalseWithTrueConditionAndMessage() {
		boolean trueValue = true;
		assertFalse(trueValue, "The actual value is true");
	}
	
	@Test
	public void testAssertFalseWithTrueConditionAndMessageSupplier() {
		boolean trueValue = true;
		assertFalse(trueValue, () -> "The actual value is true");
	}
	
	@Test
	public void testAssertFalseWithBooleanSupplier() {
		boolean falseValue = false;
		assertFalse(() -> falseValue);
	}
	
	@Test
	public void testAssertFalseWithBooleanSupplierAndMessage() {
		boolean trueValue = true;
		assertFalse(() -> trueValue, "The actual value is true");
	}
	
	@Test
	public void testAssertFalseWithBooleanSupplierAndMessageSupplier() {
		boolean trueValue = true;
		assertFalse(() -> trueValue, () -> "The actual value is true");
	}
}

You can perform code changes to above code widget, run and practice different outcomes.

Run AssertFalseDemo class as JUnit Test.

widget

Explanation -

In AssertFalseDemo class, there are 7 @Test methods. These 7 methods demonstrate the working of the above 6 overloaded methods of ...