Java Unit Testing with JUnit 5/

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assertTrue() method

assertTrue() method

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

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assertTrue() method

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

  • If the actual value is true then test case will pass.
  • If the actual value is not true then test case will fail.

There are basically six useful overloaded methods for assertTrue:-

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public static void assertTrue(boolean condition)
  
public static void assertTrue(boolean condition, String message)
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(BooleanSupplier booleanSupplier, Supplier<String> messageSupplier)
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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.assertTrue;
import org.junit.jupiter.api.Test;
public class AssertTrueDemo {
	@Test
	public void testAssertTrueWithTrueCondition() {
		boolean trueValue = true;
		assertTrue(trueValue);
	}
	
	@Test
	public void testAssertTrueWithFalseCondition() {
		boolean falseValue = false;
		assertTrue(falseValue);
	}
	
	@Test
	public void testAssertTrueWithFalseConditionAndMessage() {
		boolean falseValue = false;
		assertTrue(falseValue, "The actual value is false");
	}
	
	@Test
	public void testAssertTrueWithFalseConditionAndMessageSupplier() {
		boolean falseValue = false;
		assertTrue(falseValue, () -> "The actual value is false");
	}
	
	@Test
	public void testAssertTrueWithBooleanSupplier() {
		boolean trueValue = true;
		assertTrue(() -> trueValue);
	}
	
	@Test
	public void testAssertTrueWithBooleanSupplierAndMessage() {
		boolean falseValue = false;
		assertTrue(() -> falseValue, "The actual value is false");
	}
	
	@Test
	public void testAssertTrueWithBooleanSupplierAndMessageSupplier() {
		boolean falseValue = false;
		assertTrue(() -> falseValue, () -> "The actual value is false");
	}
}

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

Run AssertTrueDemo class as JUnit Test.

widget

Explanation -

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