Junit: Assertions

'org.junit.Assert' class provides number of assertion methods to verify the expected values. Assert class uses hamcrest library internally. If you would like to know about hamcrest library, I would recommend you go through my below tutorial series.

https://self-learning-java-tutorial.blogspot.com/2018/02/hamcrest-tutorial.html

The format of all assertions looks like below.

assertionMethod(expectedValue, actualValue)

assertionMethod(message, expectedValue, actualValue)

‘message’ will be displayed on failures.

Let’s see it by an example.

To demonstrate this example, I implemented add method wrongly.

Arithmetic.java

package com.sample.arithmetic;

public class Arithmetic {

 public int add(int a, int b) {
  return a + b + b;
 }

}

ArithmeticTest.java

package com.sample.arithmetic;

import static org.junit.Assert.assertEquals;

import org.junit.Test;

/**
 * Test cases follow below naming convention. methodName_input_output format.
 * 
 * @author krishna
 *
 */
public class ArithmeticTest {

 @Test
 public void divide_10Plus7_17() {

  Arithmetic obj1 = new Arithmetic();

  int actual = obj1.add(10, 7);
  int expected = 17;

  assertEquals("Addition of 10, 7 is failing", expected, actual);

 }
}

When I ran, ArithmeticTest.java, I can able to see the error message.

In my next posts, I will explain all the assert methods in detail.

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