java assert test code example

Example 1: java testing with assertions

import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;

public class AssertionExample {

    /**
     * The assertionExample function
     * uses multiple assertions for the purpose of example;
     * Usually in one method it is recommended to have 1 assertion;
     */
    @Test
    public void assertionExample()
    {
        Assertions.assertEquals(2+2,4);

        Assertions.assertNotEquals(6+3,10);

        Assertions.assertTrue("Radu".length()==4);

        String tester = null;

        Assertions.assertThrows(NullPointerException.class,()->tester.equals("emptyString"));
    }
}

Example 2: java junit test

import org.junit.Assert;
import org.junit.Test;

public class Test {

    public static int square(int n) {
        return n * n;
    }

    @Test
    public void squareTest() {
        Assert.assertEquals(25, square(5));
        Assert.assertEquals(16, square(4));
        Assert.assertEquals(9, square(3));
        Assert.assertEquals(4, square(2));
        Assert.assertEquals(1, square(1));
    }
}