Editing Unit testing (section)

=== JUnit ===
Below is an example of a JUnit test suite. It focuses on the {{code|Adder}} class.

<syntaxhighlight lang="java">
class Adder {
    public int add(int a, int b) {
        return a + b;
    }
}
</syntaxhighlight>

The test suite uses [[Assertion (computing)|assert]] statements to verify the expected result of various input values to the {{code|sum}} method.

<syntaxhighlight lang="java">
import static org.junit.Assert.assertEquals;
import org.junit.Test;
public class AdderUnitTest {
    @Test
    public void sumReturnsZeroForZeroInput() {
        Adder adder = new Adder();
        assertEquals(0, adder.add(0, 0));
    }

    @Test
    public void sumReturnsSumOfTwoPositiveNumbers() {
        Adder adder = new Adder();
        assertEquals(3, adder.add(1, 2));
    }

    @Test
    public void sumReturnsSumOfTwoNegativeNumbers() {
        Adder adder = new Adder();
        assertEquals(-3, adder.add(-1, -2));
    }

    @Test
    public void sumReturnsSumOfLargeNumbers() {
        Adder adder = new Adder();
        assertEquals(2222, adder.add(1234, 988));
    }
}
</syntaxhighlight>