MathStuff.java

public class MathStuff {

    public int timesTwo(int n) {
        if (n >= Integer.MAX_VALUE)
            throw new IllegalArgumentException("Value can't be bigger than" + Integer.MAX_VALUE/2);
        if (n <= Integer.MIN_VALUE)
            throw new IllegalArgumentException("Value can't be less than" + Integer.MIN_VALUE/2);

        int product = 2 * n;
        return product;
    }
}

MathStuffTest

public class MathStuffTest {

    MathStuff stuff;

    @Before
    public void setUp() throws Exception {
        stuff = new MathStuff();
    }

    @After
    public void tearDown() throws Exception {
    }

    @Test
    public void twoTimesTwo() {
        int result = stuff.timesTwo(2);
        assertEquals(4,result);
    }

    @Test
    public void zeroTimesTwo() {
        int result = stuff.timesTwo(0);
        assertEquals(0,result);
    }

    @Test
    public void negTwentyTimesTwo() {
        int result = stuff.timesTwo(-20);
        assertEquals(-40,result);
    }

    @Test
    public void wayBigTimesTwo() {
        try {
            stuff.timesTwo(Integer.MAX_VALUE);
        } catch (IllegalArgumentException iae) {
            System.out.println("Success");
        } catch (Exception e) {
            fail("Test Failed!");
        }

    }

    @Test
    public void wayNegativeTimesTwo() {
        try {
            stuff.timesTwo(Integer.MAX_VALUE);
        } catch (IllegalArgumentException iae) {
            //System.out.println("Success");
        } catch (Exception e) {
            fail("Test Failed!");
        }
    }

@Test
public void wayNegativeTimesTwo() {
    boolean caught = false;
    try {
        stuff.timesTwo(Integer.MAX_VALUE);
    } catch (IllegalArgumentException iae) {
        caught = true;
    }
    if (!caught)
        fail("Test Failed!");
}


}