public void ckeckdiv()
{
int a = 4;
int b = 4;
int expected = a / b;
int actual = obj.div(a, b);
Assert.AreEqual(actual, expected, 0, "Result is wrong");
int a1 = 4;
int b1 = 0;
Assert.ThrowsException <System.DivideByZeroException>(() => obj.div(a1, b1));
}