public void TestMultipleOfReturn() { var mathsHelper = new MathsHelper(); var number1 = 3; var number2 = 4; var number3 = 5; var number4 = 15; var result1 = mathsHelper.MultipleOf3or5orBoth(number1); var result2 = mathsHelper.MultipleOf3or5orBoth(number2); var result3 = mathsHelper.MultipleOf3or5orBoth(number3); var result4 = mathsHelper.MultipleOf3or5orBoth(number4); Assert.Equal(3, result1); Assert.Equal(0, result2); Assert.Equal(5, result3); Assert.Equal(15, result4); }