public void Test_to_fahrenheit_from_celsius_with_invalid_parameter_throws_exception(int input)
        {
            // Arrange.
            var inputCelsius = new CelsiusInt(input);

            // Act.
            var result = Assert.Throws <ArgumentOutOfRangeException>(() => inputCelsius.ToFahrenheit());

            // Assert.
            result.Message.Should().Contain("Value out of range for type.");
        }
        public void Test_to_fahrenheit_from_celsius_returns_correct_value()
        {
            // Arrange.
            const int expected = 54;
            var       input    = new CelsiusInt(12);

            // Act.
            var result = input.ToFahrenheit();

            // Assert.
            result.Should().Be(expected);
        }