public void ValidateNullableDoubleToBeApproximatelyValue()
        {
            // Given
            var validator = new NullableDoubleInverseValidator(null);

            // When
            validator.BeApproximately(42, 0.1);

            // Then
            Assert.True(true);
        }
        public void ValidateDoubleToBeApproximatelyValueViolated()
        {
            // Given
            var validator = new NullableDoubleInverseValidator(42.12345);

            // When
            var exception = Assert.Throws <XunitException>(() => validator.BeApproximately(42.12, 0.01, "that's the bottom line"));

            // Then
            Assert.NotNull(exception);
            var rn = Environment.NewLine;

            Assert.Equal(
                $"{rn}validator{rn}is \"42,12345\"{rn}but was expected to be approximately \"42,12\" (+/- 0,01){rn}because that's the bottom line",
                exception.UserMessage);
        }