NotBeApproximately double version accepting nullable subject and expe…

…cted
fluentassertions · Oct 7, 2018 · e855ab7 · e855ab7
1 parent f9c638f
commit e855ab7
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diff --git a/Src/FluentAssertions/NumericAssertionsExtensions.cs b/Src/FluentAssertions/NumericAssertionsExtensions.cs
@@ -1100,6 +1100,47 @@ public static class NumericAssertionsExtensions
             return new AndConstraint<NullableNumericAssertions<double>>(parent);
         }
 
+        /// <summary>
+        /// Asserts a double value does not approximate another value by a given amount.
+        /// Does not throw if null subject value approximates null <paramref name="unexpectedValue"/> value.
+        /// </summary>
+        /// <param name="parent">The <see cref="NumericAssertions{T}"/> object that is being extended.</param>
+        /// <param name="unexpectedValue">
+        /// The unexpected value to compare the actual value with.
+        /// </param>
+        /// <param name="precision">
+        /// The minimum exclusive amount of which the two values should differ.
+        /// </param>
+        /// <param name="because">
+        /// A formatted phrase as is supported by <see cref="string.Format(string,object[])"/> explaining why the assertion
+        /// is needed. If the phrase does not start with the word <i>because</i>, it is prepended automatically.
+        /// </param>
+        /// <param name="becauseArgs">
+        /// Zero or more objects to format using the placeholders in <see cref="because"/>.
+        /// </param>
+        public static AndConstraint<NullableNumericAssertions<double>> NotBeApproximately(this NullableNumericAssertions<double> parent,
+            double? unexpectedValue, double precision, string because = "",
+            params object[] becauseArgs)
+        {
+            if (parent.Subject == null && unexpectedValue == null)
+            {
+                return new AndConstraint<NullableNumericAssertions<double>>(parent);
+            }
+
+            bool succeeded = Execute.Assertion
+                .ForCondition(unexpectedValue != null)
+                .BecauseOf(because, becauseArgs)
+                .FailWith("Expected {context:value} to not approximate {0} +/- {1}{reason}, but it was {2}.", unexpectedValue, precision, parent.Subject);
+
+            if (succeeded)
+            {
+                // ReSharper disable once PossibleInvalidOperationException
+                parent.NotBeApproximately(unexpectedValue.Value, precision, because, becauseArgs);
+            }
+
+            return new AndConstraint<NullableNumericAssertions<double>>(parent);
+        }
+
         /// <summary>
         /// Asserts a double value does not approximate another value by a given amount.
         /// </summary>

diff --git a/Tests/Shared.Specs/NullableNumericAssertionSpecs.cs b/Tests/Shared.Specs/NullableNumericAssertionSpecs.cs
@@ -824,6 +824,107 @@ public void When_asserting_not_approximately_and_nullable_double_is_indeed_appro
                 .WithMessage("Expected value to not approximate 3.14 +/- 0.1, but 3.14*only differed by*");
         }
 
+        [Fact]
+        public void When_asserting_not_approximately_and_nullable_double_is_not_approximating_a_nullable_value_it_should_not_throw()
+        {
+            //-----------------------------------------------------------------------------------------------------------
+            // Arrange
+            //-----------------------------------------------------------------------------------------------------------
+            double? value = 3.1415927F;
+            double? expected = 1.0F;
+
+            //-----------------------------------------------------------------------------------------------------------
+            // Act
+            //-----------------------------------------------------------------------------------------------------------
+            Action act = () => value.Should().NotBeApproximately(expected, 0.1F);
+
+            //-----------------------------------------------------------------------------------------------------------
+            // Assert
+            //-----------------------------------------------------------------------------------------------------------
+            act.Should().NotThrow();
+        }
+
+        [Fact]
+        public void When_asserting_not_approximately_and_nullable_double_is_not_approximating_a_null_value_it_should_throw()
+        {
+            //-----------------------------------------------------------------------------------------------------------
+            // Arrange
+            //-----------------------------------------------------------------------------------------------------------
+            double? value = 3.1415927F;
+            double? expected = null;
+
+            //-----------------------------------------------------------------------------------------------------------
+            // Act
+            //-----------------------------------------------------------------------------------------------------------
+            Action act = () => value.Should().NotBeApproximately(expected, 0.1F);
+
+            //-----------------------------------------------------------------------------------------------------------
+            // Assert
+            //-----------------------------------------------------------------------------------------------------------
+            act.Should().Throw<XunitException>().WithMessage(
+                "Expected value to not approximate*<null>* +/-*0.1*, but it was 3.14*");
+        }
+
+        [Fact]
+        public void When_asserting_not_approximately_and_null_double_is_not_approximating_a_nullable_double_value_it_should_throw()
+        {
+            //-----------------------------------------------------------------------------------------------------------
+            // Arrange
+            //-----------------------------------------------------------------------------------------------------------
+            double? value = null;
+            double? expected = 20.0f;
+
+            //-----------------------------------------------------------------------------------------------------------
+            // Act
+            //-----------------------------------------------------------------------------------------------------------
+            Action act = () => value.Should().NotBeApproximately(expected, 0.1F);
+
+            //-----------------------------------------------------------------------------------------------------------
+            // Assert
+            //-----------------------------------------------------------------------------------------------------------
+            act.Should().Throw<XunitException>();
+        }
+
+        [Fact]
+        public void When_asserting_not_approximately_and_null_double_is_not_approximating_a_null_value_it_should_not_throw()
+        {
+            //-----------------------------------------------------------------------------------------------------------
+            // Arrange
+            //-----------------------------------------------------------------------------------------------------------
+            double? value = null;
+            double? expected = null;
+
+            //-----------------------------------------------------------------------------------------------------------
+            // Act
+            //-----------------------------------------------------------------------------------------------------------
+            Action act = () => value.Should().NotBeApproximately(expected, 0.1F);
+
+            //-----------------------------------------------------------------------------------------------------------
+            // Assert
+            //-----------------------------------------------------------------------------------------------------------
+            act.Should().NotThrow();
+        }
+
+        [Fact]
+        public void When_asserting_not_approximately_and_nullable_double_is_approximating_a_nullable_value_it_should_throw()
+        {
+            //-----------------------------------------------------------------------------------------------------------
+            // Arrange
+            //-----------------------------------------------------------------------------------------------------------
+            double? value = 3.1415927F;
+            double? expected = 3.1F;
+
+            //-----------------------------------------------------------------------------------------------------------
+            // Act
+            //-----------------------------------------------------------------------------------------------------------
+            Action act = () => value.Should().NotBeApproximately(expected, 0.1F);
+
+            //-----------------------------------------------------------------------------------------------------------
+            // Assert
+            //-----------------------------------------------------------------------------------------------------------
+            act.Should().Throw<XunitException>();
+        }
+
         [Fact]
         public void When_asserting_not_approximately_and_nullable_float_is_not_approximating_a_value_it_should_not_throw()
         {