Add support to convert into to enum

Author: aldelaro5

Src/FluentAssertions/Equivalency/Steps/AutoConversionStep.cs

@@ -56,6 +56,18 @@ private static bool TryChangeType(object subject, Type expectationType, out obje
 
         try
         {
+            if (expectationType.IsEnum)
+            {
+                if (Enum.IsDefined(expectationType, subject))
+                {
+                    subject = Enum.ToObject(expectationType, subject);
+                }
+                else
+                {
+                    return false;
+                }
+            }
+
             conversionResult = Convert.ChangeType(subject, expectationType, CultureInfo.InvariantCulture);
             return true;
         }

Tests/FluentAssertions.Equivalency.Specs/MemberConversionSpecs.cs

@@ -51,6 +51,32 @@ public void When_an_int_is_compared_equivalent_to_a_string_representing_the_numb
         act.Should().NotThrow();
     }
 
+    [Fact]
+    public void Numbers_can_be_converted_to_enums()
+    {
+        // Arrange
+        var expectation = new { Property = EnumFour.Three };
+        var subject = new { Property = 3 };
+
+        // Act / Assert
+        subject.Should().BeEquivalentTo(expectation, options => options.WithAutoConversion());
+    }
+
+    [Fact]
+    public void Numbers_that_are_out_of_range_cannot_be_converted_to_enums()
+    {
+        // Arrange
+        var expectation = new { Property = EnumFour.Three };
+        var subject = new { Property = 4 };
+
+        // Act
+        Action act = () => subject.Should().BeEquivalentTo(expectation, options => options.WithAutoConversion());
+
+        // Assert
+        act.Should().Throw<XunitException>()
+            .WithMessage("*subject*Property*EnumFour*");
+    }
+
     [Fact]
     public void When_injecting_a_null_predicate_into_WithAutoConversionFor_it_should_throw()
     {