Use targeted methods instead of LINQ

fluentassertions · Oct 12, 2023 · 1ff6be6 · 1ff6be6
1 parent 3f250d8
commit 1ff6be6
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Showing 3 changed files with 27 additions and 5 deletions.
diff --git a/Src/FluentAssertions/Common/TypeExtensions.cs b/Src/FluentAssertions/Common/TypeExtensions.cs
@@ -351,9 +351,7 @@ private static bool IsImplementationOfOpenGeneric(this Type type, Type definitio
 
         // check subject's interfaces against definition
         return type.GetInterfaces()
-            .Where(i => i.IsGenericType)
-            .Select(i => i.GetGenericTypeDefinition())
-            .Contains(definition);
+            .Any(i => i.IsGenericType && i.GetGenericTypeDefinition() == definition);
     }
 
     public static bool IsDerivedFromOpenGeneric(this Type type, Type definition)

diff --git a/Src/FluentAssertions/Types/TypeAssertions.cs b/Src/FluentAssertions/Types/TypeAssertions.cs
@@ -462,7 +462,7 @@ public AndConstraint<TypeAssertions> Implement(Type interfaceType, string becaus
     {
         Guard.ThrowIfArgumentIsNull(interfaceType);
 
-        bool containsInterface = Subject.GetInterfaces().Contains(interfaceType);
+        bool containsInterface = interfaceType.IsAssignableFrom(Subject) && interfaceType != Subject;
 
         Execute.Assertion
             .BecauseOf(because, becauseArgs)
@@ -511,7 +511,7 @@ public AndConstraint<TypeAssertions> NotImplement(Type interfaceType, string bec
     {
         Guard.ThrowIfArgumentIsNull(interfaceType);
 
-        bool containsInterface = Subject.GetInterfaces().Contains(interfaceType);
+        bool containsInterface = interfaceType.IsAssignableFrom(Subject) && interfaceType != Subject;
 
         Execute.Assertion
             .BecauseOf(because, becauseArgs)

diff --git a/Tests/FluentAssertions.Specs/Types/TypeAssertionSpecs.Implement.cs b/Tests/FluentAssertions.Specs/Types/TypeAssertionSpecs.Implement.cs
@@ -73,6 +73,20 @@ public void When_asserting_a_type_to_implement_null_it_should_throw()
             act.Should().ThrowExactly<ArgumentNullException>()
                 .WithParameterName("interfaceType");
         }
+
+        [Fact]
+        public void An_interface_does_not_implement_itself()
+        {
+            // Arrange
+            var type = typeof(IDummyInterface);
+
+            // Act
+            Action act = () =>
+                type.Should().Implement(typeof(IDummyInterface));
+
+            // Assert
+            act.Should().Throw<XunitException>();
+        }
     }
 
     public class ImplementOfT
@@ -156,6 +170,16 @@ public void When_asserting_a_type_not_to_implement_null_it_should_throw()
             act.Should().ThrowExactly<ArgumentNullException>()
                 .WithParameterName("interfaceType");
         }
+
+        [Fact]
+        public void An_interface_does_not_implement_itself()
+        {
+            // Arrange
+            var type = typeof(IDummyInterface);
+
+            // Act / Assert
+            type.Should().NotImplement(typeof(IDummyInterface));
+        }
     }
 
     public class NotImplementOfT