feat: add "Implements" filter and requirement

Source/Testably.Architecture.Rules/Extensions/TypeExtensions.cs

@@ -68,6 +68,45 @@ public static bool HasMethodWithAttribute<TAttribute>(
 				a => predicate(a, method), inherit));
 	}
 
+	/// <summary>
+	///     Determines whether the current <see cref="Type" /> implements the <paramref name="interfaceType" />.
+	/// </summary>
+	/// <param name="type">The <see cref="Type" />.</param>
+	/// <param name="interfaceType">The interface <see cref="Type" />.</param>
+	/// <param name="forceDirect">
+	///     If set to <see langword="false" /> (default value), the <paramref name="interfaceType" />
+	///     can be anywhere in the inheritance tree, otherwise if set to <see langword="true" /> requires the
+	///     <paramref name="interfaceType" /> to be directly implemented in the <paramref name="type"/>.
+	/// </param>
+	public static bool Implements(
+		this Type type,
+		Type interfaceType,
+		bool forceDirect = false)
+	{
+		if (!interfaceType.IsInterface)
+		{
+			return false;
+		}
+
+		Type[] interfaces = type.GetInterfaces();
+		if (forceDirect && type.BaseType != null)
+		{
+			interfaces = interfaces
+				.Except(type.BaseType.GetInterfaces())
+				.ToArray();
+		}
+
+		return interfaces
+			.Any(childInterface =>
+			{
+				Type currentInterface = childInterface.IsGenericType
+					? childInterface.GetGenericTypeDefinition()
+					: childInterface;
+
+				return currentInterface == interfaceType;
+			});
+	}
+
 	/// <summary>
 	///     Determines whether the current <see cref="Type" /> inherits from the <paramref name="parentType" />.
 	/// </summary>
@@ -78,8 +117,7 @@ public static bool HasMethodWithAttribute<TAttribute>(
 	///     can be anywhere in the inheritance tree, otherwise if set to <see langword="true" /> requires the
 	///     <paramref name="parentType" /> to be the direct parent.
 	/// </param>
-	/// <returns></returns>
-	public static bool Inherits(
+	public static bool InheritsFrom(
 		this Type type,
 		Type parentType,
 		bool forceDirect = false)
@@ -111,7 +149,7 @@ public static bool Inherits(
 				return false;
 			}
 
-			if (currentType.ImplementsInterface(parentType, forceDirect))
+			if (currentType.Implements(parentType, forceDirect))
 			{
 				return true;
 			}
@@ -137,25 +175,5 @@ public static bool Inherits(
 	public static bool IsStatic(this Type type)
 		=> type.IsAbstract && type.IsSealed && !type.IsInterface &&
 		   !type.GetConstructors().Any(m => m.IsPublic);
-
-	internal static bool ImplementsInterface(this Type type, Type interfaceType, bool forceDirect)
-	{
-		Type[] interfaces = type.GetInterfaces();
-		if (forceDirect && type.BaseType != null)
-		{
-			interfaces = interfaces
-				.Except(type.BaseType.GetInterfaces())
-				.ToArray();
-		}
-
-		return interfaces
-			.Any(childInterface =>
-			{
-				Type currentInterface = childInterface.IsGenericType
-					? childInterface.GetGenericTypeDefinition()
-					: childInterface;
-
-				return currentInterface == interfaceType;
-			});
-	}
+
 }

Source/Testably.Architecture.Rules/Filters/FilterOnTypeExtensions.Implement.cs

@@ -0,0 +1,44 @@
+using System;
+
+namespace Testably.Architecture.Rules;
+
+public static partial class FilterOnTypeExtensions
+{
+	/// <summary>
+	///     Filter for types that implement the interface <typeparamref name="TInterface" />.
+	/// </summary>
+	public static ITypeFilterResult WhichImplement<TInterface>(this ITypeFilter @this,
+		bool forceDirect = false)
+	{
+		return @this.WhichImplement(typeof(TInterface), forceDirect);
+	}
+
+	/// <summary>
+	///     Filter for types that implement the interface <paramref name="interfaceType" />.
+	/// </summary>
+	public static ITypeFilterResult WhichImplement(this ITypeFilter @this,
+		Type interfaceType,
+		bool forceDirect = false)
+	{
+		return @this.Which(type => type.Implements(interfaceType, forceDirect));
+	}
+
+	/// <summary>
+	///     Filter for types that don't implement the interface <typeparamref name="TInterface" />.
+	/// </summary>
+	public static ITypeFilterResult WhichDoNotImplement<TInterface>(this ITypeFilter @this,
+		bool forceDirect = false)
+	{
+		return @this.WhichDoNotImplement(typeof(TInterface), forceDirect);
+	}
+
+	/// <summary>
+	///     Filter for types that don't implement the interface <paramref name="interfaceType" />.
+	/// </summary>
+	public static ITypeFilterResult WhichDoNotImplement(this ITypeFilter @this,
+		Type interfaceType,
+		bool forceDirect = false)
+	{
+		return @this.Which(type => !type.Implements(interfaceType, forceDirect));
+	}
+}

Source/Testably.Architecture.Rules/Filters/FilterOnTypeExtensions.InheritFrom.cs

@@ -19,7 +19,7 @@ public static ITypeFilterResult WhichInheritFrom<TBase>(this ITypeFilter @this,
 	public static ITypeFilterResult WhichInheritFrom(this ITypeFilter @this, Type baseType,
 		bool forceDirect = false)
 	{
-		return @this.Which(type => type.Inherits(baseType, forceDirect));
+		return @this.Which(type => type.InheritsFrom(baseType, forceDirect));
 	}
 
 	/// <summary>
@@ -37,6 +37,6 @@ public static ITypeFilterResult WhichDoNotInheritFrom<TBase>(this ITypeFilter @t
 	public static ITypeFilterResult WhichDoNotInheritFrom(this ITypeFilter @this, Type baseType,
 		bool forceDirect = false)
 	{
-		return @this.Which(type => !type.Inherits(baseType, forceDirect));
+		return @this.Which(type => !type.InheritsFrom(baseType, forceDirect));
 	}
 }

Source/Testably.Architecture.Rules/Requirements/RequirementOnTypeExtensions.Implement.cs

@@ -0,0 +1,74 @@
+using System;
+
+namespace Testably.Architecture.Rules;
+
+public static partial class RequirementOnTypeExtensions
+{
+	/// <summary>
+	///     Expect the types to implement the <typeparamref name="TInterface" />.
+	/// </summary>
+	/// <typeparamref name="TInterface">The type of the interface which should be implemented.</typeparamref>
+	/// <param name="this">The <see cref="IRequirement{Type}" />.</param>
+	/// <param name="forceDirect">
+	///     If set to <see langword="false" /> (default value), the <typeparamref name="TInterface" />
+	///     can be anywhere in the inheritance tree, otherwise if set to <see langword="true" /> requires the
+	///     <typeparamref name="TInterface" /> to be directly implemented.
+	/// </param>
+	public static IRequirementResult<Type> ShouldImplement<TInterface>(
+		this IRequirement<Type> @this,
+		bool forceDirect = false)
+		=> @this.ShouldImplement(typeof(TInterface), forceDirect);
+
+	/// <summary>
+	///     Expect the types to implement the <paramref name="interfaceType" />.
+	/// </summary>
+	/// <param name="this">The <see cref="IRequirement{Type}" />.</param>
+	/// <param name="interfaceType">The interface which should be implemented.</param>
+	/// <param name="forceDirect">
+	///     If set to <see langword="false" /> (default value), the <paramref name="interfaceType" />
+	///     can be anywhere in the inheritance tree, otherwise if set to <see langword="true" /> requires the
+	///     <paramref name="interfaceType" /> to be directly implemented.
+	/// </param>
+	public static IRequirementResult<Type> ShouldImplement(
+		this IRequirement<Type> @this,
+		Type interfaceType,
+		bool forceDirect = false)
+		=> @this.ShouldSatisfy(Requirement.ForType(
+			type => type.Implements(interfaceType, forceDirect),
+			type => new TypeTestError(type,
+				$"Type '{type.Name}' should{(forceDirect ? " directly" : "")} implement '{interfaceType.Name}'.")));
+
+	/// <summary>
+	///     Expect the types to not implement the <typeparamref name="TInterface" />.
+	/// </summary>
+	/// <typeparamref name="TInterface">The type of the interface which should be implemented.</typeparamref>
+	/// <param name="this">The <see cref="IRequirement{Type}" />.</param>
+	/// <param name="forceDirect">
+	///     If set to <see langword="false" /> (default value), the <typeparamref name="TInterface" />
+	///     can be anywhere in the inheritance tree, otherwise if set to <see langword="true" /> requires the
+	///     <typeparamref name="TInterface" /> to be directly implemented.
+	/// </param>
+	public static IRequirementResult<Type> ShouldNotImplement<TInterface>(
+		this IRequirement<Type> @this,
+		bool forceDirect = false)
+		=> @this.ShouldNotImplement(typeof(TInterface), forceDirect);
+
+	/// <summary>
+	///     Expect the types to not implement the <paramref name="interfaceType" />.
+	/// </summary>
+	/// <param name="this">The <see cref="IRequirement{Type}" />.</param>
+	/// <param name="interfaceType">The interface which should be implemented.</param>
+	/// <param name="forceDirect">
+	///     If set to <see langword="false" /> (default value), the <paramref name="interfaceType" />
+	///     can be anywhere in the inheritance tree, otherwise if set to <see langword="true" /> requires the
+	///     <paramref name="interfaceType" /> to be directly implemented.
+	/// </param>
+	public static IRequirementResult<Type> ShouldNotImplement(
+		this IRequirement<Type> @this,
+		Type interfaceType,
+		bool forceDirect = false)
+		=> @this.ShouldSatisfy(Requirement.ForType(
+			type => !type.Implements(interfaceType, forceDirect),
+			type => new TypeTestError(type,
+				$"Type '{type.Name}' should not{(forceDirect ? " directly" : "")} implement '{interfaceType.Name}'.")));
+}

Source/Testably.Architecture.Rules/Requirements/RequirementOnTypeExtensions.InheritFrom.cs

@@ -33,7 +33,7 @@ public static IRequirementResult<Type> ShouldInheritFrom(
 		Type baseType,
 		bool forceDirect = false)
 		=> @this.ShouldSatisfy(Requirement.ForType(
-			type => type.Inherits(baseType, forceDirect),
+			type => type.InheritsFrom(baseType, forceDirect),
 			type => new TypeTestError(type,
 				$"Type '{type.Name}' should{(forceDirect ? " directly" : "")} inherit from '{baseType.Name}'.")));
 
@@ -66,7 +66,7 @@ public static IRequirementResult<Type> ShouldNotInheritFrom(
 		Type baseType,
 		bool forceDirect = false)
 		=> @this.ShouldSatisfy(Requirement.ForType(
-			type => !type.Inherits(baseType, forceDirect),
+			type => !type.InheritsFrom(baseType, forceDirect),
 			type => new TypeTestError(type,
 				$"Type '{type.Name}' should not{(forceDirect ? " directly" : "")} inherit from '{baseType.Name}'.")));
 }

Tests/Testably.Architecture.Rules.Tests/Extensions/TypeExtensionsTests.cs

@@ -85,11 +85,11 @@ public void HasMethodWithAttribute_WithPredicate_ShouldReturnPredicateResult()
 	[Theory]
 	[InlineData(false)]
 	[InlineData(true)]
-	public void ImplementsInterface_Object_ShouldReturnFalse(bool forceDirect)
+	public void Implements_Object_ShouldReturnFalse(bool forceDirect)
 	{
 		Type sut = typeof(object);
 
-		bool result = sut.ImplementsInterface(typeof(IFooInterface), forceDirect);
+		bool result = sut.Implements(typeof(IFooInterface), forceDirect);
 
 		result.Should().BeFalse();
 	}

Tests/Testably.Architecture.Rules.Tests/Filters/FilterOnTypeExtensionsTests.Implement.cs

@@ -0,0 +1,123 @@
+using FluentAssertions;
+using Testably.Architecture.Rules.Tests.TestHelpers;
+using Xunit;
+
+namespace Testably.Architecture.Rules.Tests.Filters;
+
+public sealed partial class FilterOnTypeExtensionsTests
+{
+	public sealed class ImplementTests
+	{
+		[Theory]
+		[InlineData(false)]
+		[InlineData(true)]
+		public void WhichImplement_WithClass_ShouldReturnFalse(bool forceDirect)
+		{
+			ITestResult result = Expect.That.Types
+				.WhichImplement<FooImplementor1>(forceDirect)
+				.ShouldAlwaysFail()
+				.AllowEmpty()
+				.Check.InAllLoadedAssemblies();
+
+			result.ShouldNotBeViolated();
+		}
+
+		[Fact]
+		public void
+			WhichImplement_WithInterface_WithForceDirect_ShouldReturnTypesDirectlyImplementingTheInterface()
+		{
+			ITestResult result = Expect.That.Types
+				.WhichImplement<IFooInterface>(true)
+				.ShouldAlwaysFail()
+				.Check.InAllLoadedAssemblies();
+
+			result.Errors.Length.Should().Be(2);
+			result.Errors.Should()
+				.Contain(e => e.ToString().Contains(nameof(FooImplementor1)));
+			result.Errors.Should()
+				.NotContain(e => e.ToString().Contains(nameof(FooImplementor2)));
+			result.Errors.Should()
+				.Contain(e => e.ToString().Contains(typeof(FooGenericImplementor1<>).Name));
+			result.Errors.Should()
+				.NotContain(e => e.ToString().Contains(typeof(FooGenericImplementor2<>).Name));
+		}
+
+		[Fact]
+		public void
+			WhichImplement_WithInterface_WithoutForceDirect_ShouldReturnAllTypesImplementingInterface()
+		{
+			ITestResult result = Expect.That.Types
+				.WhichImplement<IFooInterface>()
+				.ShouldAlwaysFail()
+				.Check.InAllLoadedAssemblies();
+
+			result.Errors.Length.Should().Be(4);
+			result.Errors.Should()
+				.Contain(e => e.ToString().Contains(nameof(FooImplementor1)));
+			result.Errors.Should()
+				.Contain(e => e.ToString().Contains(nameof(FooImplementor2)));
+			result.Errors.Should()
+				.Contain(e => e.ToString().Contains(typeof(FooGenericImplementor1<>).Name));
+			result.Errors.Should()
+				.Contain(e => e.ToString().Contains(typeof(FooGenericImplementor2<>).Name));
+		}
+
+		[Fact]
+		public void
+			WhichImplement_WithGenericInterface_WithForceDirect_ShouldReturnTypesDirectlyImplementingTheInterface()
+		{
+			ITestResult result = Expect.That.Types
+				.WhichImplement(typeof(IGenericFooInterface<>), true)
+				.ShouldAlwaysFail()
+				.Check.InAllLoadedAssemblies();
+
+			result.Errors.Length.Should().Be(1);
+			result.Errors.Should()
+				.Contain(e => e.ToString().Contains(typeof(FooGenericImplementor1<>).Name));
+			result.Errors.Should()
+				.NotContain(e => e.ToString().Contains(typeof(FooGenericImplementor2<>).Name));
+		}
+
+		[Fact]
+		public void
+			WhichImplement_WithGenericInterface_WithoutForceDirect_ShouldReturnAllTypesImplementingInterface()
+		{
+			ITestResult result = Expect.That.Types
+				.WhichImplement(typeof(IGenericFooInterface<>))
+				.ShouldAlwaysFail()
+				.Check.InAllLoadedAssemblies();
+
+			result.Errors.Length.Should().Be(2);
+			result.Errors.Should()
+				.Contain(e => e.ToString().Contains(typeof(FooGenericImplementor1<>).Name));
+			result.Errors.Should()
+				.Contain(e => e.ToString().Contains(typeof(FooGenericImplementor2<>).Name));
+		}
+
+		private class FooGenericImplementor1<T> : IGenericFooInterface<T>,
+			IFooInterface
+		{
+		}
+
+		private class FooGenericImplementor2<T> : FooGenericImplementor1<T>
+		{
+		}
+
+		private class FooImplementor1 : IFooInterface
+		{
+		}
+
+		private class FooImplementor2 : FooImplementor1
+		{
+		}
+
+		private interface IFooInterface
+		{
+		}
+
+		// ReSharper disable once UnusedTypeParameter
+		private interface IGenericFooInterface<T>
+		{
+		}
+	}
+}