Add polyfill for Type.IsAssignableFrom(...) (#15)

Tyrrrz · Sep 30, 2024 · e56ec5f · e56ec5f
1 parent 787d847
commit e56ec5f
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Showing 4 changed files with 38 additions and 8 deletions.
diff --git a/PolyShim.Tests/Net50/TypeTests.cs b/PolyShim.Tests/Net50/TypeTests.cs
@@ -5,15 +5,23 @@ namespace PolyShim.Tests.Net50;
 
 public class TypeTests
 {
-    private class BaseClass;
+    private interface IBaseInterface;
+
+    private class BaseClass : IBaseInterface;
 
     private class DerivedClass : BaseClass;
 
     [Fact]
     public void IsAssignableTo_Test()
     {
-        typeof(DerivedClass).IsAssignableTo(typeof(BaseClass)).Should().BeTrue();
         typeof(DerivedClass).IsAssignableTo(typeof(DerivedClass)).Should().BeTrue();
+        typeof(DerivedClass).IsAssignableTo(typeof(BaseClass)).Should().BeTrue();
+        typeof(DerivedClass).IsAssignableTo(typeof(IBaseInterface)).Should().BeTrue();
+        typeof(BaseClass).IsAssignableTo(typeof(BaseClass)).Should().BeTrue();
         typeof(BaseClass).IsAssignableTo(typeof(DerivedClass)).Should().BeFalse();
+        typeof(BaseClass).IsAssignableTo(typeof(IBaseInterface)).Should().BeTrue();
+        typeof(IBaseInterface).IsAssignableTo(typeof(IBaseInterface)).Should().BeTrue();
+        typeof(IBaseInterface).IsAssignableTo(typeof(DerivedClass)).Should().BeFalse();
+        typeof(IBaseInterface).IsAssignableTo(typeof(BaseClass)).Should().BeFalse();
     }
 }
diff --git a/PolyShim.Tests/NetCore20/TypeTests.cs b/PolyShim.Tests/NetCore20/TypeTests.cs
@@ -5,15 +5,37 @@ namespace PolyShim.Tests.NetCore20;
 
 public class TypeTests
 {
-    private class BaseClass;
+    private interface IBaseInterface;
+
+    private class BaseClass : IBaseInterface;
 
     private class DerivedClass : BaseClass;
 
+    [Fact]
+    public void IsAssignableFrom_Test()
+    {
+        typeof(DerivedClass).IsAssignableFrom(typeof(DerivedClass)).Should().BeTrue();
+        typeof(DerivedClass).IsAssignableFrom(typeof(BaseClass)).Should().BeFalse();
+        typeof(DerivedClass).IsAssignableFrom(typeof(IBaseInterface)).Should().BeFalse();
+        typeof(BaseClass).IsAssignableFrom(typeof(BaseClass)).Should().BeTrue();
+        typeof(BaseClass).IsAssignableFrom(typeof(DerivedClass)).Should().BeTrue();
+        typeof(BaseClass).IsAssignableFrom(typeof(IBaseInterface)).Should().BeFalse();
+        typeof(IBaseInterface).IsAssignableFrom(typeof(IBaseInterface)).Should().BeTrue();
+        typeof(IBaseInterface).IsAssignableFrom(typeof(DerivedClass)).Should().BeTrue();
+        typeof(IBaseInterface).IsAssignableFrom(typeof(BaseClass)).Should().BeTrue();
+    }
+
     [Fact]
     public void IsSubclassOf_Test()
     {
-        typeof(DerivedClass).IsSubclassOf(typeof(BaseClass)).Should().BeTrue();
         typeof(DerivedClass).IsSubclassOf(typeof(DerivedClass)).Should().BeFalse();
+        typeof(DerivedClass).IsSubclassOf(typeof(BaseClass)).Should().BeTrue();
+        typeof(DerivedClass).IsSubclassOf(typeof(IBaseInterface)).Should().BeFalse();
+        typeof(BaseClass).IsSubclassOf(typeof(BaseClass)).Should().BeFalse();
         typeof(BaseClass).IsSubclassOf(typeof(DerivedClass)).Should().BeFalse();
+        typeof(BaseClass).IsSubclassOf(typeof(IBaseInterface)).Should().BeFalse();
+        typeof(IBaseInterface).IsSubclassOf(typeof(IBaseInterface)).Should().BeFalse();
+        typeof(IBaseInterface).IsSubclassOf(typeof(DerivedClass)).Should().BeFalse();
+        typeof(IBaseInterface).IsSubclassOf(typeof(BaseClass)).Should().BeFalse();
     }
 }
diff --git a/PolyShim/Net50/Type.cs b/PolyShim/Net50/Type.cs
@@ -12,10 +12,6 @@ internal static partial class PolyfillExtensions
 {
     // https://learn.microsoft.com/en-us/dotnet/api/system.type.isassignableto
     public static bool IsAssignableTo(this Type type, Type? otherType) =>
-#if NETSTANDARD && !NETSTANDARD2_0_OR_GREATER
-        otherType?.GetTypeInfo().IsAssignableFrom(type.GetTypeInfo()) == true;
-#else
         otherType?.IsAssignableFrom(type) == true;
-#endif
 }
 #endif
diff --git a/PolyShim/NetCore20/Type.cs b/PolyShim/NetCore20/Type.cs
@@ -10,6 +10,10 @@
 
 internal static partial class PolyfillExtensions
 {
+    // https://learn.microsoft.com/en-us/dotnet/api/system.type.isassignablefrom
+    public static bool IsAssignableFrom(this Type type, Type otherType) =>
+        type.GetTypeInfo().IsAssignableFrom(otherType.GetTypeInfo());
+
     // https://learn.microsoft.com/en-us/dotnet/api/system.type.issubclassof
     public static bool IsSubclassOf(this Type type, Type otherType)
     {