Make the use of Assembly.CodeBase more robust

src/Microsoft.AspNetCore.Mvc.Core/ApplicationParts/RelatedAssemblyAttribute.cs

@@ -50,10 +50,14 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationParts
                 throw new ArgumentNullException(nameof(assembly));
             }
 
-            return GetRelatedAssemblies(assembly, throwOnError, AssemblyLoadFileDelegate);
+            return GetRelatedAssemblies(assembly, throwOnError, File.Exists, AssemblyLoadFileDelegate);
         }
 
-        internal static IReadOnlyList<Assembly> GetRelatedAssemblies(Assembly assembly, bool throwOnError, Func<string, Assembly> loadFile)
+        internal static IReadOnlyList<Assembly> GetRelatedAssemblies(
+            Assembly assembly,
+            bool throwOnError,
+            Func<string, bool> fileExists,
+            Func<string, Assembly> loadFile)
         {
             if (assembly == null)
             {
@@ -74,7 +78,8 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationParts
             }
 
             var assemblyName = assembly.GetName().Name;
-            var assemblyDirectory = Path.GetDirectoryName(assembly.CodeBase);
+            var assemblyLocation = GetAssemblyLocation(assembly);
+            var assemblyDirectory = Path.GetDirectoryName(assemblyLocation);
 
             var relatedAssemblies = new List<Assembly>();
             for (var i = 0; i < attributes.Length; i++)
@@ -87,7 +92,7 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationParts
                 }
 
                 var relatedAssemblyLocation = Path.Combine(assemblyDirectory, attribute.AssemblyFileName + ".dll");
-                if (!File.Exists(relatedAssemblyLocation))
+                if (!fileExists(relatedAssemblyLocation))
                 {
                     if (throwOnError)
                     {
@@ -107,5 +112,15 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationParts
 
             return relatedAssemblies;
         }
+
+        internal static string GetAssemblyLocation(Assembly assembly)
+        {
+            if (Uri.TryCreate(assembly.CodeBase, UriKind.Absolute, out var result) && result.IsFile)
+            {
+                return result.LocalPath;
+            }
+
+            return assembly.Location;
+        }
     }
 }

test/Microsoft.AspNetCore.Mvc.Core.Test/ApplicationParts/RelatedAssemblyPartTest.cs

@@ -67,20 +67,46 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationParts
             };
             var relatedAssembly = typeof(RelatedAssemblyPartTest).Assembly;
 
-            try
+            var result = RelatedAssemblyAttribute.GetRelatedAssemblies(assembly, throwOnError: true, file => true, file =>
             {
-                File.WriteAllBytes(destination, new byte[0]);
+                Assert.Equal(file, destination);
-                var result = RelatedAssemblyAttribute.GetRelatedAssemblies(assembly, throwOnError: true, file =>
+                return relatedAssembly;
-                {
+            });
-                    Assert.Equal(file, destination);
+            Assert.Equal(new[] { relatedAssembly }, result);
-                    return relatedAssembly;
+        }
-                });
+
-                Assert.Equal(new[] { relatedAssembly }, result);
+        [Fact]
-            }
+        public void GetAssemblyLocation_UsesCodeBase()
-            finally
+        {
+            // Arrange
+            var destination = Path.Combine(AssemblyDirectory, "RelatedAssembly.dll");
+            var codeBase = "file://x/file/Assembly.dll";
+            var expected = new Uri(codeBase).LocalPath;
+            var assembly = new TestAssembly
             {
-                File.Delete(destination);
+                CodeBaseSettable = codeBase,
-            }
+            };
+
+            // Act
+            var actual = RelatedAssemblyAttribute.GetAssemblyLocation(assembly);
+            Assert.Equal(expected, actual);
+        }
+
+        [Fact]
+        public void GetAssemblyLocation_UsesLocation_IfCodeBaseIsNotLocal()
+        {
+            // Arrange
+            var destination = Path.Combine(AssemblyDirectory, "RelatedAssembly.dll");
+            var expected = Path.Combine(AssemblyDirectory, "Some-Dir", "Assembly.dll");
+            var assembly = new TestAssembly
+            {
+                CodeBaseSettable = "https://www.microsoft.com/test.dll",
+                LocationSettable = expected,
+            };
+
+            // Act
+            var actual = RelatedAssemblyAttribute.GetAssemblyLocation(assembly);
+            Assert.Equal(expected, actual);
         }
 
         private class TestAssembly : Assembly
@@ -92,7 +118,13 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationParts
 
             public string AttributeAssembly { get; set; }
 
-            public override string CodeBase => Path.Combine(AssemblyDirectory, "MyAssembly.dll");
+            public string CodeBaseSettable { get; set; } = Path.Combine(AssemblyDirectory, "MyAssembly.dll");
+
+            public override string CodeBase => CodeBaseSettable;
+
+            public string LocationSettable { get; set; } = Path.Combine(AssemblyDirectory, "MyAssembly.dll");
+
+            public override string Location => LocationSettable;
 
             public override object[] GetCustomAttributes(Type attributeType, bool inherit)
             {