TypeLoader: implement Try methods (#1358)

* TypeLoader: implement Try methods

* fix

src/WireMock.Net.MimePart/Util/MimeKitUtils.cs

@@ -1,7 +1,6 @@
 // Copyright © WireMock.Net
 
 using System;
-using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Linq;
@@ -33,16 +32,25 @@ internal class MimeKitUtils : IMimeKitUtils
             StartsWithMultiPart(contentTypeHeader)
         )
         {
-            var bytes = requestMessage.BodyData?.DetectedBodyType switch
+            byte[] bytes;
+
+            switch (requestMessage.BodyData?.DetectedBodyType)
             {
                 // If the body is bytes, use the BodyAsBytes to match on.
-                BodyType.Bytes => requestMessage.BodyData.BodyAsBytes!,
+                case BodyType.Bytes:
+                    bytes = requestMessage.BodyData.BodyAsBytes!;
+                    break;
 
                 // If the body is a String or MultiPart, use the BodyAsString to match on.
-                BodyType.String or BodyType.MultiPart => Encoding.UTF8.GetBytes(requestMessage.BodyData.BodyAsString!),
+                case BodyType.String or BodyType.MultiPart:
+                    bytes = Encoding.UTF8.GetBytes(requestMessage.BodyData.BodyAsString!);
+                    break;
 
-                _ => throw new NotSupportedException()
+                // Else return false.
-            };
+                default:
+                    mimeMessageData = null;
+                    return false;
+            }
 
             var fixedBytes = FixBytes(bytes, contentTypeHeader[0]);
 

src/WireMock.Net.Minimal/Matchers/Request/RequestMessageMultiPartMatcher.cs

@@ -12,7 +12,7 @@ namespace WireMock.Matchers.Request;
 /// </summary>
 public class RequestMessageMultiPartMatcher : IRequestMatcher
 {
-    private static readonly IMimeKitUtils MimeKitUtils = TypeLoader.LoadStaticInstance<IMimeKitUtils>();
+    private readonly IMimeKitUtils _mimeKitUtils = LoadMimeKitUtils();
 
     /// <summary>
     /// The matchers.
@@ -62,7 +62,7 @@ public class RequestMessageMultiPartMatcher : IRequestMatcher
             return requestMatchResult.AddScore(GetType(), score, null);
         }
 
-        if (!MimeKitUtils.TryGetMimeMessage(requestMessage, out var message))
+        if (!_mimeKitUtils.TryGetMimeMessage(requestMessage, out var message))
         {
             return requestMatchResult.AddScore(GetType(), score, null);
         }
@@ -96,4 +96,14 @@ public class RequestMessageMultiPartMatcher : IRequestMatcher
 
         return requestMatchResult.AddScore(GetType(), score, exception);
     }
+
+    private static IMimeKitUtils LoadMimeKitUtils()
+    {
+        if (TypeLoader.TryLoadStaticInstance<IMimeKitUtils>(out var mimeKitUtils))
+        {
+            return mimeKitUtils;
+        }
+
+        throw new InvalidOperationException("MimeKit is required for RequestMessageMultiPartMatcher. Please install the WireMock.Net.MimePart package.");
+    }
 }

src/WireMock.Net.Minimal/Owin/Mappers/OwinResponseMapper.cs

@@ -178,9 +178,12 @@ namespace WireMock.Owin.Mappers
                     return (bodyData.Encoding ?? _utf8NoBom).GetBytes(jsonBody);
 
                 case BodyType.ProtoBuf:
-                    var protoDefinitions = bodyData.ProtoDefinition?.Invoke().Texts;
+                    if (TypeLoader.TryLoadStaticInstance<IProtoBufUtils>(out var protoBufUtils))
-                    var protoBufUtils = TypeLoader.LoadStaticInstance<IProtoBufUtils>();
+                    {
-                    return await protoBufUtils.GetProtoBufMessageWithHeaderAsync(protoDefinitions, bodyData.ProtoBufMessageType, bodyData.BodyAsJson).ConfigureAwait(false);
+                        var protoDefinitions = bodyData.ProtoDefinition?.Invoke().Texts;
+                        return await protoBufUtils.GetProtoBufMessageWithHeaderAsync(protoDefinitions, bodyData.ProtoBufMessageType, bodyData.BodyAsJson).ConfigureAwait(false);
+                    }
+                    break;
 
                 case BodyType.Bytes:
                     return bodyData.BodyAsBytes;

src/WireMock.Net.Minimal/RequestMessage.cs

@@ -183,16 +183,9 @@ public class RequestMessage : IRequestMessage
 #endif
 
 #if MIMEKIT
-        try
+        if (TypeLoader.TryLoadStaticInstance<IMimeKitUtils>(out var mimeKitUtils) && mimeKitUtils.TryGetMimeMessage(this, out var mimeMessage))
         {
-            if (TypeLoader.LoadStaticInstance<IMimeKitUtils>().TryGetMimeMessage(this, out var mimeMessage))
+            BodyAsMimeMessage = mimeMessage;
-            {
-                BodyAsMimeMessage = mimeMessage;
-            }
-        }
-        catch
-        {
-            // Ignore exception from MimeMessage.Load
         }
 #endif
     }

src/WireMock.Net.Minimal/Serialization/MatcherMapper.cs

@@ -55,7 +55,12 @@ internal class MatcherMapper
             case "CSharpCodeMatcher":
                 if (_settings.AllowCSharpCodeMatcher == true)
                 {
-                    return TypeLoader.LoadNewInstance<ICSharpCodeMatcher>(matchBehaviour, matchOperator, stringPatterns);
+                    if (TypeLoader.TryLoadNewInstance<ICSharpCodeMatcher>(out var csharpCodeMatcher, matchBehaviour, matchOperator, stringPatterns))
+                    {
+                        return csharpCodeMatcher;
+                    }
+
+                    throw new InvalidOperationException("The 'CSharpCodeMatcher' cannot be loaded. Please install the WireMock.Net.Matchers.CSharpCode package.");
                 }
 
                 throw new NotSupportedException("It's not allowed to use the 'CSharpCodeMatcher' because WireMockServerSettings.AllowCSharpCodeMatcher is not set to 'true'.");
@@ -75,7 +80,12 @@ internal class MatcherMapper
             case "GraphQLMatcher":
                 var patternAsString = stringPatterns[0].GetPattern();
                 var schema = new AnyOf<string, StringPattern, ISchemaData>(patternAsString);
-                return TypeLoader.LoadNewInstance<IGraphQLMatcher>(schema, matcherModel.CustomScalars, matchBehaviour, matchOperator);
+                if (TypeLoader.TryLoadNewInstance<IGraphQLMatcher>(out var graphQLMatcher, schema, matcherModel.CustomScalars, matchBehaviour, matchOperator))
+                {
+                    return graphQLMatcher;
+                }
+
+                throw new InvalidOperationException("The 'GraphQLMatcher' cannot be loaded. Please install the WireMock.Net.GraphQL package.");
 
             case "MimePartMatcher":
                 return CreateMimePartMatcher(matchBehaviour, matcherModel);
@@ -282,18 +292,34 @@ internal class MatcherMapper
         var contentTransferEncodingMatcher = Map(matcher.ContentTransferEncodingMatcher) as IStringMatcher;
         var contentMatcher = Map(matcher.ContentMatcher);
 
-        return TypeLoader.LoadNewInstance<IMimePartMatcher>(matchBehaviour, contentTypeMatcher, contentDispositionMatcher, contentTransferEncodingMatcher, contentMatcher);
+        if (TypeLoader.TryLoadNewInstance<IMimePartMatcher>(
+            out var mimePartMatcher,
+            matchBehaviour,
+            contentTypeMatcher,
+            contentDispositionMatcher,
+            contentTransferEncodingMatcher,
+            contentMatcher))
+        {
+            return mimePartMatcher;
+        }
+
+        throw new InvalidOperationException("The 'MimePartMatcher' cannot be loaded. Please install the WireMock.Net.MimePart package.");
     }
 
     private IProtoBufMatcher CreateProtoBufMatcher(MatchBehaviour? matchBehaviour, IReadOnlyList<string> protoDefinitions, MatcherModel matcher)
     {
         var objectMatcher = Map(matcher.ContentMatcher) as IObjectMatcher;
 
-        return TypeLoader.LoadNewInstance<IProtoBufMatcher>(
+        if (TypeLoader.TryLoadNewInstance<IProtoBufMatcher>(
+            out var protobufMatcher,
             () => ProtoDefinitionUtils.GetIdOrTexts(_settings, protoDefinitions.ToArray()),
             matcher.ProtoBufMessageType!,
             matchBehaviour ?? MatchBehaviour.AcceptOnMatch,
-            objectMatcher
+            objectMatcher))
-        );
+        {
+            return protobufMatcher;
+        }
+
+        throw new InvalidOperationException("The 'ProtoBufMatcher' cannot be loaded. Please install the WireMock.Net.ProtoBuf package.");
     }
 }

src/WireMock.Net.Minimal/Server/WireMockServer.ConvertMapping.cs

@@ -366,10 +366,8 @@ public partial class WireMockServer
         }
         else if (responseModel.BodyAsJson != null)
         {
-            if (responseModel.ProtoBufMessageType != null)
+            if (responseModel.ProtoBufMessageType != null && TypeLoader.TryLoadStaticInstance<IProtoBufUtils>(out var protoBufUtils))
             {
-                var protoBufUtils = TypeLoader.LoadStaticInstance<IProtoBufUtils>();
-
                 if (responseModel.ProtoDefinition != null)
                 {
                     responseBuilder = protoBufUtils.UpdateResponseBuilder(responseBuilder, responseModel.ProtoBufMessageType, responseModel.BodyAsJson, responseModel.ProtoDefinition);

src/WireMock.Net.Shared/Matchers/Request/RequestMessageGraphQLMatcher.cs

@@ -100,7 +100,10 @@ public class RequestMessageGraphQLMatcher : IRequestMatcher
         IDictionary<string, Type>? customScalars
     )
     {
-        var graphQLMatcher = TypeLoader.LoadNewInstance<IGraphQLMatcher>(schema, customScalars, matchBehaviour, MatchOperator.Or);
+        if (TypeLoader.TryLoadNewInstance<IGraphQLMatcher>(out var graphQLMatcher, schema, customScalars, matchBehaviour, MatchOperator.Or))
-        return [graphQLMatcher];
+        {
+            return [graphQLMatcher];
+        }
+        return [];
     }
 }

src/WireMock.Net.Shared/Matchers/Request/RequestMessageProtoBufMatcher.cs

@@ -25,7 +25,10 @@ public class RequestMessageProtoBufMatcher : IRequestMatcher
     /// <param name="matcher">The optional matcher to use to match the ProtoBuf as (json) object.</param>
     public RequestMessageProtoBufMatcher(MatchBehaviour matchBehaviour, Func<IdOrTexts> protoDefinition, string messageType, IObjectMatcher? matcher = null)
     {
-        Matcher = TypeLoader.LoadNewInstance<IProtoBufMatcher>(protoDefinition, messageType, matchBehaviour, matcher);
+        if (TypeLoader.TryLoadNewInstance<IProtoBufMatcher>(out var protoBufMatcher, protoDefinition, messageType, matchBehaviour, matcher))
+        {
+            Matcher = protoBufMatcher;
+        }
     }
 
     /// <inheritdoc />

src/WireMock.Net.Shared/Util/TypeLoader.cs

@@ -14,68 +14,130 @@ internal static class TypeLoader
 {
     private static readonly ConcurrentDictionary<string, Type> Assemblies = new();
     private static readonly ConcurrentDictionary<Type, object> Instances = new();
+    private static readonly ConcurrentBag<(string FullName, Type Type)> InstancesWhichCannotBeFoundByFullName = [];
+    private static readonly ConcurrentBag<(string FullName, Type Type)> StaticInstancesWhichCannotBeFoundByFullName = [];
+    private static readonly ConcurrentBag<Type> InstancesWhichCannotBeFound = [];
+    private static readonly ConcurrentBag<Type> StaticInstancesWhichCannotBeFound = [];
 
-    public static TInterface LoadNewInstance<TInterface>(params object?[] args) where TInterface : class
+    public static bool TryLoadNewInstance<TInterface>([NotNullWhen(true)] out TInterface? instance, params object?[] args) where TInterface : class
     {
-        var pluginType = GetPluginType<TInterface>();
+        var type = typeof(TInterface);
+        if (InstancesWhichCannotBeFound.Contains(type))
+        {
+            instance = null;
+            return false;
+        }
 
-        return (TInterface)Activator.CreateInstance(pluginType, args)!;
+        if (TryGetPluginType<TInterface>(out var pluginType))
+        {
+            instance = (TInterface)Activator.CreateInstance(pluginType, args)!;
+            return true;
+        }
+
+        InstancesWhichCannotBeFound.Add(type);
+        instance = null;
+        return false;
     }
 
-    public static TInterface LoadStaticInstance<TInterface>(params object?[] args) where TInterface : class
+    public static bool TryLoadStaticInstance<TInterface>([NotNullWhen(true)] out TInterface? staticInstance, params object?[] args) where TInterface : class
     {
-        var pluginType = GetPluginType<TInterface>();
+        var type = typeof(TInterface);
+        if (StaticInstancesWhichCannotBeFound.Contains(type))
+        {
+            staticInstance = null;
+            return false;
+        }
 
-        return (TInterface)Instances.GetOrAdd(pluginType, key => Activator.CreateInstance(key, args)!);
+        if (TryGetPluginType<TInterface>(out var pluginType))
+        {
+            staticInstance = (TInterface)Instances.GetOrAdd(pluginType, key => Activator.CreateInstance(key, args)!);
+            return true;
+        }
+
+        StaticInstancesWhichCannotBeFound.Add(type);
+        staticInstance = null;
+        return false;
     }
 
-    public static TInterface LoadNewInstanceByFullName<TInterface>(string implementationTypeFullName, params object?[] args) where TInterface : class
+    public static bool TryLoadNewInstanceByFullName<TInterface>([NotNullWhen(true)] out TInterface? instance, string implementationTypeFullName, params object?[] args) where TInterface : class
     {
         Guard.NotNullOrEmpty(implementationTypeFullName);
 
-        var pluginType = GetPluginTypeByFullName<TInterface>(implementationTypeFullName);
+        var type = typeof(TInterface);
+        if (InstancesWhichCannotBeFoundByFullName.Contains((implementationTypeFullName, type)))
+        {
+            instance = null;
+            return false;
+        }
 
-        return (TInterface)Activator.CreateInstance(pluginType, args)!;
+        if (TryGetPluginTypeByFullName<TInterface>(implementationTypeFullName, out var pluginType))
+        {
+            instance = (TInterface)Activator.CreateInstance(pluginType, args)!;
+            return true;
+        }
+
+        InstancesWhichCannotBeFoundByFullName.Add((implementationTypeFullName, type));
+        instance = null;
+        return false;
     }
 
-    public static TInterface LoadStaticInstanceByFullName<TInterface>(string implementationTypeFullName, params object?[] args) where TInterface : class
+    public static bool TryLoadStaticInstanceByFullName<TInterface>([NotNullWhen(true)] out TInterface? staticInstance, string implementationTypeFullName, params object?[] args) where TInterface : class
     {
         Guard.NotNullOrEmpty(implementationTypeFullName);
 
-        var pluginType = GetPluginTypeByFullName<TInterface>(implementationTypeFullName);
+        var type = typeof(TInterface);
+        if (StaticInstancesWhichCannotBeFoundByFullName.Contains((implementationTypeFullName, type)))
+        {
+            staticInstance = null;
+            return false;
+        }
 
-        return (TInterface)Instances.GetOrAdd(pluginType, key => Activator.CreateInstance(key, args)!);
+        if (TryGetPluginTypeByFullName<TInterface>(implementationTypeFullName, out var pluginType))
+        {
+            staticInstance = (TInterface)Instances.GetOrAdd(pluginType, key => Activator.CreateInstance(key, args)!);
+            return true;
+        }
+
+        StaticInstancesWhichCannotBeFoundByFullName.Add((implementationTypeFullName, type));
+        staticInstance = null;
+        return false;
     }
 
-    private static Type GetPluginType<TInterface>() where TInterface : class
+    private static bool TryGetPluginType<TInterface>([NotNullWhen(true)] out Type? foundType) where TInterface : class
     {
         var key = typeof(TInterface).FullName!;
 
-        return Assemblies.GetOrAdd(key, _ =>
+        if (Assemblies.TryGetValue(key, out foundType))
         {
-            if (TryFindTypeInDlls<TInterface>(null, out var foundType))
+            return true;
-            {
+        }
-                return foundType;
-            }
 
-            throw new DllNotFoundException($"No dll found which implements interface '{key}'.");
+        if (TryFindTypeInDlls<TInterface>(null, out foundType))
-        });
+        {
+            Assemblies.TryAdd(key, foundType);
+            return true;
+        }
+
+        return false;
     }
 
-    private static Type GetPluginTypeByFullName<TInterface>(string implementationTypeFullName) where TInterface : class
+    private static bool TryGetPluginTypeByFullName<TInterface>(string implementationTypeFullName, [NotNullWhen(true)] out Type? foundType) where TInterface : class
     {
         var @interface = typeof(TInterface).FullName;
         var key = $"{@interface}_{implementationTypeFullName}";
 
-        return Assemblies.GetOrAdd(key, _ =>
+        if (Assemblies.TryGetValue(key, out foundType))
         {
-            if (TryFindTypeInDlls<TInterface>(implementationTypeFullName, out var foundType))
+            return true;
-            {
+        }
-                return foundType;
-            }
 
-            throw new DllNotFoundException($"No dll found which implements Interface '{@interface}' and has FullName '{implementationTypeFullName}'.");
+        if (TryFindTypeInDlls<TInterface>(implementationTypeFullName, out foundType))
-        });
+        {
+            Assemblies.TryAdd(key, foundType);
+            return true;
+        }
+
+        return false;
     }
 
     private static bool TryFindTypeInDlls<TInterface>(string? implementationTypeFullName, [NotNullWhen(true)] out Type? pluginType) where TInterface : class

test/WireMock.Net.Tests/Util/TypeLoaderTests.cs

@@ -1,6 +1,5 @@
 // Copyright © WireMock.Net
 
-using System;
 using System.IO;
 using AnyOfTypes;
 using FluentAssertions;
@@ -56,7 +55,7 @@ public class TypeLoaderTests
     }
 
     [Fact]
-    public void LoadNewInstance()
+    public void TryLoadNewInstance()
     {
         var current = Directory.GetCurrentDirectory();
         try
@@ -65,10 +64,11 @@ public class TypeLoaderTests
 
             // Act
             AnyOf<string, StringPattern> pattern = "x";
-            var result = TypeLoader.LoadNewInstance<ICSharpCodeMatcher>(MatchBehaviour.AcceptOnMatch, MatchOperator.Or, pattern);
+            var result = TypeLoader.TryLoadNewInstance<ICSharpCodeMatcher>(out var instance, MatchBehaviour.AcceptOnMatch, MatchOperator.Or, pattern);
 
             // Assert
-            result.Should().NotBeNull();
+            result.Should().BeTrue();
+            instance.Should().BeOfType<CSharpCodeMatcher>();
         }
         finally
         {
@@ -77,63 +77,66 @@ public class TypeLoaderTests
     }
 
     [Fact]
-    public void LoadNewInstanceByFullName()
+    public void TryLoadNewInstanceByFullName()
     {
         // Act
-        var result = TypeLoader.LoadNewInstanceByFullName<IDummyInterfaceWithImplementation>(typeof(DummyClass).FullName!);
+        var result = TypeLoader.TryLoadNewInstanceByFullName<IDummyInterfaceWithImplementation>(out var instance, typeof(DummyClass).FullName!);
 
         // Assert
-        result.Should().BeOfType<DummyClass>();
+        result.Should().BeTrue();
+        instance.Should().BeOfType<DummyClass>();
     }
 
     [Fact]
-    public void LoadStaticInstance_ShouldOnlyCreateInstanceOnce()
+    public void TryLoadStaticInstance_ShouldOnlyCreateInstanceOnce()
     {
         // Arrange
         var counter = new Counter();
 
         // Act
-        var result = TypeLoader.LoadStaticInstance<IDummyInterfaceWithImplementationUsedForStaticTest>(counter);
+        var result = TypeLoader.TryLoadStaticInstance<IDummyInterfaceWithImplementationUsedForStaticTest>(out var staticInstance, counter);
-        TypeLoader.LoadStaticInstance<IDummyInterfaceWithImplementationUsedForStaticTest>(counter);
+        TypeLoader.TryLoadStaticInstance(out staticInstance, counter);
 
         // Assert
-        result.Should().BeOfType<DummyClass1UsedForStaticTest>();
+        result.Should().BeTrue();
+        staticInstance.Should().BeOfType<DummyClass1UsedForStaticTest>();
         counter.Value.Should().Be(1);
     }
 
     [Fact]
-    public void LoadStaticInstanceByFullName_ShouldOnlyCreateInstanceOnce()
+    public void TryLoadStaticInstanceByFullName_ShouldOnlyCreateInstanceOnce()
     {
         // Arrange
         var counter = new Counter();
         var fullName = typeof(DummyClass2UsedForStaticTest).FullName!;
 
         // Act
-        var result = TypeLoader.LoadStaticInstanceByFullName<IDummyInterfaceWithImplementationUsedForStaticTest>(fullName, counter);
+        var result = TypeLoader.TryLoadStaticInstanceByFullName<IDummyInterfaceWithImplementationUsedForStaticTest>(out var staticInstance, fullName, counter);
-        TypeLoader.LoadStaticInstanceByFullName<IDummyInterfaceWithImplementationUsedForStaticTest>(fullName, counter);
+        TypeLoader.TryLoadStaticInstanceByFullName(out staticInstance, fullName, counter);
 
         // Assert
-        result.Should().BeOfType<DummyClass2UsedForStaticTest>();
+        result.Should().BeTrue();
+        staticInstance.Should().BeOfType<DummyClass2UsedForStaticTest>();
         counter.Value.Should().Be(1);
     }
 
     [Fact]
-    public void LoadNewInstance_ButNoImplementationFoundForInterface_ThrowsException()
+    public void TryLoadNewInstance_ButNoImplementationFoundForInterface_ReturnsFalse()
     {
         // Act
-        Action a = () => TypeLoader.LoadNewInstance<IDummyInterfaceNoImplementation>();
+        var result = TypeLoader.TryLoadNewInstance<IDummyInterfaceNoImplementation>(out _);
 
         // Assert
-        a.Should().Throw<DllNotFoundException>().WithMessage("No dll found which implements Interface 'WireMock.Net.Tests.Util.TypeLoaderTests+IDummyInterfaceNoImplementation'.");
+        result.Should().BeFalse();
     }
 
     [Fact]
-    public void LoadNewInstanceByFullName_ButNoImplementationFoundForInterface_ThrowsException()
+    public void TryLoadNewInstanceByFullName_ButNoImplementationFoundForInterface_ReturnsFalse()
     {
         // Act
-        Action a = () => TypeLoader.LoadNewInstanceByFullName<IDummyInterfaceWithImplementation>("xyz");
+        var result = TypeLoader.TryLoadNewInstanceByFullName<IDummyInterfaceWithImplementation>(out _, "xyz");
 
         // Assert
-        a.Should().Throw<DllNotFoundException>().WithMessage("No dll found which implements Interface 'WireMock.Net.Tests.Util.TypeLoaderTests+IDummyInterfaceWithImplementation' and has FullName 'xyz'.");
+        result.Should().BeFalse();
     }
 }