Added interception for missing extension method event

src/ConfigurationProcessor.Core/ConfigurationExtensions.cs

@@ -43,41 +43,71 @@ public static TContext ProcessConfiguration<TContext>(
             throw new ArgumentNullException(nameof(configuration));
          }
 
+         configuration.ProcessConfiguration(
+             context,
+             options =>
+             {
+                options.ConfigSection = configSection;
+                options.MethodFilterFactory = methodFilterFactory;
+                options.AdditionalMethods = additionalMethods;
+                options.ContextPaths = contextPaths;
+             });
+         return context;
+      }
+
+      /// <summary>
+      /// Processes the configuration.
+      /// </summary>
+      /// <typeparam name="TContext">The object type that is transformed by the configuration.</typeparam>
+      /// <param name="configuration">The configuration object.</param>
+      /// <param name="context">The object that is processed by the configuration.</param>
+      /// <param name="configureOptions">The configuration reader options builder.</param>
+      /// <returns>The <paramref name="context"/> object for chaining.</returns>
+      /// <exception cref="ArgumentNullException">Thrown when <paramref name="configuration"/> is null.</exception>
+      public static TContext ProcessConfiguration<TContext>(
+          this IConfiguration configuration,
+          TContext context,
+          Action<ConfigurationReaderOptions> configureOptions)
+          where TContext : class
+      {
+         if (configuration == null)
+         {
+            throw new ArgumentNullException(nameof(configuration));
+         }
+
          context.AddFromConfiguration(
              configuration,
-             configuration.GetSection(configSection),
-             contextPaths ?? new string?[] { string.Empty },
-             methodFilterFactory,
-             additionalMethods ?? Array.Empty<MethodInfo>(),
-             AssemblyFinder.Auto());
+             AssemblyFinder.Auto(),
+             configureOptions);
          return context;
       }
 
       internal static TConfig AddFromConfiguration<TConfig>(
           this TConfig builder,
           IConfiguration rootConfiguration,
-          IConfigurationSection configurationSection,
-          string?[] servicePaths,
-          MethodFilterFactory? methodFilterFactory,
-          MethodInfo[] additionalMethods,
-          AssemblyFinder assemblyFinder)
+          AssemblyFinder assemblyFinder,
+          Action<ConfigurationReaderOptions> configureOptions)
           where TConfig : class
       {
-         var reader = new ConfigurationReader<TConfig>(rootConfiguration, configurationSection, assemblyFinder, additionalMethods);
+         var options = new ConfigurationReaderOptions();
+         configureOptions?.Invoke(options);
+         var configurationSection = rootConfiguration.GetSection(options.ConfigSection);
+
+         var reader = new ConfigurationReader<TConfig>(rootConfiguration, configurationSection, assemblyFinder, options);
 
-         foreach (var servicePath in servicePaths)
+         foreach (var servicePath in options.ContextPaths ?? new string?[] { string.Empty })
          {
             if (string.IsNullOrEmpty(servicePath))
             {
-               reader.AddServices(builder, null, true, methodFilterFactory);
+               reader.AddServices(builder, null, true, options);
             }
             else if (servicePath![0] == '^')
             {
-               reader.AddServices(builder, servicePath.Substring(1), false, methodFilterFactory);
+               reader.AddServices(builder, servicePath.Substring(1), false, options);
             }
             else
             {
-               reader.AddServices(builder, servicePath, true, methodFilterFactory);
+               reader.AddServices(builder, servicePath, true, options);
             }
          }
 

src/ConfigurationProcessor.Core/ConfigurationReaderOptions.cs

@@ -0,0 +1,41 @@
+// -------------------------------------------------------------------------------------------------
+// Copyright (c) almostchristian. All rights reserved.
+// -------------------------------------------------------------------------------------------------
+
+using System;
+using System.Reflection;
+using ConfigurationProcessor.Core.Implementation;
+
+namespace ConfigurationProcessor.Core
+{
+   /// <summary>
+   /// Configuration reader options.
+   /// </summary>
+   public class ConfigurationReaderOptions
+   {
+      /// <summary>
+      /// Gets the config section.
+      /// </summary>
+      public string ConfigSection { get; set; } = "Services";
+
+      /// <summary>
+      /// Gets the context paths.
+      /// </summary>
+      public string[]? ContextPaths { get; set; }
+
+      /// <summary>
+      /// Gets ths method filter factory.
+      /// </summary>
+      public MethodFilterFactory? MethodFilterFactory { get; set; }
+
+      /// <summary>
+      /// Additional methods.
+      /// </summary>
+      public MethodInfo[]? AdditionalMethods { get; set; }
+
+      /// <summary>
+      /// Gets or sets the method to invoke when a method is not found. The default method throws a <see cref="MissingMethodException"/>.
+      /// </summary>
+      public Action<ExtensionMethodNotFoundEventArgs> OnExtensionMethodNotFound { get; set; } = x => { };
+   }
+}

src/ConfigurationProcessor.Core/ExtensionMethodNotFoundEventArgs.cs

@@ -0,0 +1,54 @@
+// -------------------------------------------------------------------------------------------------
+// Copyright (c) almostchristian. All rights reserved.
+// -------------------------------------------------------------------------------------------------
+
+using System;
+using System.Collections.Generic;
+using System.Reflection;
+using Microsoft.Extensions.Configuration;
+
+namespace ConfigurationProcessor.Core
+{
+   /// <summary>
+   /// Represents event data when an extension method was not found.
+   /// </summary>
+   public class ExtensionMethodNotFoundEventArgs : EventArgs
+   {
+      internal ExtensionMethodNotFoundEventArgs(
+         IEnumerable<MethodInfo> candidateMethods,
+         IEnumerable<string> candidateNames,
+         Type extensionMethodType,
+         IReadOnlyDictionary<string, IConfigurationSection> suppliedArguments)
+      {
+         CandidateMethods = candidateMethods;
+         CandidateNames = candidateNames;
+         ExtensionMethodType = extensionMethodType;
+         SuppliedArguments = suppliedArguments;
+      }
+
+      /// <summary>
+      /// Gets the candidate methods.
+      /// </summary>
+      public IEnumerable<MethodInfo> CandidateMethods { get; }
+
+      /// <summary>
+      /// Gets the candidate method names.
+      /// </summary>
+      public IEnumerable<string> CandidateNames { get; }
+
+      /// <summary>
+      /// Gets the extension method type that was searched.
+      /// </summary>
+      public Type ExtensionMethodType { get; }
+
+      /// <summary>
+      /// Gets the supplied argument names.
+      /// </summary>
+      public IReadOnlyDictionary<string, IConfigurationSection> SuppliedArguments { get; }
+
+      /// <summary>
+      /// Gets or sets if the event is handled. If true, an exception will not be thrown.
+      /// </summary>
+      public bool Handled { get; set; }
+   }
+}

src/ConfigurationProcessor.Core/Implementation/ConfigurationReader{TConfig}.cs

@@ -2,6 +2,7 @@
 // Copyright (c) almostchristian. All rights reserved.
 // -------------------------------------------------------------------------------------------------
 
+using System;
 using System.Linq;
 using System.Reflection;
 using ConfigurationProcessor.Core.Assemblies;
@@ -12,12 +13,12 @@ namespace ConfigurationProcessor.Core.Implementation
    internal class ConfigurationReader<TConfig> : ConfigurationReader, IConfigurationReader<TConfig>
         where TConfig : class
    {
-      public ConfigurationReader(IConfiguration configuration, IConfigurationSection configSection, AssemblyFinder assemblyFinder, MethodInfo[] additionalMethods)
-          : base(new ResolutionContext(assemblyFinder, configuration, configSection, additionalMethods, typeof(TConfig)), configuration, assemblyFinder, configSection)
+      public ConfigurationReader(IConfiguration configuration, IConfigurationSection configSection, AssemblyFinder assemblyFinder, ConfigurationReaderOptions options)
+          : base(new ResolutionContext(assemblyFinder, configuration, configSection, options.AdditionalMethods ?? Array.Empty<MethodInfo>(), options.OnExtensionMethodNotFound, typeof(TConfig)), configuration, assemblyFinder, configSection)
       {
       }
 
-      public void AddServices(TConfig builder, string? sectionName, bool getChildren, MethodFilterFactory? methodFilterFactory)
+      public void AddServices(TConfig builder, string? sectionName, bool getChildren, ConfigurationReaderOptions options)
       {
          var builderDirective = string.IsNullOrEmpty(sectionName) ? ConfigurationSection : ConfigurationSection.GetSection(sectionName);
          if (!getChildren || builderDirective.GetChildren().Any())
@@ -26,7 +27,7 @@ public void AddServices(TConfig builder, string? sectionName, bool getChildren,
             ResolutionContext.CallConfigurationMethods(
                typeof(TConfig),
                methodCalls,
-               methodFilterFactory,
+               options.MethodFilterFactory,
                (arguments, methodInfo) =>
                {
                   if (methodInfo.IsStatic)

src/ConfigurationProcessor.Core/Implementation/Extensions.cs

@@ -114,30 +114,44 @@ public static void CallConfigurationMethods(
             {
                if (!configurationMethods.Any())
                {
-                  var allExtensionMethods = resolutionContext
+                  configurationMethods = resolutionContext
                      .FindConfigurationExtensionMethods(methodName, extensionArgumentType, typeArgs, null, null)
-                     .Select(x => x.Name).Distinct();
-
-                  throw new MissingMethodException($"Unable to find methods called \"{string.Join(", ", candidateNames)}\" for type '{extensionArgumentType}'. Extension method names for type are:{Environment.NewLine}{string.Join(Environment.NewLine, allExtensionMethods)}");
+                     .Distinct();
                }
-               else
+
+               var errorEventArgs = new ExtensionMethodNotFoundEventArgs(
+                  configurationMethods,
+                  candidateNames,
+                  extensionArgumentType,
+                  paramArgs.ToDictionary(x => x.Key, x => x.Value.ConfigSection));
+
+               resolutionContext.OnExtensionMethodNotFound(errorEventArgs);
+
+               if (!errorEventArgs.Handled)
                {
-                  var methodsByName = configurationMethods
-                      .Select(m => $"{m.Name}({string.Join(", ", m.GetParameters().Skip(1).Select(p => p.Name))})")
-                      .ToList();
-
-                  throw new MissingMethodException($"Unable to find methods called \"{string.Join(", ", candidateNames)}\" for type '{extensionArgumentType}' "
-                  + (suppliedArgumentNames.Any()
-                      ? "for supplied named arguments: " + string.Join(", ", suppliedArgumentNames)
-                      : "with no supplied arguments")
-                  + ". Candidate methods are:"
-                  + Environment.NewLine
-                  + string.Join(Environment.NewLine, methodsByName));
+                  ThrowMissingMethodException(errorEventArgs);
                }
             }
          }
       }
 
+      private static void ThrowMissingMethodException(ExtensionMethodNotFoundEventArgs args)
+      {
+         string message;
+         var methods = args.CandidateMethods
+                   .Select(m => $"{m.Name}({string.Join(", ", m.GetParameters().Skip(1).Select(p => p.Name))})")
+                   .ToList();
+         message = $"Unable to find methods called \"{string.Join(", ", args.CandidateNames)}\" for type '{args.ExtensionMethodType}' "
+               + (args.SuppliedArguments.Any()
+                   ? "for supplied named arguments: " + string.Join(", ", args.SuppliedArguments.Keys)
+                   : "with no supplied arguments")
+               + ". Candidate methods are:"
+               + Environment.NewLine
+               + string.Join(Environment.NewLine, methods);
+
+         throw new MissingMethodException(message);
+      }
+
       private static List<MethodInfo> FindConfigurationExtensionMethods(
           this ResolutionContext resolutionContext,
           string key,
@@ -335,7 +349,7 @@ private static Delegate GenerateLambda(
          {
             var methodExpressions = new List<Expression>();
 
-            var childResolutionContext = new ResolutionContext(resolutionContext.AssemblyFinder, resolutionContext.RootConfiguration, sourceConfigurationSection, resolutionContext.AdditionalMethods, argumentType);
+            var childResolutionContext = new ResolutionContext(resolutionContext.AssemblyFinder, resolutionContext.RootConfiguration, sourceConfigurationSection, resolutionContext.AdditionalMethods, resolutionContext.OnExtensionMethodNotFound, argumentType);
 
             var keysToExclude = new List<string> { originalKey };
             if (int.TryParse(sourceConfigurationSection.Key, out _))

src/ConfigurationProcessor.Core/Implementation/IConfigurationReader.cs

@@ -7,6 +7,6 @@ namespace ConfigurationProcessor.Core.Implementation
    internal interface IConfigurationReader<in TConfig>
         where TConfig : class
    {
-      void AddServices(TConfig builder, string? sectionName, bool getChildren, MethodFilterFactory methodFilterFactory);
+      void AddServices(TConfig builder, string? sectionName, bool getChildren, ConfigurationReaderOptions options);
    }
 }

src/ConfigurationProcessor.Core/Implementation/ResolutionContext.cs

@@ -27,6 +27,7 @@ public ResolutionContext(
          IConfiguration rootConfiguration,
          IConfigurationSection appConfiguration,
          MethodInfo[] additionalMethods,
+         Action<ExtensionMethodNotFoundEventArgs> onExtensionMethodNotFound,
          params Type[] markerTypes)
       {
          if (assemblyFinder != null && appConfiguration != null)
@@ -38,12 +39,15 @@ public ResolutionContext(
             ConfigurationAssemblies = new List<Assembly>();
          }
 
+         OnExtensionMethodNotFound = onExtensionMethodNotFound;
          this.appConfiguration = appConfiguration;
          this.rootConfiguration = rootConfiguration;
          AssemblyFinder = assemblyFinder!;
          AdditionalMethods = additionalMethods;
       }
 
+      public Action<ExtensionMethodNotFoundEventArgs> OnExtensionMethodNotFound { get; }
+
       public MethodInfo[] AdditionalMethods { get; }
 
       public AssemblyFinder AssemblyFinder { get; }

src/ConfigurationProcessor.DependencyInjection/ConfigurationProcessorServiceCollectionExtensions.cs

@@ -71,6 +71,26 @@ public static IServiceCollection AddFromConfiguration(
           string[]? servicePaths,
           MethodFilterFactory? methodFilterFactory,
           MethodInfo[]? additionalMethods = null)
+         => services.AddFromConfiguration(configuration, options =>
+         {
+            options.ConfigSection = servicesSection;
+            options.ContextPaths = servicePaths;
+            options.MethodFilterFactory = methodFilterFactory;
+            options.AdditionalMethods = additionalMethods;
+         });
+
+      /// <summary>
+      /// Adds services from configuration.
+      /// </summary>
+      /// <param name="services">The service collection.</param>
+      /// <param name="configuration">The configuration to read from.</param>
+      /// <param name="configureOptions">The config options.</param>
+      /// <returns>The service collection for chaining.</returns>
+      /// <exception cref="ArgumentNullException">Thrown when <paramref name="configuration"/> is null.</exception>
+      public static IServiceCollection AddFromConfiguration(
+          this IServiceCollection services,
+          IConfiguration configuration,
+          Action<ConfigurationReaderOptions> configureOptions)
       {
          if (configuration == null)
          {
@@ -79,10 +99,7 @@ public static IServiceCollection AddFromConfiguration(
 
          return configuration.ProcessConfiguration(
              services,
-             servicesSection,
-             servicePaths,
-             methodFilterFactory,
-             additionalMethods);
+             configureOptions);
       }
    }
 }

src/Directory.Build.props

@@ -5,7 +5,7 @@
    </PropertyGroup>
 
    <PropertyGroup>
-      <Version>1.1.1</Version>
+      <Version>1.2.0</Version>
       <FileVersion>$(Version).$([System.DateTime]::Now.ToString(yy))$([System.DateTime]::Now.DayOfYear.ToString(000))</FileVersion>
       <PackageVersion>$(Version)</PackageVersion>
       <InformationalVersion>$(FileVersion)-$(GIT_VERSION)</InformationalVersion>
@@ -23,6 +23,8 @@
       <PackageTags>dependencyinjection;configuration;ioc;di;</PackageTags>
       <PackageReadmeFile>README.md</PackageReadmeFile>
       <PackageReleaseNotes>
+v1.2.0
+   - Added interception for missing extension method event
 v1.1.1
    - Ignore TypeLoadException when scanning for extension methods
 v1.1.0