Fixes #76 - improve error messages in Hosting

Removed the TODOs from messages, and generally made them more readable.

Author: Eilon Lipton

src/Microsoft.AspNet.Hosting/Program.cs

@@ -67,7 +67,7 @@ public void Main(string[] args)
                 catch (Exception ex)
                 {
                     var logger = loggerFactory.Create<Program>();
-                    logger.WriteError("TODO: Dispose threw an exception", ex);
+                    logger.WriteError("Dispose threw an exception.", ex);
                 }
                 shutdownHandle.Set();
             });

src/Microsoft.AspNet.Hosting/Server/ServerLoader.cs

@@ -32,7 +32,7 @@ public IServerFactory LoadServerFactory(string serverFactoryIdentifier)
             var assembly = Assembly.Load(new AssemblyName(assemblyName));
             if (assembly == null)
             {
-                throw new Exception(String.Format("TODO: assembly {0} failed to load message", assemblyName));
+                throw new Exception(string.Format("The assembly {0} failed to load.", assemblyName));
             }
 
             Type type = null;
@@ -50,7 +50,7 @@ public IServerFactory LoadServerFactory(string serverFactoryIdentifier)
 
                 if (type == null)
                 {
-                    throw new Exception(String.Format("TODO: type {0} failed to load message", typeName ?? "<null>"));
+                    throw new Exception(string.Format("The type {0} failed to load.", typeName ?? "<null>"));
                 }
             }
             else
@@ -59,14 +59,14 @@ public IServerFactory LoadServerFactory(string serverFactoryIdentifier)
 
                 if (type == null)
                 {
-                    throw new Exception(String.Format("TODO: type {0} failed to load message", typeName ?? "<null>"));
+                    throw new Exception(String.Format("The type {0} failed to load.", typeName ?? "<null>"));
                 }
 
                 interfaceInfo = type.GetTypeInfo().ImplementedInterfaces.FirstOrDefault(interf => interf.Equals(typeof(IServerFactory)));
 
                 if (interfaceInfo == null)
                 {
-                    throw new Exception("TODO: IServerFactory interface not found");
+                    throw new Exception(string.Format("The type '{0}' does not implement the '{1}' interface.", type, typeof(IServerFactory).FullName));
                 }
             }
 

src/Microsoft.AspNet.Hosting/Startup/StartupLoader.cs

@@ -31,9 +31,10 @@ private MethodInfo FindMethod(Type startupType, string methodName, string enviro
             {
                 if (required)
                 {
-                    throw new Exception(string.Format("TODO: {0} or {1} method not found",
+                    throw new Exception(string.Format("A method named '{0}' or '{1}' in the type '{2}' could not be found.",
                         methodNameWithEnv,
-                        methodNameWithNoEnv));
+                        methodNameWithNoEnv,
+                        startupType.FullName));
 
                 }
                 return null;
@@ -42,8 +43,10 @@ private MethodInfo FindMethod(Type startupType, string methodName, string enviro
             {
                 if (required)
                 {
-                    throw new Exception(string.Format("TODO: {0} method does not return " + returnType.Name,
-                        methodInfo.Name));
+                    throw new Exception(string.Format("The '{0}' method in the type '{1}' must have a return type of '{2}'.",
+                        methodInfo.Name,
+                        startupType.FullName,
+                        returnType.Name));
                 }
                 return null;
             }
@@ -75,10 +78,11 @@ private object Invoke(MethodInfo methodInfo, object instance, IApplicationBuilde
                     catch (Exception)
                     {
                         throw new Exception(string.Format(
-                            "TODO: Unable to resolve service for {0} method {1} {2}",
-                            methodInfo.Name,
+                            "Could not resolve a service of type '{0}' for the parameter '{1}' of method '{2}' on type '{3}'.",
+                            parameterInfo.ParameterType.FullName,
                             parameterInfo.Name,
-                            parameterInfo.ParameterType.FullName));
+                            methodInfo.Name,
+                            methodInfo.DeclaringType.FullName));
                     }
                 }
             }
@@ -98,26 +102,26 @@ public Action<IApplicationBuilder> LoadStartup(
             var assembly = Assembly.Load(new AssemblyName(applicationName));
             if (assembly == null)
             {
-                throw new Exception(String.Format("TODO: assembly {0} failed to load message", applicationName));
+                throw new Exception(String.Format("The assembly '{0}' failed to load.", applicationName));
             }
 
-            var startupName1 = "Startup" + environmentName;
-            var startupName2 = "Startup";
+            var startupNameWithEnv = "Startup" + environmentName;
+            var startupNameWithoutEnv = "Startup";
 
             // Check the most likely places first
             var type =
-                assembly.GetType(startupName1) ??
-                assembly.GetType(applicationName + "." + startupName1) ??
-                assembly.GetType(startupName2) ??
-                assembly.GetType(applicationName + "." + startupName2);
+                assembly.GetType(startupNameWithEnv) ??
+                assembly.GetType(applicationName + "." + startupNameWithEnv) ??
+                assembly.GetType(startupNameWithoutEnv) ??
+                assembly.GetType(applicationName + "." + startupNameWithoutEnv);
 
             if (type == null)
             {
                 // Full scan
                 var definedTypes = assembly.DefinedTypes.ToList();
 
-                var startupType1 = definedTypes.Where(info => info.Name.Equals(startupName1, StringComparison.Ordinal));
-                var startupType2 = definedTypes.Where(info => info.Name.Equals(startupName2, StringComparison.Ordinal));
+                var startupType1 = definedTypes.Where(info => info.Name.Equals(startupNameWithEnv, StringComparison.Ordinal));
+                var startupType2 = definedTypes.Where(info => info.Name.Equals(startupNameWithoutEnv, StringComparison.Ordinal));
 
                 var typeInfo = startupType1.Concat(startupType2).FirstOrDefault();
                 if (typeInfo != null)
@@ -128,9 +132,9 @@ public Action<IApplicationBuilder> LoadStartup(
 
             if (type == null)
             {
-                throw new Exception(String.Format("TODO: {0} or {1} class not found in assembly {2}",
-                    startupName1,
-                    startupName2,
+                throw new Exception(String.Format("A type named '{0}' or '{1}' could not be found in assembly '{2}'.",
+                    startupNameWithEnv,
+                    startupNameWithoutEnv,
                     applicationName));
             }
 

test/Microsoft.AspNet.Hosting.Tests/Fakes/StartupWithConfigureServicesNotResolved.cs

@@ -0,0 +1,18 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.AspNet.Builder;
+
+namespace Microsoft.AspNet.Hosting.Fakes
+{
+    public class StartupWithConfigureServicesNotResolved
+    {
+        public StartupWithConfigureServicesNotResolved()
+        {
+        }
+
+        public void Configure(IApplicationBuilder builder, int notAService)
+        {
+        }
+    }
+}

test/Microsoft.AspNet.Hosting.Tests/StartupManagerTests.cs

@@ -114,7 +114,25 @@ public void StartupWithNoConfigureThrows()
             var diagnosticMessages = new List<string>();
 
             var ex = Assert.Throws<Exception>(() => loader.LoadStartup("Microsoft.AspNet.Hosting.Tests", "Boom", diagnosticMessages));
-            Assert.True(ex.Message.Contains("ConfigureBoom or Configure method not found"));
+            Assert.Equal("A method named 'ConfigureBoom' or 'Configure' in the type 'Microsoft.AspNet.Hosting.Fakes.StartupBoom' could not be found.", ex.Message);
+        }
+
+        [Fact]
+        public void StartupWithConfigureServicesNotResolvedThrows()
+        {
+            var serviceCollection = HostingServices.Create();
+            var services = serviceCollection.BuildServiceProvider();
+            var loader = services.GetRequiredService<IStartupLoader>();
+            var diagnosticMessages = new List<string>();
+
+            var startup = loader.LoadStartup("Microsoft.AspNet.Hosting.Tests", "WithConfigureServicesNotResolved", diagnosticMessages);
+
+
+            var app = new ApplicationBuilder(services);
+
+            var ex = Assert.Throws<Exception>(() => startup.Invoke(app));
+
+            Assert.Equal("Could not resolve a service of type 'System.Int32' for the parameter 'notAService' of method 'Configure' on type 'Microsoft.AspNet.Hosting.Fakes.StartupWithConfigureServicesNotResolved'.", ex.Message);
         }
 
         [Fact]