Another test and exception message

Author: pakrym

src/Microsoft.Extensions.DependencyInjection/Properties/Resources.Designer.cs

@@ -147,4 +147,7 @@
   <data name="ScopedResolvedFromRootException" xml:space="preserve">
     <value>Cannot resolve '{0}' from root provider because it requires {2} service '{1}'.</value>
   </data>
+  <data name="DirectScopedResolvedFromRootException" xml:space="preserve">
+    <value>Cannot resolve {1} service '{0}' from root provider.</value>
+  </data>
 </root>

src/Microsoft.Extensions.DependencyInjection/Resources.resx

@@ -11,7 +11,8 @@ public static class ServiceCollectionContainerBuilderExtensions
         /// Creates an <see cref="IServiceProvider"/> containing services from the provided <see cref="IServiceCollection"/>.
         /// </summary>
         /// <param name="services">The <see cref="IServiceCollection"/> containing service descriptors.</param>
-        /// <returns>An instance of <see cref="IServiceProvider"/> providing access to services.</returns>
+        /// <returns>The<see cref="IServiceProvider"/>.</returns>
+
         public static IServiceProvider BuildServiceProvider(this IServiceCollection services)
         {
             return BuildServiceProvider(services, validateScopes: false);
@@ -25,7 +26,7 @@ public static IServiceProvider BuildServiceProvider(this IServiceCollection serv
         /// <param name="validateScopes">
         /// <c>true</c> to perform check verifying that scoped services never gets resolved from root provider; otherwise <c>false</c>.
         /// </param>
-        /// <returns>An instance of <see cref="IServiceProvider"/> providing access to services.</returns>
+        /// <returns>The<see cref="IServiceProvider"/>.</returns>
         public static IServiceProvider BuildServiceProvider(this IServiceCollection services, bool validateScopes)
         {
             return new ServiceProvider(services, validateScopes);

src/Microsoft.Extensions.DependencyInjection/ServiceCollectionContainerBuilderExtensions.cs

@@ -8,6 +8,7 @@ namespace Microsoft.Extensions.DependencyInjection.ServiceLookup
 {
     internal class CallSiteValidator: CallSiteVisitor<CallSiteValidator.CallSiteValidatorState, Type>
     {
+        // Keys are services being resolved via GetService, values - first scoped service in their call site tree
         private readonly Dictionary<Type, Type> _scopedServices = new Dictionary<Type, Type>();
 
         public void ValidateCallSite(Type serviceType, IServiceCallSite callSite)
@@ -25,10 +26,18 @@ public void ValidateResolution(Type serviceType, ServiceProvider serviceProvider
             if (ReferenceEquals(serviceProvider, serviceProvider.Root)
                 && _scopedServices.TryGetValue(serviceType, out scopedService))
             {
-                throw new InvalidOperationException(Resources.FormatScopedResolvedFromRootException(
-                    serviceType,
-                    scopedService,
-                    nameof(ServiceLifetime.Scoped).ToLowerInvariant()));
+                if (serviceType == scopedService)
+                {
+                    throw new InvalidOperationException(
+                        Resources.FormatDirectScopedResolvedFromRootException(serviceType,
+                            nameof(ServiceLifetime.Scoped).ToLowerInvariant()));
+                }
+
+                throw new InvalidOperationException(
+                    Resources.FormatScopedResolvedFromRootException(
+                        serviceType,
+                        scopedService,
+                        nameof(ServiceLifetime.Scoped).ToLowerInvariant()));
             }
         }
 

src/Microsoft.Extensions.DependencyInjection/ServiceLookup/CallSiteValidator.cs

@@ -54,6 +54,19 @@ public void GetService_Throws_WhenScopedIsInjectedIntoSingletonThroughSingleton(
 
         [Fact]
         public void GetService_Throws_WhenGetServiceForScopedServiceIsCalledOnRoot()
+        {
+            // Arrange
+            var serviceCollection = new ServiceCollection();
+            serviceCollection.AddScoped<IBar, Bar>();
+            var serviceProvider = serviceCollection.BuildServiceProvider(validateScopes: true);
+
+            // Act + Assert
+            var exception = Assert.Throws<InvalidOperationException>(() => serviceProvider.GetService(typeof(IBar)));
+            Assert.Equal($"Cannot resolve scoped service '{typeof(IBar)}' from root provider.", exception.Message);
+        }
+
+        [Fact]
+        public void GetService_Throws_WhenGetServiceForScopedServiceIsCalledOnRootViaTransient()
         {
             // Arrange
             var serviceCollection = new ServiceCollection();
@@ -67,7 +80,6 @@ public void GetService_Throws_WhenGetServiceForScopedServiceIsCalledOnRoot()
         }
 
         [Fact]
-
         public void GetService_DoesNotThrow_WhenScopeFactoryIsInjectedIntoSingleton()
         {
             // Arrange