Updates for WebHostBuilderContext overloads

src/Microsoft.AspNetCore.Hosting.Abstractions/HostingAbstractionsWebHostBuilderExtensions.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Linq;
 using System.Threading;
-using System.Threading.Tasks;
 using Microsoft.AspNetCore.Hosting.Server;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;

src/Microsoft.AspNetCore.Hosting.Abstractions/IWebHostBuilder.cs

@@ -13,40 +13,21 @@ namespace Microsoft.AspNetCore.Hosting
     /// </summary>
     public interface IWebHostBuilder
     {
-        /// <summary>
-        /// The <see cref="WebHostBuilderContext"/> used during building.
-        /// </summary>
-        /// <remarks>
-        /// Some properties of this type will be null whilst it is being built, most noteably the <see cref="ILoggerFactory"/> will
-        /// be null inside the <see cref="ConfigureAppConfiguration(Action{WebHostBuilderContext, IConfigurationBuilder})"/> method.
-        /// </remarks>
-        WebHostBuilderContext Context { get; }
-
         /// <summary>
         /// Builds an <see cref="IWebHost"/> which hosts a web application.
         /// </summary>
         IWebHost Build();
 
         /// <summary>
-        /// Specify the <see cref="ILoggerFactory"/> to be used by the web host.
+        /// Adds a delegate for configuring the <see cref="IConfigurationBuilder"/> that will construct an <see cref="IConfiguration"/>.
         /// </summary>
-        /// <param name="loggerFactory">The <see cref="ILoggerFactory"/> to be used.</param>
+        /// <param name="configureDelegate">The delegate for configuring the <see cref="IConfigurationBuilder" /> that will be used to construct an <see cref="IConfiguration" />.</param>
         /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
-        IWebHostBuilder UseLoggerFactory(ILoggerFactory loggerFactory);
+        /// <remarks>
-
+        /// The <see cref="IConfiguration"/> and <see cref="ILoggerFactory"/> on the <see cref="WebHostBuilderContext"/> are uninitialized at this stage.
-        /// <summary>
+        /// The <see cref="IConfigurationBuilder"/> is pre-populated with the settings of the <see cref="IWebHostBuilder"/>.
-        /// Specify the delegate that is used to configure the services of the web application.
+        /// </remarks>
-        /// </summary>
+        IWebHostBuilder ConfigureAppConfiguration(Action<WebHostBuilderContext, IConfigurationBuilder> configureDelegate);
-        /// <param name="configureServices">The delegate that configures the <see cref="IServiceCollection"/>.</param>
-        /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
-        IWebHostBuilder ConfigureServices(Action<IServiceCollection> configureServices);
-
-        /// <summary>
-        /// Specify the delegate that is used to configure the services of the web application.
-        /// </summary>
-        /// <param name="configureServices">The delegate that configures the <see cref="IServiceCollection"/>.</param>
-        /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
-        IWebHostBuilder ConfigureServices(Action<WebHostBuilderContext, IServiceCollection> configureServices);
 
         /// <summary>
         /// Adds a delegate for configuring the provided <see cref="ILoggerFactory"/>. This may be called multiple times.
@@ -59,9 +40,39 @@ namespace Microsoft.AspNetCore.Hosting
         /// Adds a delegate for configuring the provided <see cref="ILoggerFactory"/>. This may be called multiple times.
         /// </summary>
         /// <param name="configureLogging">The delegate that configures the <see cref="ILoggerFactory"/>.</param>
+        /// <typeparam name="T">
+        /// The type of <see cref="ILoggerFactory"/> to configure.
+        /// The delegate will not execute if the type provided does not match the <see cref="ILoggerFactory"/> used by the <see cref="IWebHostBuilder"/>
+        /// </typeparam>
         /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
+        /// <remarks>
+        /// The <see cref="ILoggerFactory"/> on the <see cref="WebHostBuilderContext"/> is uninitialized at this stage.
+        /// </remarks>
         IWebHostBuilder ConfigureLogging<T>(Action<WebHostBuilderContext, T> configureLogging) where T : ILoggerFactory;
 
+        /// <summary>
+        /// Adds a delegate for configuring additional services for the host or web application. This may be called
+        /// multiple times.
+        /// </summary>
+        /// <param name="configureServices">A delegate for configuring the <see cref="IServiceCollection"/>.</param>
+        /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
+        IWebHostBuilder ConfigureServices(Action<IServiceCollection> configureServices);
+
+        /// <summary>
+        /// Adds a delegate for configuring additional services for the host or web application. This may be called
+        /// multiple times.
+        /// </summary>
+        /// <param name="configureServices">A delegate for configuring the <see cref="IServiceCollection"/>.</param>
+        /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
+        IWebHostBuilder ConfigureServices(Action<WebHostBuilderContext, IServiceCollection> configureServices);
+
+        /// <summary>
+        /// Get the setting value from the configuration.
+        /// </summary>
+        /// <param name="key">The key of the setting to look up.</param>
+        /// <returns>The value the setting currently contains.</returns>
+        string GetSetting(string key);
+
         /// <summary>
         /// Add or replace a setting in the configuration.
         /// </summary>
@@ -71,11 +82,11 @@ namespace Microsoft.AspNetCore.Hosting
         IWebHostBuilder UseSetting(string key, string value);
 
         /// <summary>
-        /// Get the setting value from the configuration.
+        /// Specify the <see cref="ILoggerFactory"/> to be used by the web host.
         /// </summary>
-        /// <param name="key">The key of the setting to look up.</param>
+        /// <param name="loggerFactory">The <see cref="ILoggerFactory"/> to be used.</param>
-        /// <returns>The value the setting currently contains.</returns>
+        /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
-        string GetSetting(string key);
+        IWebHostBuilder UseLoggerFactory(ILoggerFactory loggerFactory);
 
         /// <summary>
         /// Adds a delegate to construct the <see cref="ILoggerFactory"/> that will be registered
@@ -83,14 +94,9 @@ namespace Microsoft.AspNetCore.Hosting
         /// </summary>
         /// <param name="createLoggerFactory">The delegate that constructs an <see cref="IConfigurationBuilder" /></param>
         /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
+        /// <remarks>
+        /// The <see cref="ILoggerFactory"/> on the <see cref="WebHostBuilderContext"/> is uninitialized at this stage.
+        /// </remarks>
         IWebHostBuilder UseLoggerFactory(Func<WebHostBuilderContext, ILoggerFactory> createLoggerFactory);
-
-
-        /// <summary>
-        /// Adds a delegate for configuring the <see cref="IConfigurationBuilder"/> that will construct an <see cref="IConfiguration"/>.
-        /// </summary>
-        /// <param name="configureDelegate">The delegate for configuring the <see cref="IConfigurationBuilder" /> that will be used to construct an <see cref="IConfiguration" />.</param>
-        /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
-        IWebHostBuilder ConfigureAppConfiguration(Action<WebHostBuilderContext, IConfigurationBuilder> configureDelegate);
     }
 }

src/Microsoft.AspNetCore.Hosting.Abstractions/exceptions.net45.json

@@ -36,12 +36,6 @@
     "NewMemberId": "System.Threading.Tasks.Task StopAsync(System.Threading.CancellationToken cancellationToken)",
     "Kind": "Addition"
   },
-  {
-    "OldTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
-    "NewTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
-    "NewMemberId": "Microsoft.AspNetCore.Hosting.WebHostBuilderContext get_Context()",
-    "Kind": "Addition"
-  },
   {
     "OldTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
     "NewTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",

src/Microsoft.AspNetCore.Hosting.Abstractions/exceptions.netcore.json

@@ -36,12 +36,6 @@
     "NewMemberId": "System.Threading.Tasks.Task StopAsync(System.Threading.CancellationToken cancellationToken)",
     "Kind": "Addition"
   },
-  {
-    "OldTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
-    "NewTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
-    "NewMemberId": "Microsoft.AspNetCore.Hosting.WebHostBuilderContext get_Context()",
-    "Kind": "Addition"
-  },
   {
     "OldTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
     "NewTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",

src/Microsoft.AspNetCore.Hosting/WebHostBuilder.cs

@@ -30,12 +30,10 @@ namespace Microsoft.AspNetCore.Hosting
 
         private IConfiguration _config;
         private WebHostOptions _options;
+        private WebHostBuilderContext _context;
         private bool _webHostBuilt;
         private Func<WebHostBuilderContext, ILoggerFactory> _createLoggerFactoryDelegate;
-        private List<Action<WebHostBuilderContext, IConfigurationBuilder>> _configureConfigurationBuilderDelegates;
+        private List<Action<WebHostBuilderContext, IConfigurationBuilder>> _configureAppConfigurationBuilderDelegates;
-        private WebHostBuilderContext _hostingContext;
-
-        public WebHostBuilderContext Context { get { return _hostingContext; } }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="WebHostBuilder"/> class.
@@ -45,7 +43,7 @@ namespace Microsoft.AspNetCore.Hosting
             _hostingEnvironment = new HostingEnvironment();
             _configureServicesDelegates = new List<Action<WebHostBuilderContext, IServiceCollection>>();
             _configureLoggingDelegates = new List<Action<WebHostBuilderContext, ILoggerFactory>>();
-            _configureConfigurationBuilderDelegates = new List<Action<WebHostBuilderContext, IConfigurationBuilder>>();
+            _configureAppConfigurationBuilderDelegates = new List<Action<WebHostBuilderContext, IConfigurationBuilder>>();
 
             _config = new ConfigurationBuilder()
                 .AddEnvironmentVariables(prefix: "ASPNETCORE_")
@@ -63,6 +61,21 @@ namespace Microsoft.AspNetCore.Hosting
                 // Try adding legacy url key, never remove this.
                 UseSetting(WebHostDefaults.ServerUrlsKey, Environment.GetEnvironmentVariable("ASPNETCORE_SERVER.URLS"));
             }
+
+            _context = new WebHostBuilderContext
+            {
+                Configuration = _config
+            };
+        }
+
+        /// <summary>
+        /// Get the setting value from the configuration.
+        /// </summary>
+        /// <param name="key">The key of the setting to look up.</param>
+        /// <returns>The value the setting currently contains.</returns>
+        public string GetSetting(string key)
+        {
+            return _config[key];
         }
 
         /// <summary>
@@ -77,16 +90,6 @@ namespace Microsoft.AspNetCore.Hosting
             return this;
         }
 
-        /// <summary>
-        /// Get the setting value from the configuration.
-        /// </summary>
-        /// <param name="key">The key of the setting to look up.</param>
-        /// <returns>The value the setting currently contains.</returns>
-        public string GetSetting(string key)
-        {
-            return _config[key];
-        }
-
         /// <summary>
         /// Specify the <see cref="ILoggerFactory"/> to be used by the web host.
         /// </summary>
@@ -99,7 +102,26 @@ namespace Microsoft.AspNetCore.Hosting
                 throw new ArgumentNullException(nameof(loggerFactory));
             }
 
-            _createLoggerFactoryDelegate = _ => loggerFactory;
+            return UseLoggerFactory(_ => loggerFactory);
+        }
+
+        /// <summary>
+        /// Adds a delegate to construct the <see cref="ILoggerFactory"/> that will be registered
+        /// as a singleton and used by the application.
+        /// </summary>
+        /// <param name="createLoggerFactory">The delegate that constructs an <see cref="IConfigurationBuilder" /></param>
+        /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
+        /// <remarks>
+        /// The <see cref="ILoggerFactory"/> on the <see cref="WebHostBuilderContext"/> is uninitialized at this stage.
+        /// </remarks>
+        public IWebHostBuilder UseLoggerFactory(Func<WebHostBuilderContext, ILoggerFactory> createLoggerFactory)
+        {
+            if (createLoggerFactory == null)
+            {
+                throw new ArgumentNullException(nameof(createLoggerFactory));
+            }
+
+            _createLoggerFactoryDelegate = createLoggerFactory;
             return this;
         }
 
@@ -116,8 +138,7 @@ namespace Microsoft.AspNetCore.Hosting
                 throw new ArgumentNullException(nameof(configureServices));
             }
 
-            _configureServicesDelegates.Add((_, collection) => configureServices(collection));
+            return ConfigureServices((_ , services) => configureServices(services));
-            return this;
         }
 
         /// <summary>
@@ -153,34 +174,25 @@ namespace Microsoft.AspNetCore.Hosting
             return this;
         }
 
-        /// <summary>
-        /// Adds a delegate to construct the <see cref="ILoggerFactory"/> that will be registered
-        /// as a singleton and used by the application.
-        /// </summary>
-        /// <param name="createLoggerFactory">The delegate that constructs an <see cref="IConfigurationBuilder" /></param>
-        /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
-        public IWebHostBuilder UseLoggerFactory(Func<WebHostBuilderContext, ILoggerFactory> createLoggerFactory)
-        {
-            if (createLoggerFactory == null)
-            {
-                throw new ArgumentNullException(nameof(createLoggerFactory));
-            }
-
-            _createLoggerFactoryDelegate = createLoggerFactory;
-            return this;
-        }
-
         /// <summary>
         /// Adds a delegate for configuring the provided <see cref="ILoggerFactory"/>. This may be called multiple times.
         /// </summary>
         /// <param name="configureLogging">The delegate that configures the <see cref="ILoggerFactory"/>.</param>
+        /// <typeparam name="T">
+        /// The type of <see cref="ILoggerFactory"/> to configure.
+        /// The delegate will not execute if the type provided does not match the <see cref="ILoggerFactory"/> used by the <see cref="IWebHostBuilder"/>
+        /// </typeparam>
         /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
+        /// <remarks>
+        /// The <see cref="ILoggerFactory"/> on the <see cref="WebHostBuilderContext"/> is uninitialized at this stage.
+        /// </remarks>
         public IWebHostBuilder ConfigureLogging<T>(Action<WebHostBuilderContext, T> configureLogging) where T : ILoggerFactory
         {
             if (configureLogging == null)
             {
                 throw new ArgumentNullException(nameof(configureLogging));
             }
+
             _configureLoggingDelegates.Add((context, factory) =>
             {
                 if (factory is T typedFactory)
@@ -196,6 +208,10 @@ namespace Microsoft.AspNetCore.Hosting
         /// </summary>
         /// <param name="configureDelegate">The delegate for configuring the <see cref="IConfigurationBuilder" /> that will be used to construct an <see cref="IConfiguration" />.</param>
         /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
+        /// <remarks>
+        /// The <see cref="IConfiguration"/> and <see cref="ILoggerFactory"/> on the <see cref="WebHostBuilderContext"/> are uninitialized at this stage.
+        /// The <see cref="IConfigurationBuilder"/> is pre-populated with the settings of the <see cref="IWebHostBuilder"/>.
+        /// </remarks>
         public IWebHostBuilder ConfigureAppConfiguration(Action<WebHostBuilderContext, IConfigurationBuilder> configureDelegate)
         {
             if (configureDelegate == null)
@@ -203,7 +219,7 @@ namespace Microsoft.AspNetCore.Hosting
                 throw new ArgumentNullException(nameof(configureDelegate));
             }
 
-            _configureConfigurationBuilderDelegates.Add(configureDelegate);
+            _configureAppConfigurationBuilderDelegates.Add(configureDelegate);
             return this;
         }
 
@@ -262,35 +278,31 @@ namespace Microsoft.AspNetCore.Hosting
             var contentRootPath = ResolveContentRootPath(_options.ContentRootPath, appEnvironment.ApplicationBasePath);
             var applicationName = _options.ApplicationName ?? appEnvironment.ApplicationName;
 
-            _hostingContext = new WebHostBuilderContext
-            {
-                Configuration = _config
-            };
-
             // Initialize the hosting environment
             _hostingEnvironment.Initialize(applicationName, contentRootPath, _options);
-            _hostingContext.HostingEnvironment = _hostingEnvironment;
+            _context.HostingEnvironment = _hostingEnvironment;
 
             var services = new ServiceCollection();
             services.AddSingleton(_hostingEnvironment);
+            services.AddSingleton(_context);
 
             var builder = new ConfigurationBuilder()
                 .SetBasePath(_hostingEnvironment.ContentRootPath)
                 .AddInMemoryCollection(_config.AsEnumerable());
 
-            foreach (var configureConfiguration in _configureConfigurationBuilderDelegates)
+            foreach (var configureAppConfiguration in _configureAppConfigurationBuilderDelegates)
             {
-                configureConfiguration(_hostingContext, builder);
+                configureAppConfiguration(_context, builder);
             }
 
             var configuration = builder.Build();
             services.AddSingleton<IConfiguration>(configuration);
-            _hostingContext.Configuration = configuration;
+            _context.Configuration = configuration;
 
             // The configured ILoggerFactory is added as a singleton here. AddLogging below will not add an additional one.
-            var loggerFactory = _createLoggerFactoryDelegate?.Invoke(_hostingContext) ?? new LoggerFactory(configuration.GetSection("Logging"));
+            var loggerFactory = _createLoggerFactoryDelegate?.Invoke(_context) ?? new LoggerFactory(configuration.GetSection("Logging"));
             services.AddSingleton(loggerFactory);
-            _hostingContext.LoggerFactory = loggerFactory;
+            _context.LoggerFactory = loggerFactory;
 
             var exceptions = new List<Exception>();
 
@@ -325,10 +337,9 @@ namespace Microsoft.AspNetCore.Hosting
                 }
             }
 
-            // Kept for back-compat, will remove once ConfigureLogging is removed.
             foreach (var configureLogging in _configureLoggingDelegates)
             {
-                configureLogging(_hostingContext, loggerFactory);
+                configureLogging(_context, loggerFactory);
             }
 
             //This is required to add ILogger of T.
@@ -383,7 +394,7 @@ namespace Microsoft.AspNetCore.Hosting
 
             foreach (var configureServices in _configureServicesDelegates)
             {
-                configureServices(_hostingContext, services);
+                configureServices(_context, services);
             }
 
             return services;

src/Microsoft.AspNetCore.Hosting/WebHostBuilderExtensions.cs

@@ -28,7 +28,8 @@ namespace Microsoft.AspNetCore.Hosting
 
             var startupAssemblyName = configureApp.GetMethodInfo().DeclaringType.GetTypeInfo().Assembly.GetName().Name;
 
-            return hostBuilder.UseSetting(WebHostDefaults.ApplicationKey, startupAssemblyName)
+            return hostBuilder
+                .UseSetting(WebHostDefaults.ApplicationKey, startupAssemblyName)
                 .ConfigureServices(services =>
                 {
                     services.AddSingleton<IStartup>(sp =>
@@ -49,7 +50,8 @@ namespace Microsoft.AspNetCore.Hosting
         {
             var startupAssemblyName = startupType.GetTypeInfo().Assembly.GetName().Name;
 
-            return hostBuilder.UseSetting(WebHostDefaults.ApplicationKey, startupAssemblyName)
+            return hostBuilder
+                .UseSetting(WebHostDefaults.ApplicationKey, startupAssemblyName)
                 .ConfigureServices(services =>
                 {
                     if (typeof(IStartup).GetTypeInfo().IsAssignableFrom(startupType.GetTypeInfo()))
@@ -102,8 +104,7 @@ namespace Microsoft.AspNetCore.Hosting
         /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
         public static IWebHostBuilder ConfigureLogging(this IWebHostBuilder hostBuilder, Action<WebHostBuilderContext, LoggerFactory> configureLogging)
         {
-            hostBuilder.ConfigureLogging(configureLogging);
+            return hostBuilder.ConfigureLogging(configureLogging);
-            return hostBuilder;
         }
 
         /// <summary>
@@ -114,9 +115,7 @@ namespace Microsoft.AspNetCore.Hosting
         /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
         public static IWebHostBuilder ConfigureLogging<T>(this IWebHostBuilder hostBuilder, Action<T> configureLogging) where T : ILoggerFactory
         {
-            hostBuilder.ConfigureLogging<T>((_, factory) => configureLogging(factory));
+            return hostBuilder.ConfigureLogging<T>((_, factory) => configureLogging(factory));
-            return hostBuilder;
         }
-
     }
 }

test/Microsoft.AspNetCore.Hosting.Tests/WebHostBuilderTests.cs

@@ -35,19 +35,19 @@ namespace Microsoft.AspNetCore.Hosting
         {
             var builder = CreateWebHostBuilder().UseServer(new TestServer());
 
-            var host = (WebHost)builder.UseStartup("MyStartupAssembly").Build();
+            using (var host = (WebHost)builder.UseStartup("MyStartupAssembly").Build())
-
+            {
                 Assert.Equal("MyStartupAssembly", host.Options.ApplicationName);
                 Assert.Equal("MyStartupAssembly", host.Options.StartupAssembly);
             }
+        }
 
         [Fact]
         public async Task StartupMissing_Fallback()
         {
             var builder = CreateWebHostBuilder();
             var server = new TestServer();
-            var host = builder.UseServer(server).UseStartup("MissingStartupAssembly").Build();
+            using (var host = builder.UseServer(server).UseStartup("MissingStartupAssembly").Build())
-            using (host)
             {
                 await host.StartAsync();
                 await AssertResponseContains(server.RequestDelegate, "MissingStartupAssembly");
@@ -158,10 +158,11 @@ namespace Microsoft.AspNetCore.Hosting
                 .UseServer(new TestServer())
                 .UseStartup<StartupNoServices>();
 
-            var host = (WebHost)hostBuilder.Build();
+            using (var host = (WebHost)hostBuilder.Build())
-
+            {
                 Assert.NotNull(host.Services.GetService<ILoggerFactory>());
             }
+        }
 
         [Fact]
         public void ConfigureDefaultServiceProvider()
@@ -195,10 +196,11 @@ namespace Microsoft.AspNetCore.Hosting
                 .UseServer(new TestServer())
                 .UseStartup<StartupNoServices>();
 
-            var host = (WebHost)hostBuilder.Build();
+            using (var host = (WebHost)hostBuilder.Build())
-
+            {
                 Assert.Same(loggerFactory, host.Services.GetService<ILoggerFactory>());
             }
+        }
 
         [Fact]
         public void MultipleConfigureLoggingInvokedInOrder()
@@ -216,9 +218,11 @@ namespace Microsoft.AspNetCore.Hosting
                 .UseServer(new TestServer())
                 .UseStartup<StartupNoServices>();
 
-            var host = (WebHost)hostBuilder.Build();
+            using (hostBuilder.Build())
+            {
                 Assert.Equal(2, callCount);
             }
+        }
 
         [Fact]
         public void UseLoggerFactoryDelegateIsHonored()
@@ -230,10 +234,11 @@ namespace Microsoft.AspNetCore.Hosting
                 .UseServer(new TestServer())
                 .UseStartup<StartupNoServices>();
 
-            var host = (WebHost)hostBuilder.Build();
+            using (var host = (WebHost)hostBuilder.Build())
-
+            {
                 Assert.Same(loggerFactory, host.Services.GetService<ILoggerFactory>());
             }
+        }
 
         [Fact]
         public void UseLoggerFactoryFuncAndConfigureLoggingCompose()
@@ -252,17 +257,19 @@ namespace Microsoft.AspNetCore.Hosting
                 })
                 .UseServer(new TestServer())
                 .UseStartup<StartupNoServices>();
-            var host = (WebHost)hostBuilder.Build();
+            using (var host = (WebHost)hostBuilder.Build())
+            {
                 Assert.Equal(2, callCount);
                 Assert.Same(loggerFactory, host.Services.GetService<ILoggerFactory>());
             }
+        }
 
         [Fact]
-        public void HostingContextCanBeUsed()
+        public void HostingContextContainsAppConfigurationDuringConfigureLogging()
         {
             var hostBuilder = new WebHostBuilder()
-                 .ConfigureAppConfiguration((context, configBuilder) => configBuilder
+                 .ConfigureAppConfiguration((context, configBuilder) =>
-                    .AddInMemoryCollection(
+                    configBuilder.AddInMemoryCollection(
                         new KeyValuePair<string, string>[]
                         {
                             new KeyValuePair<string, string>("key1", "value1")
@@ -274,10 +281,27 @@ namespace Microsoft.AspNetCore.Hosting
                  .UseServer(new TestServer())
                  .UseStartup<StartupNoServices>();
 
-            hostBuilder.Build();
+            using (hostBuilder.Build()) { }
+        }
 
-            //Verify property on builder is set.
+        [Fact]
-            Assert.Equal("value1", hostBuilder.Context.Configuration["key1"]);
+        public void HostingContextContainsAppConfigurationDuringConfigureServices()
+        {
+            var hostBuilder = new WebHostBuilder()
+                 .ConfigureAppConfiguration((context, configBuilder) =>
+                    configBuilder.AddInMemoryCollection(
+                        new KeyValuePair<string, string>[]
+                        {
+                            new KeyValuePair<string, string>("key1", "value1")
+                        }))
+                 .ConfigureServices((context, factory) =>
+                 {
+                     Assert.Equal("value1", context.Configuration["key1"]);
+                 })
+                 .UseServer(new TestServer())
+                 .UseStartup<StartupNoServices>();
+
+            using (hostBuilder.Build()) { }
         }
 
         [Fact]
@@ -293,9 +317,11 @@ namespace Microsoft.AspNetCore.Hosting
                 .UseServer(new TestServer())
                 .UseStartup<StartupNoServices>();
 
-            var host = (WebHost)hostBuilder.Build();
+            using (hostBuilder.Build())
+            {
                 Assert.Equal(1, callCount);
             }
+        }
 
         [Fact]
         public void ConfigureLoggingNotCalledIfLoggerFactoryTypeDoesNotMatches()
@@ -310,9 +336,11 @@ namespace Microsoft.AspNetCore.Hosting
                 .UseServer(new TestServer())
                 .UseStartup<StartupNoServices>();
 
-            var host = (WebHost)hostBuilder.Build();
+            using (hostBuilder.Build())
+            {
                 Assert.Equal(0, callCount);
             }
+        }
 
         [Fact]
         public void CanUseCustomLoggerFactory()
@@ -325,9 +353,12 @@ namespace Microsoft.AspNetCore.Hosting
                 })
                 .UseServer(new TestServer())
                 .UseStartup<StartupNoServices>();
-            var host = (WebHost)hostBuilder.Build();
+
+            using (var host = (WebHost)hostBuilder.Build())
+            {
                 Assert.IsType(typeof(CustomLoggerFactory), host.Services.GetService<ILoggerFactory>());
             }
+        }
 
         [Fact]
         public void ThereIsAlwaysConfiguration()
@@ -335,10 +366,12 @@ namespace Microsoft.AspNetCore.Hosting
             var hostBuilder = new WebHostBuilder()
                 .UseServer(new TestServer())
                 .UseStartup<StartupNoServices>();
-            var host = (WebHost)hostBuilder.Build();
 
+            using (var host = (WebHost)hostBuilder.Build())
+            {
                 Assert.NotNull(host.Services.GetService<IConfiguration>());
             }
+        }
 
         [Fact]
         public void ConfigureConfigurationSettingsPropagated()
@@ -352,7 +385,8 @@ namespace Microsoft.AspNetCore.Hosting
                 })
                 .UseServer(new TestServer())
                 .UseStartup<StartupNoServices>();
-            var host = (WebHost)hostBuilder.Build();
+
+            using (hostBuilder.Build()) { }
         }
 
         [Fact]
@@ -371,12 +405,14 @@ namespace Microsoft.AspNetCore.Hosting
                 })
                 .UseServer(new TestServer())
                 .UseStartup<StartupNoServices>();
-            var host = (WebHost)hostBuilder.Build();
 
+            using (var host = (WebHost)hostBuilder.Build())
+            {
                 var config = host.Services.GetService<IConfiguration>();
                 Assert.NotNull(config);
                 Assert.Equal("value1", config["key1"]);
             }
+        }
 
         [Fact]
         public void DoNotCaptureStartupErrorsByDefault()
@@ -419,12 +455,14 @@ namespace Microsoft.AspNetCore.Hosting
                 })
                 .Configure(app => { });
 
-            var host = hostBuilder.Build();
+            using (var host = hostBuilder.Build())
+            {
                 Assert.Equal(2, callCount);
 
                 Assert.NotNull(host.Services.GetRequiredService<ServiceA>());
                 Assert.NotNull(host.Services.GetRequiredService<ServiceB>());
             }
+        }
 
         [Fact]
         public void CodeBasedSettingsCodeBasedOverride()
@@ -435,10 +473,11 @@ namespace Microsoft.AspNetCore.Hosting
                 .UseServer(new TestServer())
                 .UseStartup<StartupNoServices>();
 
-            var host = (WebHost)hostBuilder.Build();
+            using (var host = (WebHost)hostBuilder.Build())
-
+            {
                 Assert.Equal("EnvB", host.Options.Environment);
             }
+        }
 
         [Fact]
         public void CodeBasedSettingsConfigBasedOverride()
@@ -458,10 +497,11 @@ namespace Microsoft.AspNetCore.Hosting
                 .UseServer(new TestServer())
                 .UseStartup<StartupNoServices>();
 
-            var host = (WebHost)hostBuilder.Build();
+            using (var host = (WebHost)hostBuilder.Build())
-
+            {
                 Assert.Equal("EnvB", host.Options.Environment);
             }
+        }
 
         [Fact]
         public void ConfigBasedSettingsCodeBasedOverride()
@@ -481,10 +521,11 @@ namespace Microsoft.AspNetCore.Hosting
                 .UseServer(new TestServer())
                 .UseStartup<StartupNoServices>();
 
-            var host = (WebHost)hostBuilder.Build();
+            using (var host = (WebHost)hostBuilder.Build())
-
+            {
                 Assert.Equal("EnvB", host.Options.Environment);
             }
+        }
 
         [Fact]
         public void ConfigBasedSettingsConfigBasedOverride()
@@ -513,10 +554,11 @@ namespace Microsoft.AspNetCore.Hosting
                 .UseServer(new TestServer())
                 .UseStartup<StartupNoServices>();
 
-            var host = (WebHost)hostBuilder.Build();
+            using (var host = (WebHost)hostBuilder.Build())
-
+            {
                 Assert.Equal("EnvB", host.Options.Environment);
             }
+        }
 
         [Fact]
         public void UseEnvironmentIsNotOverriden()
@@ -530,15 +572,18 @@ namespace Microsoft.AspNetCore.Hosting
             var config = builder.Build();
 
             var expected = "MY_TEST_ENVIRONMENT";
-            var host = new WebHostBuilder()
+
+
+            using (var host = new WebHostBuilder()
                 .UseConfiguration(config)
                 .UseEnvironment(expected)
                 .UseServer(new TestServer())
                 .UseStartup("Microsoft.AspNetCore.Hosting.Tests")
-                .Build();
+                .Build())
-
+            {
                 Assert.Equal(expected, host.Services.GetService<IHostingEnvironment>().EnvironmentName);
             }
+        }
 
         [Fact]
         public void BuildAndDispose()
@@ -552,14 +597,12 @@ namespace Microsoft.AspNetCore.Hosting
             var config = builder.Build();
 
             var expected = "MY_TEST_ENVIRONMENT";
-            var host = new WebHostBuilder()
+            using (var host = new WebHostBuilder()
                 .UseConfiguration(config)
                 .UseEnvironment(expected)
                 .UseServer(new TestServer())
                 .UseStartup("Microsoft.AspNetCore.Hosting.Tests")
-                .Build();
+                .Build()) { }
-
-            host.Dispose();
         }
 
         [Fact]
@@ -573,134 +616,142 @@ namespace Microsoft.AspNetCore.Hosting
                 .AddInMemoryCollection(vals);
             var config = builder.Build();
 
-            var host = new WebHostBuilder()
+            using (var host = new WebHostBuilder()
                 .UseConfiguration(config)
                 .UseContentRoot("/")
                 .UseServer(new TestServer())
                 .UseStartup("Microsoft.AspNetCore.Hosting.Tests")
-                .Build();
+                .Build())
-
+            {
                 Assert.Equal("/", host.Services.GetService<IHostingEnvironment>().ContentRootPath);
             }
+        }
 
         [Fact]
         public void RelativeContentRootIsResolved()
         {
-            var host = new WebHostBuilder()
+            using (var host = new WebHostBuilder()
                 .UseContentRoot("testroot")
                 .UseServer(new TestServer())
                 .UseStartup("Microsoft.AspNetCore.Hosting.Tests")
-                .Build();
+                .Build())
-
+            {
                 var basePath = host.Services.GetRequiredService<IHostingEnvironment>().ContentRootPath;
                 Assert.True(Path.IsPathRooted(basePath));
                 Assert.EndsWith(Path.DirectorySeparatorChar + "testroot", basePath);
             }
+        }
 
         [Fact]
         public void DefaultContentRootIsApplicationBasePath()
         {
-            var host = new WebHostBuilder()
+            using (var host = new WebHostBuilder()
                 .UseServer(new TestServer())
                 .UseStartup("Microsoft.AspNetCore.Hosting.Tests")
-                .Build();
+                .Build())
-
+            {
                 var appBase = PlatformServices.Default.Application.ApplicationBasePath;
                 Assert.Equal(appBase, host.Services.GetService<IHostingEnvironment>().ContentRootPath);
             }
+        }
 
         [Fact]
         public void DefaultApplicationNameToStartupAssemblyName()
         {
             var builder = new ConfigurationBuilder();
-            var host = new WebHostBuilder()
+            using (var host = new WebHostBuilder()
                 .UseServer(new TestServer())
                 .UseStartup("Microsoft.AspNetCore.Hosting.Tests")
-                .Build();
+                .Build())
-
+            {
                 var hostingEnv = host.Services.GetService<IHostingEnvironment>();
                 Assert.Equal("Microsoft.AspNetCore.Hosting.Tests", hostingEnv.ApplicationName);
             }
+        }
 
         [Fact]
         public void DefaultApplicationNameToStartupType()
         {
             var builder = new ConfigurationBuilder();
-            var host = new WebHostBuilder()
+            using (var host = new WebHostBuilder()
                 .UseServer(new TestServer())
                 .UseStartup<StartupNoServices>()
                 .UseStartup("Microsoft.AspNetCore.Hosting.Tests.NonExistent")
-                .Build();
+                .Build())
-
+            {
                 var hostingEnv = host.Services.GetService<IHostingEnvironment>();
                 Assert.Equal("Microsoft.AspNetCore.Hosting.Tests.NonExistent", hostingEnv.ApplicationName);
             }
+        }
 
         [Fact]
         public void DefaultApplicationNameAndBasePathToStartupMethods()
         {
             var builder = new ConfigurationBuilder();
-            var host = new WebHostBuilder()
+            using (var host = new WebHostBuilder()
                 .UseServer(new TestServer())
                 .Configure(app => { })
                 .UseStartup("Microsoft.AspNetCore.Hosting.Tests.NonExistent")
-                .Build();
+                .Build())
-
+            {
                 var hostingEnv = host.Services.GetService<IHostingEnvironment>();
                 Assert.Equal("Microsoft.AspNetCore.Hosting.Tests.NonExistent", hostingEnv.ApplicationName);
             }
+        }
 
         [Fact]
         public void Configure_SupportsNonStaticMethodDelegate()
         {
-            var host = new WebHostBuilder()
+            using (var host = new WebHostBuilder()
                 .UseServer(new TestServer())
                 .Configure(app => { })
-                .Build();
+                .Build())
-
+            {
                 var hostingEnv = host.Services.GetService<IHostingEnvironment>();
                 Assert.Equal("Microsoft.AspNetCore.Hosting.Tests", hostingEnv.ApplicationName);
             }
+        }
 
         [Fact]
         public void Configure_SupportsStaticMethodDelegate()
         {
-            var host = new WebHostBuilder()
+            using (var host = new WebHostBuilder()
                 .UseServer(new TestServer())
                 .Configure(StaticConfigureMethod)
-                .Build();
+                .Build())
-
+            {
                 var hostingEnv = host.Services.GetService<IHostingEnvironment>();
                 Assert.Equal("Microsoft.AspNetCore.Hosting.Tests", hostingEnv.ApplicationName);
             }
+        }
 
         [Fact]
         public void Build_DoesNotAllowBuildingMuiltipleTimes()
         {
             var builder = CreateWebHostBuilder();
             var server = new TestServer();
-            builder.UseServer(server)
+            using (builder.UseServer(server)
                 .UseStartup<StartupNoServices>()
-                .Build();
+                .Build())
-
+            {
                 var ex = Assert.Throws<InvalidOperationException>(() => builder.Build());
-
                 Assert.Equal("WebHostBuilder allows creation only of a single instance of WebHost", ex.Message);
             }
+        }
 
         [Fact]
         public void Build_PassesSameAutoCreatedILoggerFactoryEverywhere()
         {
             var builder = CreateWebHostBuilder();
             var server = new TestServer();
-            var host = builder.UseServer(server)
+            using (var host = builder.UseServer(server)
                 .UseStartup<StartupWithILoggerFactory>()
-                .Build();
+                .Build())
-
+            {
                 var startup = host.Services.GetService<StartupWithILoggerFactory>();
-
                 Assert.Equal(startup.ConfigureLoggerFactory, startup.ConstructorLoggerFactory);
             }
+        }
 
         [Fact]
         public void Build_PassesSamePassedILoggerFactoryEverywhere()
@@ -708,16 +759,16 @@ namespace Microsoft.AspNetCore.Hosting
             var factory = new LoggerFactory();
             var builder = CreateWebHostBuilder();
             var server = new TestServer();
-            var host = builder.UseServer(server)
+            using (var host = builder.UseServer(server)
                 .UseLoggerFactory(factory)
                 .UseStartup<StartupWithILoggerFactory>()
-                .Build();
+                .Build())
-
+            {
                 var startup = host.Services.GetService<StartupWithILoggerFactory>();
-
                 Assert.Equal(factory, startup.ConfigureLoggerFactory);
                 Assert.Equal(factory, startup.ConstructorLoggerFactory);
             }
+        }
 
         [Fact]
         public void Build_PassedILoggerFactoryNotDisposed()
@@ -726,12 +777,10 @@ namespace Microsoft.AspNetCore.Hosting
             var builder = CreateWebHostBuilder();
             var server = new TestServer();
 
-            var host = builder.UseServer(server)
+            using (var host = builder.UseServer(server)
                 .UseLoggerFactory(factory)
                 .UseStartup<StartupWithILoggerFactory>()
-                .Build();
+                .Build()) { }
-
-            host.Dispose();
 
             Assert.Equal(false, factory.Disposed);
         }
@@ -743,14 +792,15 @@ namespace Microsoft.AspNetCore.Hosting
             var builder = CreateWebHostBuilder();
             var server = new TestServer();
 
-            var host = builder.UseServer(server)
+            using (var host = builder.UseServer(server)
                 .ConfigureServices(collection => collection.AddSingleton<ILoggerFactory>(factory))
                 .UseStartup<StartupWithILoggerFactory>()
-                .Build();
+                .Build())
-
+            {
                 var factoryFromHost = host.Services.GetService<ILoggerFactory>();
                 Assert.Equal(factory, factoryFromHost);
             }
+        }
 
         [Fact]
         public void Build_RunsHostingStartupAssembliesIfSpecified()
@@ -761,10 +811,11 @@ namespace Microsoft.AspNetCore.Hosting
                 .Configure(app => { })
                 .UseServer(new TestServer());
 
-            var host = (WebHost)builder.Build();
+            using (var host = builder.Build())
-
+            {
                 Assert.Equal("1", builder.GetSetting("testhostingstartup"));
             }
+        }
 
         [Fact]
         public void Build_RunsHostingStartupAssembliesBeforeApplication()
@@ -782,11 +833,12 @@ namespace Microsoft.AspNetCore.Hosting
                 })
                 .UseServer(new TestServer());
 
-            var host = (WebHost)builder.Build();
+            using (builder.Build())
-
+            {
                 Assert.NotNull(startup.ServiceADescriptor);
                 Assert.NotNull(startup.ServiceA);
             }
+        }
 
         [Fact]
         public void Build_ConfigureLoggingInHostingStartupWorks()
@@ -802,10 +854,12 @@ namespace Microsoft.AspNetCore.Hosting
                 })
                 .UseServer(new TestServer());
 
-            var host = (WebHost)builder.Build();
+            using (var host = (WebHost)builder.Build())
+            {
                 var sink = host.Services.GetRequiredService<ITestSink>();
                 Assert.True(sink.Writes.Any(w => w.State.ToString() == "From startup"));
             }
+        }
 
         [Fact]
         public void Build_DoesNotRunHostingStartupAssembliesDoNotRunIfNotSpecified()
@@ -814,10 +868,11 @@ namespace Microsoft.AspNetCore.Hosting
                 .Configure(app => { })
                 .UseServer(new TestServer());
 
-            var host = (WebHost)builder.Build();
+            using (builder.Build())
-
+            {
                 Assert.Null(builder.GetSetting("testhostingstartup"));
             }
+        }
 
         [Fact]
         public void Build_ThrowsIfUnloadableAssemblyNameInHostingStartupAssemblies()
@@ -828,7 +883,7 @@ namespace Microsoft.AspNetCore.Hosting
                 .Configure(app => { })
                 .UseServer(new TestServer());
 
-            var ex = Assert.Throws<AggregateException>(() => (WebHost)builder.Build());
+            var ex = Assert.Throws<AggregateException>(() => builder.Build());
             Assert.IsType<InvalidOperationException>(ex.InnerExceptions[0]);
             Assert.IsType<FileNotFoundException>(ex.InnerExceptions[0].InnerException);
         }
@@ -867,8 +922,7 @@ namespace Microsoft.AspNetCore.Hosting
             Assert.Throws<ArgumentException>(() => new HostingStartupAttribute(typeof(WebHostTests)));
         }
 
-        private static void StaticConfigureMethod(IApplicationBuilder app)
+        private static void StaticConfigureMethod(IApplicationBuilder app) { }
-        { }
 
         private IWebHostBuilder CreateWebHostBuilder()
         {
@@ -898,10 +952,7 @@ namespace Microsoft.AspNetCore.Hosting
             IFeatureCollection IServer.Features { get; }
             public RequestDelegate RequestDelegate { get; private set; }
 
-            public void Dispose()
+            public void Dispose() { }
-            {
-
-            }
 
             public Task StartAsync<TContext>(IHttpApplication<TContext> application, CancellationToken cancellationToken)
             {
@@ -923,10 +974,7 @@ namespace Microsoft.AspNetCore.Hosting
                 return Task.CompletedTask;
             }
 
-            public Task StopAsync(CancellationToken cancellationToken)
+            public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
-            {
-                return Task.CompletedTask;
-            }
         }
 
         internal class StartupVerifyServiceA : IStartup
@@ -964,39 +1012,21 @@ namespace Microsoft.AspNetCore.Hosting
         {
             public TestSink Sink { get; set; } = new TestSink();
 
-            public ILogger CreateLogger(string categoryName)
+            public ILogger CreateLogger(string categoryName) => new TestLogger(categoryName, Sink, enabled: true);
-            {
-                return new TestLogger(categoryName, Sink, enabled: true);
-            }
 
-            public void Dispose()
+            public void Dispose() { }
-            {
-
-            }
         }
 
         private class ServiceC
         {
-            public ServiceC(ServiceD serviceD)
+            public ServiceC(ServiceD serviceD) { }
-            {
-
-            }
         }
 
-        internal class ServiceD
+        internal class ServiceD { }
-        {
 
-        }
+        internal class ServiceA { }
 
-        internal class ServiceA
+        internal class ServiceB { }
-        {
-
-        }
-
-        internal class ServiceB
-        {
-
-        }
 
         private class DisposableLoggerFactory : ILoggerFactory
         {
@@ -1007,14 +1037,9 @@ namespace Microsoft.AspNetCore.Hosting
 
             public bool Disposed { get; set; }
 
-            public ILogger CreateLogger(string categoryName)
+            public ILogger CreateLogger(string categoryName) => NullLogger.Instance;
-            {
-                return NullLogger.Instance;
-            }
 
-            public void AddProvider(ILoggerProvider provider)
+            public void AddProvider(ILoggerProvider provider) { }
-            {
-            }
         }
     }
 }