[Fixes #7541] Per-test class customization should not remove global (per-fixture) customization

src/Microsoft.AspNetCore.Mvc.Testing/WebApplicationFactory.cs

@@ -49,15 +49,9 @@ namespace Microsoft.AspNetCore.Mvc.Testing
         /// <typeparamref name="TEntryPoint" /> will be loaded as application assemblies.
         /// </para>
         /// </summary>
-        public WebApplicationFactory() : 
+        public WebApplicationFactory()
-            this(builder => { }, new WebApplicationFactoryClientOptions())
         {
-        }
+            _configuration = ConfigureWebHost;
-
-        private WebApplicationFactory(Action<IWebHostBuilder> configuration, WebApplicationFactoryClientOptions options)
-        {
-            _configuration = configuration;
-            ClientOptions = options;
         }
 
         /// <summary>
@@ -75,7 +69,7 @@ namespace Microsoft.AspNetCore.Mvc.Testing
         /// <summary>
         /// Gets the <see cref="WebApplicationFactoryClientOptions"/> used by <see cref="CreateClient()"/>.
         /// </summary>
-        public WebApplicationFactoryClientOptions ClientOptions { get; }
+        public WebApplicationFactoryClientOptions ClientOptions { get; private set; } = new WebApplicationFactoryClientOptions();
 
         /// <summary>
         /// Creates a new <see cref="WebApplicationFactory{TEntryPoint}"/> with a <see cref="IWebHostBuilder"/>
@@ -87,12 +81,16 @@ namespace Microsoft.AspNetCore.Mvc.Testing
         /// <returns>A new <see cref="WebApplicationFactory{TEntryPoint}"/>.</returns>
         public WebApplicationFactory<TEntryPoint> WithWebHostBuilder(Action<IWebHostBuilder> configuration)
         {
-            var factory = new WebApplicationFactory<TEntryPoint>(builder => 
+            var factory = new DelegatedWebApplicationFactory(
-            {
+                ClientOptions,
-                _configuration(builder);
+                CreateServer,
-                configuration(builder);
+                CreateWebHostBuilder,
-            },
+                GetTestAssemblies,
-            new WebApplicationFactoryClientOptions(ClientOptions));
+                builder =>
+                {
+                    _configuration(builder);
+                    configuration(builder);
+                });
 
             _derivedFactories.Add(factory);
 
@@ -111,7 +109,6 @@ namespace Microsoft.AspNetCore.Mvc.Testing
 
             var builder = CreateWebHostBuilder();
             SetContentRoot(builder);
-            ConfigureWebHost(builder);
             _configuration(builder);
             _server = CreateServer(builder);
         }
@@ -341,5 +338,34 @@ namespace Microsoft.AspNetCore.Mvc.Testing
 
             _server?.Dispose();
         }
+
+        private class DelegatedWebApplicationFactory : WebApplicationFactory<TEntryPoint>
+        {
+            private readonly Func<IWebHostBuilder, TestServer> _createServer;
+            private readonly Func<IWebHostBuilder> _createWebHostBuilder;
+            private readonly Func<IEnumerable<Assembly>> _getTestAssemblies;
+
+            public DelegatedWebApplicationFactory(
+                WebApplicationFactoryClientOptions options,
+                Func<IWebHostBuilder, TestServer> createServer,
+                Func<IWebHostBuilder> createWebHostBuilder,
+                Func<IEnumerable<Assembly>> getTestAssemblies,
+                Action<IWebHostBuilder> configureWebHost)
+            {
+                ClientOptions = new WebApplicationFactoryClientOptions(options);
+                _createServer = createServer;
+                _createWebHostBuilder = createWebHostBuilder;
+                _getTestAssemblies = getTestAssemblies;
+                _configuration = configureWebHost;
+            }
+
+            protected override TestServer CreateServer(IWebHostBuilder builder) => _createServer(builder);
+
+            protected override IWebHostBuilder CreateWebHostBuilder() => _createWebHostBuilder();
+
+            protected override IEnumerable<Assembly> GetTestAssemblies() => _getTestAssemblies();
+
+            protected override void ConfigureWebHost(IWebHostBuilder builder) => _configuration(builder);
+        }
     }
 }

test/Microsoft.AspNetCore.Mvc.FunctionalTests/TestingInfrastructureInheritanceTests.cs

@@ -0,0 +1,65 @@
+// Copyright (c) .NET  Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.AspNetCore.TestHost;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.FunctionalTests
+{
+    public class TestingInfrastructureInheritanceTests
+    {
+        [Fact]
+        public void TestingInfrastructure_WithWebHostBuilderRespectsCustomizations()
+        {
+            // Act
+            var factory = new CustomizedFactory<BasicWebSite.Startup>();
+            var customized = factory
+                .WithWebHostBuilder(builder => factory.ConfigureWebHostCalled.Add("Customization"))
+                .WithWebHostBuilder(builder => factory.ConfigureWebHostCalled.Add("FurtherCustomization"));
+            var client = customized.CreateClient();
+
+            // Assert
+            Assert.Equal(new[] { "ConfigureWebHost", "Customization", "FurtherCustomization" }, factory.ConfigureWebHostCalled.ToArray());
+            Assert.True(factory.CreateServerCalled);
+            Assert.True(factory.CreateWebHostBuilderCalled);
+            Assert.True(factory.GetTestAssembliesCalled);
+        }
+
+        private class CustomizedFactory<TEntryPoint> : WebApplicationFactory<TEntryPoint> where TEntryPoint : class
+        {
+            public bool GetTestAssembliesCalled { get; private set; }
+            public bool CreateWebHostBuilderCalled { get; private set; }
+            public bool CreateServerCalled { get; private set; }
+            public IList<string> ConfigureWebHostCalled { get; private set; } = new List<string>();
+
+            protected override void ConfigureWebHost(IWebHostBuilder builder)
+            {
+                ConfigureWebHostCalled.Add("ConfigureWebHost");
+                base.ConfigureWebHost(builder);
+            }
+
+            protected override TestServer CreateServer(IWebHostBuilder builder)
+            {
+                CreateServerCalled = true;
+                return base.CreateServer(builder);
+            }
+
+            protected override IWebHostBuilder CreateWebHostBuilder()
+            {
+                CreateWebHostBuilderCalled = true;
+                return base.CreateWebHostBuilder();
+            }
+
+            protected override IEnumerable<Assembly> GetTestAssemblies()
+            {
+                GetTestAssembliesCalled = true;
+                return base.GetTestAssemblies();
+            }
+        }
+    }
+}