Add a workaround for xUnit bug

We're currently experiencing a bug where conditional skips aren't working in VS.
This is caused by https://github.com/xunit/xunit/issues/1782
\n\nCommit migrated from cbe90b8492

src/Testing/src/xunit/ConditionalTheoryDiscoverer.cs

@@ -1,6 +1,7 @@
 // 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;
 using System.Collections.Generic;
 using Xunit.Abstractions;
 using Xunit.Sdk;
@@ -63,5 +64,24 @@ namespace Microsoft.AspNetCore.Testing
                 base.CreateTestCasesForSkippedDataRow(discoveryOptions, testMethod, theoryAttribute, dataRow, skipReason)
                 : base.CreateTestCasesForDataRow(discoveryOptions, testMethod, theoryAttribute, dataRow);
         }
+
+        protected override IEnumerable<IXunitTestCase> CreateTestCasesForSkippedDataRow(
+            ITestFrameworkDiscoveryOptions discoveryOptions,
+            ITestMethod testMethod,
+            IAttributeInfo theoryAttribute,
+            object[] dataRow,
+            string skipReason)
+        {
+            return new[]
+            {
+                new WORKAROUND_SkippedDataRowTestCase(DiagnosticMessageSink, discoveryOptions.MethodDisplayOrDefault(), discoveryOptions.MethodDisplayOptionsOrDefault(), testMethod, skipReason, dataRow),
+            };
+        }
+
+        [Obsolete]
+        protected override IXunitTestCase CreateTestCaseForSkippedDataRow(ITestFrameworkDiscoveryOptions discoveryOptions, ITestMethod testMethod, IAttributeInfo theoryAttribute, object[] dataRow, string skipReason)
+        {
+            return new WORKAROUND_SkippedDataRowTestCase(DiagnosticMessageSink, discoveryOptions.MethodDisplayOrDefault(), discoveryOptions.MethodDisplayOptionsOrDefault(), testMethod, skipReason, dataRow);
+        }
     }
 }

src/Testing/src/xunit/SkippedTestCase.cs

@@ -2,6 +2,8 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Threading;
+using System.Threading.Tasks;
 using Xunit.Abstractions;
 using Xunit.Sdk;
 
@@ -33,8 +35,11 @@ namespace Microsoft.AspNetCore.Testing
 
         public override void Deserialize(IXunitSerializationInfo data)
         {
-            base.Deserialize(data);
             _skipReason = data.GetValue<string>(nameof(_skipReason));
+
+            // We need to call base after reading our value, because Deserialize will call
+            // into GetSkipReason.
+            base.Deserialize(data);
         }
 
         public override void Serialize(IXunitSerializationInfo data)

src/Testing/src/xunit/WORKAROUND_SkippedDataRowTestCase.cs

@@ -0,0 +1,80 @@
+using System;
+using System.ComponentModel;
+using Xunit.Abstractions;
+using Xunit.Sdk;
+
+namespace Microsoft.AspNetCore.Testing
+{
+    // This is a workaround for https://github.com/xunit/xunit/issues/1782 - as such, this code is a copy-paste
+    // from xUnit with the exception of fixing the bug.
+    //
+    // This will only work with [ConditionalTheory].
+    internal class WORKAROUND_SkippedDataRowTestCase : XunitTestCase
+    {
+        string skipReason;
+
+        /// <summary/>
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        [Obsolete("Called by the de-serializer; should only be called by deriving classes for de-serialization purposes")]
+        public WORKAROUND_SkippedDataRowTestCase() { }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="XunitSkippedDataRowTestCase"/> class.
+        /// </summary>
+        /// <param name="diagnosticMessageSink">The message sink used to send diagnostic messages</param>
+        /// <param name="defaultMethodDisplay">Default method display to use (when not customized).</param>
+        /// <param name="testMethod">The test method this test case belongs to.</param>
+        /// <param name="skipReason">The reason that this test case will be skipped</param>
+        /// <param name="testMethodArguments">The arguments for the test method.</param>
+        [Obsolete("Please call the constructor which takes TestMethodDisplayOptions")]
+        public WORKAROUND_SkippedDataRowTestCase(IMessageSink diagnosticMessageSink,
+                                           TestMethodDisplay defaultMethodDisplay,
+                                           ITestMethod testMethod,
+                                           string skipReason,
+                                           object[] testMethodArguments = null)
+            : this(diagnosticMessageSink, defaultMethodDisplay, TestMethodDisplayOptions.None, testMethod, skipReason, testMethodArguments) { }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="XunitSkippedDataRowTestCase"/> class.
+        /// </summary>
+        /// <param name="diagnosticMessageSink">The message sink used to send diagnostic messages</param>
+        /// <param name="defaultMethodDisplay">Default method display to use (when not customized).</param>
+        /// <param name="defaultMethodDisplayOptions">Default method display options to use (when not customized).</param>
+        /// <param name="testMethod">The test method this test case belongs to.</param>
+        /// <param name="skipReason">The reason that this test case will be skipped</param>
+        /// <param name="testMethodArguments">The arguments for the test method.</param>
+        public WORKAROUND_SkippedDataRowTestCase(IMessageSink diagnosticMessageSink,
+                                           TestMethodDisplay defaultMethodDisplay,
+                                           TestMethodDisplayOptions defaultMethodDisplayOptions,
+                                           ITestMethod testMethod,
+                                           string skipReason,
+                                           object[] testMethodArguments = null)
+            : base(diagnosticMessageSink, defaultMethodDisplay, defaultMethodDisplayOptions, testMethod, testMethodArguments)
+        {
+            this.skipReason = skipReason;
+        }
+
+        /// <inheritdoc/>
+        public override void Deserialize(IXunitSerializationInfo data)
+        {
+            // SkipReason has to be read before we call base.Deserialize, this is the workaround.
+            this.skipReason = data.GetValue<string>("SkipReason");
+
+            base.Deserialize(data);
+        }
+
+        /// <inheritdoc/>
+        protected override string GetSkipReason(IAttributeInfo factAttribute)
+        {
+            return skipReason;
+        }
+
+        /// <inheritdoc/>
+        public override void Serialize(IXunitSerializationInfo data)
+        {
+            base.Serialize(data);
+
+            data.AddValue("SkipReason", skipReason);
+        }
+    }
+}