Introduce RetryAttribute for test methods

src/Adapter/MSTest.TestAdapter/Execution/TestExecutionManager.cs

@@ -39,7 +39,7 @@ public void SendMessage(TestMessageLevel testMessageLevel, string message)
     /// </summary>
     private readonly IDictionary<string, object> _sessionParameters;
     private readonly IEnvironment _environment;
-    private readonly Func<Action, Task> _taskFactory;
+    private readonly Func<Func<Task>, Task> _taskFactory;
 
     /// <summary>
     /// Specifies whether the test run is canceled or not.
@@ -51,15 +51,15 @@ public TestExecutionManager()
     {
     }
 
-    internal TestExecutionManager(IEnvironment environment, Func<Action, Task>? taskFactory = null)
+    internal TestExecutionManager(IEnvironment environment, Func<Func<Task>, Task>? taskFactory = null)
     {
         _testMethodFilter = new TestMethodFilter();
         _sessionParameters = new Dictionary<string, object>();
         _environment = environment;
         _taskFactory = taskFactory ?? DefaultFactoryAsync;
     }
 
-    private static Task DefaultFactoryAsync(Action action)
+    private static Task DefaultFactoryAsync(Func<Task> taskGetter)
     {
         if (MSTestSettings.RunConfigurationSettings.ExecutionApartmentState == ApartmentState.STA
             && RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
@@ -69,7 +69,9 @@ private static Task DefaultFactoryAsync(Action action)
             {
                 try
                 {
-                    action();
+                    // This is best we can do to execute in STA thread.
+                    Task task = taskGetter();
+                    task.GetAwaiter().GetResult();
                     tcs.SetResult(0);
                 }
                 catch (Exception ex)
@@ -84,7 +86,7 @@ private static Task DefaultFactoryAsync(Action action)
         }
         else
         {
-            return Task.Run(action);
+            return taskGetter();
         }
     }
 
@@ -121,7 +123,9 @@ public void RunTests(IEnumerable<TestCase> tests, IRunContext? runContext, IFram
         CacheSessionParameters(runContext, frameworkHandle);
 
         // Execute the tests
-        ExecuteTests(tests, runContext, frameworkHandle, isDeploymentDone);
+        // This is a public API, so we can't change it to be async.
+        // Consider not using this API internally, and introduce an async version, and mark this as obsolete.
+        ExecuteTestsAsync(tests, runContext, frameworkHandle, isDeploymentDone).GetAwaiter().GetResult();
 
         if (!_hasAnyTestFailed)
         {
@@ -159,7 +163,9 @@ public void RunTests(IEnumerable<string> sources, IRunContext? runContext, IFram
         CacheSessionParameters(runContext, frameworkHandle);
 
         // Run tests.
-        ExecuteTests(tests, runContext, frameworkHandle, isDeploymentDone);
+        // This is a public API, so we can't change it to be async.
+        // Consider not using this API internally, and introduce an async version, and mark this as obsolete.
+        ExecuteTestsAsync(tests, runContext, frameworkHandle, isDeploymentDone).GetAwaiter().GetResult();
 
         if (!_hasAnyTestFailed)
         {
@@ -174,7 +180,7 @@ public void RunTests(IEnumerable<string> sources, IRunContext? runContext, IFram
     /// <param name="runContext">The run context.</param>
     /// <param name="frameworkHandle">Handle to record test start/end/results.</param>
     /// <param name="isDeploymentDone">Indicates if deployment is done.</param>
-    internal virtual void ExecuteTests(IEnumerable<TestCase> tests, IRunContext? runContext, IFrameworkHandle frameworkHandle, bool isDeploymentDone)
+    internal virtual async Task ExecuteTestsAsync(IEnumerable<TestCase> tests, IRunContext? runContext, IFrameworkHandle frameworkHandle, bool isDeploymentDone)
     {
         var testsBySource = from test in tests
                             group test by test.Source into testGroup
@@ -183,7 +189,7 @@ group test by test.Source into testGroup
         foreach (var group in testsBySource)
         {
             _testRunCancellationToken?.ThrowIfCancellationRequested();
-            ExecuteTestsInSource(group.Tests, runContext, frameworkHandle, group.Source, isDeploymentDone);
+            await ExecuteTestsInSourceAsync(group.Tests, runContext, frameworkHandle, group.Source, isDeploymentDone);
         }
     }
 
@@ -257,7 +263,7 @@ private static bool MatchTestFilter(ITestCaseFilterExpression? filterExpression,
     /// <param name="frameworkHandle">Handle to record test start/end/results.</param>
     /// <param name="source">The test container for the tests.</param>
     /// <param name="isDeploymentDone">Indicates if deployment is done.</param>
-    private void ExecuteTestsInSource(IEnumerable<TestCase> tests, IRunContext? runContext, IFrameworkHandle frameworkHandle, string source, bool isDeploymentDone)
+    private async Task ExecuteTestsInSourceAsync(IEnumerable<TestCase> tests, IRunContext? runContext, IFrameworkHandle frameworkHandle, string source, bool isDeploymentDone)
     {
         DebugEx.Assert(!StringEx.IsNullOrEmpty(source), "Source cannot be empty");
 
@@ -363,7 +369,7 @@ private void ExecuteTestsInSource(IEnumerable<TestCase> tests, IRunContext? runC
                 {
                     _testRunCancellationToken?.ThrowIfCancellationRequested();
 
-                    tasks.Add(_taskFactory(() =>
+                    tasks.Add(_taskFactory(async () =>
                     {
                         try
                         {
@@ -373,7 +379,7 @@ private void ExecuteTestsInSource(IEnumerable<TestCase> tests, IRunContext? runC
 
                                 if (queue.TryDequeue(out IEnumerable<TestCase>? testSet))
                                 {
-                                    ExecuteTestsWithTestRunner(testSet, frameworkHandle, source, sourceLevelParameters, testRunner);
+                                    await ExecuteTestsWithTestRunnerAsync(testSet, frameworkHandle, source, sourceLevelParameters, testRunner);
                                 }
                             }
                         }
@@ -385,7 +391,7 @@ private void ExecuteTestsInSource(IEnumerable<TestCase> tests, IRunContext? runC
 
                 try
                 {
-                    Task.WaitAll(tasks.ToArray());
+                    await Task.WhenAll(tasks);
                 }
                 catch (Exception ex)
                 {
@@ -399,12 +405,12 @@ private void ExecuteTestsInSource(IEnumerable<TestCase> tests, IRunContext? runC
             // Queue the non parallel set
             if (nonParallelizableTestSet != null)
             {
-                ExecuteTestsWithTestRunner(nonParallelizableTestSet, frameworkHandle, source, sourceLevelParameters, testRunner);
+                await ExecuteTestsWithTestRunnerAsync(nonParallelizableTestSet, frameworkHandle, source, sourceLevelParameters, testRunner);
             }
         }
         else
         {
-            ExecuteTestsWithTestRunner(testsToRun, frameworkHandle, source, sourceLevelParameters, testRunner);
+            await ExecuteTestsWithTestRunnerAsync(testsToRun, frameworkHandle, source, sourceLevelParameters, testRunner);
         }
 
         if (PlatformServiceProvider.Instance.IsGracefulStopRequested)
@@ -415,7 +421,7 @@ private void ExecuteTestsInSource(IEnumerable<TestCase> tests, IRunContext? runC
         PlatformServiceProvider.Instance.AdapterTraceLogger.LogInfo("Executed tests belonging to source {0}", source);
     }
 
-    private void ExecuteTestsWithTestRunner(
+    private Task ExecuteTestsWithTestRunnerAsync(
         IEnumerable<TestCase> tests,
         ITestExecutionRecorder testExecutionRecorder,
         string source,
@@ -462,7 +468,10 @@ private void ExecuteTestsWithTestRunner(
 
             // testRunner could be in a different AppDomain. We cannot pass the testExecutionRecorder directly.
             // Instead, we pass a proxy (remoting object) that is marshallable by ref.
+#pragma warning disable VSTHRD103 // Call async methods when in an async method - We cannot do right now because we are crossing app domains.
+            // TODO: Use await testRunner.RunSingleTestAsync.
             UnitTestResult[] unitTestResult = testRunner.RunSingleTest(unitTestElement.TestMethod, testContextProperties, remotingMessageLogger);
+#pragma warning restore VSTHRD103 // Call async methods when in an async method
 
             PlatformServiceProvider.Instance.AdapterTraceLogger.LogInfo("Executed test {0}", unitTestElement.TestMethod.Name);
 
@@ -496,6 +505,8 @@ private void ExecuteTestsWithTestRunner(
                 SendTestResults(currentTest, [result], DateTimeOffset.Now, DateTimeOffset.Now, testExecutionRecorder);
             }
         }
+
+        return Task.CompletedTask;
     }
 
     /// <summary>

src/Adapter/MSTest.TestAdapter/Execution/TestMethodInfo.cs

@@ -46,6 +46,7 @@ internal TestMethodInfo(
         Parent = parent;
         TestMethodOptions = testMethodOptions;
         ExpectedException = ResolveExpectedException();
+        RetryAttribute = GetRetryAttribute();
     }
 
     /// <summary>
@@ -92,6 +93,8 @@ internal TestMethodInfo(
 
     internal ExpectedExceptionBaseAttribute? ExpectedException { get; set; /*set for testing only*/ }
 
+    internal RetryAttribute? RetryAttribute { get; }
+
     public Attribute[]? GetAllAttributes(bool inherit) => ReflectHelper.Instance.GetDerivedAttributes<Attribute>(TestMethod, inherit).ToArray();
 
     public TAttributeType[] GetAttributes<TAttributeType>(bool inherit)
@@ -260,6 +263,16 @@ public virtual TestResult Invoke(object?[]? arguments)
         return expectedExceptions.FirstOrDefault();
     }
 
+    /// <summary>
+    /// Gets the number of retries this test method should make in case of failure.
+    /// </summary>
+    /// <returns>
+    /// The number of retries, which is always greater than or equal to 1.
+    /// If RetryAttribute is not present, returns 1.
+    /// </returns>
+    private RetryAttribute? GetRetryAttribute()
+        => ReflectHelper.Instance.GetFirstDerivedAttributeOrDefault<RetryAttribute>(TestMethod, inherit: true);
+
     /// <summary>
     /// Execute test without timeout.
     /// </summary>

src/Adapter/MSTest.TestAdapter/Execution/TestMethodRunner.cs

@@ -173,6 +173,7 @@ internal List<TestResult> RunTestMethod()
         {
             if (_test.TestDataSourceIgnoreMessage is not null)
             {
+                _testContext.SetOutcome(UTF.UnitTestOutcome.Ignored);
                 return [new() { Outcome = UTF.UnitTestOutcome.Ignored, IgnoreReason = _test.TestDataSourceIgnoreMessage }];
             }
 

src/Adapter/MSTest.TestAdapter/Execution/UnitTestRunner.cs

@@ -6,6 +6,7 @@
 using Microsoft.VisualStudio.TestPlatform.MSTest.TestAdapter.Extensions;
 using Microsoft.VisualStudio.TestPlatform.MSTest.TestAdapter.Helpers;
 using Microsoft.VisualStudio.TestPlatform.MSTest.TestAdapter.ObjectModel;
+using Microsoft.VisualStudio.TestPlatform.MSTestAdapter;
 using Microsoft.VisualStudio.TestPlatform.MSTestAdapter.PlatformServices;
 using Microsoft.VisualStudio.TestPlatform.MSTestAdapter.PlatformServices.Interface;
 using Microsoft.VisualStudio.TestPlatform.ObjectModel.Logging;
@@ -122,13 +123,19 @@ internal FixtureTestResult GetFixtureTestResult(TestMethod testMethod, string fi
         static UnitTestOutcome GetOutcome(Exception? exception) => exception == null ? UnitTestOutcome.Passed : UnitTestOutcome.Failed;
     }
 
+    // Task cannot cross app domains.
+    // For now, TestExecutionManager will call this sync method which is hacky.
+    // If we removed AppDomains in v4, we should use the async method and remove this one.
+    internal UnitTestResult[] RunSingleTest(TestMethod testMethod, IDictionary<string, object?> testContextProperties, IMessageLogger messageLogger)
+        => RunSingleTestAsync(testMethod, testContextProperties, messageLogger).GetAwaiter().GetResult();
+
     /// <summary>
     /// Runs a single test.
     /// </summary>
     /// <param name="testMethod"> The test Method. </param>
     /// <param name="testContextProperties"> The test context properties. </param>
     /// <returns> The <see cref="UnitTestResult"/>. </returns>
-    internal UnitTestResult[] RunSingleTest(TestMethod testMethod, IDictionary<string, object?> testContextProperties, IMessageLogger messageLogger)
+    internal async Task<UnitTestResult[]> RunSingleTestAsync(TestMethod testMethod, IDictionary<string, object?> testContextProperties, IMessageLogger messageLogger)
     {
         Guard.NotNull(testMethod);
 
@@ -179,8 +186,23 @@ internal UnitTestResult[] RunSingleTest(TestMethod testMethod, IDictionary<strin
                     {
                         // Run the test method
                         testContextForTestExecution.SetOutcome(testContextForClassInit.Context.CurrentTestOutcome);
+                        RetryAttribute? retryAttribute = testMethodInfo.RetryAttribute;
                         var testMethodRunner = new TestMethodRunner(testMethodInfo, testMethod, testContextForTestExecution);
-                        result = testMethodRunner.Execute(classInitializeResult.StandardOut!, classInitializeResult.StandardError!, classInitializeResult.DebugTrace!, classInitializeResult.TestContextMessages!).ToUnitTestResults();
+                        List<TestResult> firstRunResult = testMethodRunner.Execute(classInitializeResult.StandardOut!, classInitializeResult.StandardError!, classInitializeResult.DebugTrace!, classInitializeResult.TestContextMessages!);
+                        result = firstRunResult.ToUnitTestResults();
+                        if (retryAttribute is not null && !RetryAttribute.IsAcceptableResultForRetry(firstRunResult))
+                        {
+                            RetryResult retryResult = await retryAttribute.ExecuteAsync(
+                                new RetryContext(
+                                    () => Task.FromResult(
+                                        testMethodRunner.Execute(
+                                            classInitializeResult.StandardOut!,
+                                            classInitializeResult.StandardError!,
+                                            classInitializeResult.DebugTrace!,
+                                            classInitializeResult.TestContextMessages!).ToArray())));
+
+                            result = retryResult.TryGetLast()?.ToUnitTestResults() ?? throw ApplicationStateGuard.Unreachable();
+                        }
                     }
                 }
             }

src/TestFramework/TestFramework/Attributes/TestMethod/DelayBackoffType.cs

@@ -0,0 +1,22 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+namespace Microsoft.VisualStudio.TestTools.UnitTesting;
+
+/// <summary>
+/// Specifies a backoff type for the delay between retries.
+/// </summary>
+public enum DelayBackoffType
+{
+    /// <summary>
+    /// Specifies a constant backoff type. Meaning the delay between retries is constant.
+    /// </summary>
+    Constant,
+
+    /// <summary>
+    /// Specifies an exponential backoff type.
+    /// The delay is calculated as the base delay * 2^(n-1) where n is the retry attempt.
+    /// For example, if the base delay is 1000ms, the delays will be 1000ms, 2000ms, 4000ms, 8000ms, etc.
+    /// </summary>
+    Exponential,
+}