If using extension of TestMethodAttribute then please contact vendor (ThreadSafeStringWriter)

Description

Parallel tests are failing sporadically if they are writing to console output.

Steps to reproduce

• Create default project dotnet new mstest
• Add many classes with tests
• Put Console.WriteLine("abc") in tests body
• Allow tests to be executed in parallel [assembly: Parallelize(Scope = ExecutionScope.ClassLevel)]
• Update mstest packages to version 2.2.9

Execute all tests via dotnet test many times and sometimes different error messages appear.

Exception thrown while executing test. If using extension of TestMethodAttribute then please contact vendor. Error message: An item with the same key has already been added. Key: out, Stack trace:    at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
   at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value)
   at Microsoft.VisualStudio.TestPlatform.MSTestAdapter.PlatformServices.ThreadSafeStringWriter.GetOrAddStringBuilder()
   at Microsoft.VisualStudio.TestPlatform.MSTestAdapter.PlatformServices.ThreadSafeStringWriter..ctor(IFormatProvider formatProvider, String outputType)
   at Microsoft.VisualStudio.TestPlatform.MSTest.TestAdapter.Execution.LogMessageListener..ctor(Boolean captureDebugTraces)
   at Microsoft.VisualStudio.TestPlatform.MSTest.TestAdapter.Execution.TestMethodInfo.Invoke(Object[] arguments)
   at Microsoft.VisualStudio.TestTools.UnitTesting.TestMethodAttribute.Execute(ITestMethod testMethod)
   at Microsoft.VisualStudio.TestPlatform.MSTest.TestAdapter.Execution.TestMethodRunner.ExecuteTest(TestMethodInfo testMethodInfo)

or

An exception occurred while invoking executor 'executor://mstestadapter/v2': One or more errors occurred. (An item with the same key has already been added. Key: context)
Stack trace:
   at System.Threading.Tasks.Task.WaitAllCore(Task[] tasks, Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at Microsoft.VisualStudio.TestPlatform.MSTest.TestAdapter.Execution.TestExecutionManager.ExecuteTestsInSource(IEnumerable`1 tests, IRunContext runContext, IFrameworkHandle frameworkHandle, String source, Boolean isDeploymentDone)
   at Microsoft.VisualStudio.TestPlatform.MSTest.TestAdapter.Execution.TestExecutionManager.ExecuteTests(IEnumerable`1 tests, IRunContext runContext, IFrameworkHandle frameworkHandle, Boolean isDeploymentDone)
   at Microsoft.VisualStudio.TestPlatform.MSTest.TestAdapter.Execution.TestExecutionManager.RunTests(IEnumerable`1 sources, IRunContext runContext, IFrameworkHandle frameworkHandle, TestRunCancellationToken cancellationToken)
   at Microsoft.VisualStudio.TestPlatform.MSTest.TestAdapter.MSTestExecutor.RunTests(IEnumerable`1 sources, IRunContext runContext, IFrameworkHandle frameworkHandle)
   at Microsoft.VisualStudio.TestPlatform.CrossPlatEngine.Execution.RunTestsWithSources.InvokeExecutor(LazyExtension`2 executor, Tuple`2 executorUriExtensionTuple, RunContext runContext, IFrameworkHandle frameworkHandle)
   at Microsoft.VisualStudio.TestPlatform.CrossPlatEngine.Execution.BaseRunTests.RunTestInternalWithExecutors(IEnumerable`1 executorUriExtensionMap, Int64 totalTests)

Inner exception: An item with the same key has already been added. Key: context

Stack trace:
   at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
   at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value)
   at Microsoft.VisualStudio.TestPlatform.MSTestAdapter.PlatformServices.ThreadSafeStringWriter.GetOrAddStringBuilder()
   at Microsoft.VisualStudio.TestPlatform.MSTestAdapter.PlatformServices.ThreadSafeStringWriter..ctor(IFormatProvider formatProvider, String outputType)
   at Microsoft.VisualStudio.TestPlatform.MSTest.TestAdapter.Execution.UnitTestRunner.RunSingleTest(TestMethod testMethod, IDictionary`2 testContextProperties)
   at Microsoft.VisualStudio.TestPlatform.MSTest.TestAdapter.Execution.TestExecutionManager.ExecuteTestsWithTestRunner(IEnumerable`1 tests, IRunContext runContext, ITestExecutionRecorder testExecutionRecorder, String source, IDictionary`2 sourceLevelParameters, UnitTestRunner testRunner)
   at Microsoft.VisualStudio.TestPlatform.MSTest.TestAdapter.Execution.TestExecutionManager.<>c__DisplayClass17_1.<ExecuteTestsInSource>b__6()
   at System.Threading.Tasks.Task.InnerInvoke()
   at System.Threading.Tasks.Task.<>c.<.cctor>b__272_0(Object obj)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)

or

 An item with the same key has already been added. Key: err
  Stack Trace:
     at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
   at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value)
   at Microsoft.VisualStudio.TestPlatform.MSTestAdapter.PlatformServices.ThreadSafeStringWriter.GetOrAddStringBuilder()
   at Microsoft.VisualStudio.TestPlatform.MSTestAdapter.PlatformServices.ThreadSafeStringWriter..ctor(IFormatProvider formatProvider, String outputType)

or

 Operations that change non-concurrent collections must have exclusive access. A concurrent update was performed on this collection and corrupted its state. The collection's state is no longer correct.
  Stack Trace:
     at System.Collections.Generic.Dictionary`2.Remove(TKey key)
   at Microsoft.VisualStudio.TestPlatform.MSTestAdapter.PlatformServices.ThreadSafeStringWriter.Dispose(Boolean disposing)
   at System.IO.TextWriter.Dispose()

Everything is related to MSTestAdapter.PlatformServices.ThreadSafeStringWriter.

Versions

<PackageReference Include="MSTest.TestAdapter" Version="2.2.9" />
<PackageReference Include="MSTest.TestFramework" Version="2.2.9" />

Also reproducible in 2.2.8.

[jcoliz]

@Haplois Confirmed here as well. Both on my actual use case and on the synthetic repro.

[nvborisenko]

Verified on 2.2.10-preview-20220414-01, the issue went away.