Enable nullable for dotnet test MTP implementation (#50731)

Author: Youssef1313

src/Cli/dotnet/Commands/Test/CliConstants.cs

@@ -1,8 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#nullable disable
-
 namespace Microsoft.DotNet.Cli.Commands.Test;
 
 internal static class CliConstants

src/Cli/dotnet/Commands/Test/MTP/ExitCode.cs

@@ -1,8 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#nullable disable
-
 namespace Microsoft.DotNet.Cli.Commands.Test;
 
 // IMPORTANT: The exit codes must match MTP:

src/Cli/dotnet/Commands/Test/MTP/IPC/INamedPipeBase.cs

@@ -1,8 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#nullable disable
-
 namespace Microsoft.DotNet.Cli.Commands.Test.IPC;
 
 internal interface INamedPipeBase

src/Cli/dotnet/Commands/Test/MTP/IPC/INamedPipeSerializer.cs

@@ -1,8 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#nullable disable
-
 namespace Microsoft.DotNet.Cli.Commands.Test.IPC;
 
 internal interface INamedPipeSerializer

src/Cli/dotnet/Commands/Test/MTP/IPC/IRequest.cs

@@ -1,8 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#nullable disable
-
 namespace Microsoft.DotNet.Cli.Commands.Test.IPC;
 
 internal interface IRequest

src/Cli/dotnet/Commands/Test/MTP/IPC/IResponse.cs

@@ -1,8 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#nullable disable
-
 namespace Microsoft.DotNet.Cli.Commands.Test.IPC;
 
 internal interface IResponse

src/Cli/dotnet/Commands/Test/MTP/IPC/Models/UnknownMessage.cs

@@ -1,8 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#nullable disable
-
 namespace Microsoft.DotNet.Cli.Commands.Test.IPC.Models;
 
 internal sealed record class UnknownMessage(int SerializerId) : IRequest;

src/Cli/dotnet/Commands/Test/MTP/IPC/Models/VoidResponse.cs

@@ -1,8 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#nullable disable
-
 namespace Microsoft.DotNet.Cli.Commands.Test.IPC.Models;
 
 internal sealed class VoidResponse : IResponse

src/Cli/dotnet/Commands/Test/MTP/IPC/NamedPipeBase.cs

@@ -1,8 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#nullable disable
-
 using System.Globalization;
 using Microsoft.DotNet.Cli.Commands.Test.IPC.Serializers;
 
@@ -21,7 +19,7 @@ public void RegisterSerializer(INamedPipeSerializer namedPipeSerializer, Type ty
 
     protected INamedPipeSerializer GetSerializer(int id, bool skipUnknownMessages = false)
     {
-        if (_idSerializer.TryGetValue(id, out INamedPipeSerializer serializer))
+        if (_idSerializer.TryGetValue(id, out INamedPipeSerializer? serializer))
         {
             return serializer;
         }
@@ -38,7 +36,7 @@ protected INamedPipeSerializer GetSerializer(int id, bool skipUnknownMessages =
 
 
     protected INamedPipeSerializer GetSerializer(Type type)
-        => _typeSerializer.TryGetValue(type, out INamedPipeSerializer serializer)
+        => _typeSerializer.TryGetValue(type, out INamedPipeSerializer? serializer)
             ? serializer
             : throw new ArgumentException(string.Format(
                 CultureInfo.InvariantCulture,

src/Cli/dotnet/Commands/Test/MTP/IPC/NamedPipeServer.cs

@@ -1,10 +1,9 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#nullable disable
-
 using System.Buffers;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.IO.Pipes;
 
@@ -22,7 +21,7 @@ internal sealed class NamedPipeServer : NamedPipeBase
     private readonly byte[] _readBuffer = new byte[250000];
     private readonly byte[] _sizeOfIntArray = new byte[sizeof(int)];
     private readonly bool _skipUnknownMessages;
-    private Task _loopTask;
+    private Task? _loopTask;
     private bool _disposed;
 
     public NamedPipeServer(
@@ -238,7 +237,7 @@ public void Dispose()
                 // This is unexpected and we throw an exception.
 
                 // To close gracefully we need to ensure that the client closed the stream line 103.
-                if (!_loopTask.Wait(TimeSpan.FromSeconds(90)))
+                if (!_loopTask!.Wait(TimeSpan.FromSeconds(90)))
                 {
                     throw new InvalidOperationException(CliCommandStrings.InternalLoopAsyncDidNotExitSuccessfullyErrorMessage);
                 }