Enable nullables on common

src/Microsoft.TestPlatform.Client/TestPlatform.cs

@@ -274,7 +274,7 @@ private static void AddExtensionAssembliesFromExtensionDirectory()
         // Otherwise we will always get a "No suitable test runtime provider found for this run." error.
         // I (@haplois) will modify this behavior later on, but we also need to consider legacy adapters
         // and make sure they still work after modification.
-        string runSettings = RunSettingsManager.Instance.ActiveRunSettings.SettingsXml;
+        string? runSettings = RunSettingsManager.Instance.ActiveRunSettings.SettingsXml;
         RunConfiguration runConfiguration = XmlRunSettingsUtilities.GetRunConfigurationNode(runSettings);
         TestAdapterLoadingStrategy strategy = runConfiguration.TestAdapterLoadingStrategy;
 

src/Microsoft.TestPlatform.Common/Constants.cs

@@ -1,8 +1,6 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
-#nullable disable
-
 namespace Microsoft.VisualStudio.TestPlatform.Common;
 
 /// <summary>

src/Microsoft.TestPlatform.Common/DataCollection/AfterTestRunEndResult.cs

@@ -7,8 +7,6 @@
 
 using Microsoft.VisualStudio.TestPlatform.ObjectModel;
 
-#nullable disable
-
 namespace Microsoft.VisualStudio.TestPlatform.Common.DataCollection;
 
 /// <summary>
@@ -21,7 +19,11 @@ public class AfterTestRunEndResult
     // We want to fallback to the non-public default constructor https://www.newtonsoft.com/json/help/html/T_Newtonsoft_Json_ConstructorHandling.htm during deserialization
     private AfterTestRunEndResult()
     {
-
+        // Forcing nulls to the differnet properties as this is only serialization ctor but
+        // we can guarantee non-null for the other ctors.
+        AttachmentSets = null!;
+        InvokedDataCollectors = null!;
+        Metrics = null!;
     }
 
     /// <summary>
@@ -50,7 +52,7 @@ public AfterTestRunEndResult(Collection<AttachmentSet> attachmentSets, IDictiona
     /// The metrics.
     /// </param>
     public AfterTestRunEndResult(Collection<AttachmentSet> attachmentSets,
-        Collection<InvokedDataCollector> invokedDataCollectors,
+        Collection<InvokedDataCollector>? invokedDataCollectors,
         IDictionary<string, object> metrics)
     {
         AttachmentSets = attachmentSets;
@@ -62,7 +64,7 @@ public AfterTestRunEndResult(Collection<AttachmentSet> attachmentSets,
     public Collection<AttachmentSet> AttachmentSets { get; private set; }
 
     [DataMember]
-    public Collection<InvokedDataCollector> InvokedDataCollectors { get; private set; }
+    public Collection<InvokedDataCollector>? InvokedDataCollectors { get; private set; }
 
     [DataMember]
     public IDictionary<string, object> Metrics { get; private set; }

src/Microsoft.TestPlatform.Common/DataCollection/BeforeTestRunStartResult.cs

@@ -4,8 +4,6 @@
 using System.Collections.Generic;
 using System.Runtime.Serialization;
 
-#nullable disable
-
 namespace Microsoft.VisualStudio.TestPlatform.Common.DataCollection;
 
 /// <summary>

src/Microsoft.TestPlatform.Common/DataCollection/DataCollectionAttachmentManager.cs

@@ -18,8 +18,6 @@
 using Microsoft.VisualStudio.TestPlatform.Utilities;
 using Microsoft.VisualStudio.TestPlatform.Utilities.Helpers.Interfaces;
 
-#nullable disable
-
 namespace Microsoft.VisualStudio.TestPlatform.Common.DataCollector;
 
 /// <summary>
@@ -48,7 +46,7 @@ internal class DataCollectionAttachmentManager : IDataCollectionAttachmentManage
     /// <summary>
     /// Logger for data collection messages
     /// </summary>
-    private IMessageSink _messageSink;
+    private IMessageSink? _messageSink;
 
     /// <summary>
     /// Attachment transfer tasks associated with a given datacollection context.
@@ -88,7 +86,7 @@ protected DataCollectionAttachmentManager(IFileHelper fileHelper)
     /// <summary>
     /// Gets the session output directory.
     /// </summary>
-    internal string SessionOutputDirectory { get; private set; }
+    internal string? SessionOutputDirectory { get; private set; }
 
     /// <summary>
     /// Gets the attachment sets for the given datacollection context.
@@ -162,7 +160,7 @@ public List<AttachmentSet> GetAttachments(DataCollectionContext dataCollectionCo
     }
 
     /// <inheritdoc/>
-    public void AddAttachment(FileTransferInformation fileTransferInfo, AsyncCompletedEventHandler sendFileCompletedCallback, Uri uri, string friendlyName)
+    public void AddAttachment(FileTransferInformation fileTransferInfo, AsyncCompletedEventHandler? sendFileCompletedCallback, Uri uri, string friendlyName)
     {
         ValidateArg.NotNull(fileTransferInfo, nameof(fileTransferInfo));
 
@@ -217,7 +215,7 @@ private static void Validate(FileTransferInformation fileTransferInfo, string lo
 
         if (!Directory.Exists(directoryName))
         {
-            Directory.CreateDirectory(directoryName);
+            Directory.CreateDirectory(directoryName!);
         }
         else if (File.Exists(localFilePath))
         {
@@ -240,7 +238,7 @@ private static void Validate(FileTransferInformation fileTransferInfo, string lo
     /// <param name="friendlyName">
     /// The friendly Name.
     /// </param>
-    private void AddNewFileTransfer(FileTransferInformation fileTransferInfo, AsyncCompletedEventHandler sendFileCompletedCallback, Uri uri, string friendlyName)
+    private void AddNewFileTransfer(FileTransferInformation fileTransferInfo, AsyncCompletedEventHandler? sendFileCompletedCallback, Uri uri, string friendlyName)
     {
         var context = fileTransferInfo.Context;
         TPDebug.Assert(
@@ -251,6 +249,7 @@ private void AddNewFileTransfer(FileTransferInformation fileTransferInfo, AsyncC
             ? fileTransferInfo.Context.TestExecId.Id.ToString()
             : string.Empty;
 
+        TPDebug.Assert(SessionOutputDirectory is not null, "SessionOutputDirectory is null.");
         var directoryPath = Path.Combine(
             SessionOutputDirectory,
             testCaseId);
@@ -354,7 +353,7 @@ private void LogError(string errorMessage, Uri collectorUri, string collectorFri
             args.TestCaseId = testCaseId;
         }
 
-        _messageSink.SendMessage(args);
+        _messageSink?.SendMessage(args);
     }
 
 }

src/Microsoft.TestPlatform.Common/DataCollection/DataCollectionEnvironmentVariable.cs

@@ -5,8 +5,6 @@
 
 using Microsoft.VisualStudio.TestPlatform.ObjectModel;
 
-#nullable disable
-
 namespace Microsoft.VisualStudio.TestPlatform.Common.DataCollector;
 
 /// <summary>
@@ -81,7 +79,7 @@ public string FirstDataCollectorThatRequested
     }
 
     /// <summary>
-    /// Adds the data collector to the list of data collectors that requested this variable. 
+    /// Adds the data collector to the list of data collectors that requested this variable.
     /// </summary>
     /// <param name="requestingDataCollectorFriendlyName">Friendly name of requesting data collector.</param>
     public void AddRequestingDataCollector(string requestingDataCollectorFriendlyName)