Remove custom output device; use platform config for output

Removed CoverageSessionHandler and CoverletOutputDevice, eliminating custom output display and session messaging. Updated CoverletExtensionCollector to determine the coverage report output directory using the Microsoft Testing Platform configuration, and removed the OutputDirectory property from CoverletExtensionConfiguration. These changes streamline integration with the platform and ensure reports are written to the correct test result directory.

Author: Bertk

src/coverlet.MTP/CoverageSessionHandler.cs

@@ -9,6 +9,9 @@
 using Coverlet.Core.Reporters;
 using Coverlet.Core.Symbols;
 using Coverlet.MTP.CommandLine;
+using Microsoft.Testing.Platform.Configurations;
+using Microsoft.Testing.Platform.Logging;
+using Microsoft.Testing.Platform.CommandLine;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Testing.Platform.Extensions;
 using Microsoft.Testing.Platform.Extensions.TestHostControllers;
@@ -25,10 +28,10 @@ internal sealed class CoverletExtensionCollector : ITestHostProcessLifetimeHandl
   private readonly CoverletLoggerAdapter _logger;
   private readonly CoverletExtensionConfiguration _configuration;
   private IServiceProvider? _serviceProvider;
-  private readonly Microsoft.Testing.Platform.Configurations.IConfiguration? _platformConfiguration;
+  private readonly IConfiguration? _platformConfiguration;
   private Coverage? _coverage;
-  private readonly Microsoft.Testing.Platform.Logging.ILoggerFactory _loggerFactory;
-  private readonly Microsoft.Testing.Platform.CommandLine.ICommandLineOptions _commandLineOptions;
+  private readonly ILoggerFactory _loggerFactory;
+  private readonly ICommandLineOptions _commandLineOptions;
   private bool _coverageEnabled;
   private string? _testModulePath;
   private string? _coverageIdentifier;
@@ -55,7 +58,7 @@ public CoverletExtensionCollector(
   {
     _loggerFactory = loggerFactory ?? throw new ArgumentNullException(nameof(loggerFactory));
     _commandLineOptions = commandLineOptions ?? throw new ArgumentNullException(nameof(commandLineOptions));
-    _platformConfiguration = configuration;
+    _platformConfiguration = configuration ?? throw new ArgumentNullException(nameof(loggerFactory));
     _configuration = new CoverletExtensionConfiguration();
     _logger = new CoverletLoggerAdapter(_loggerFactory);
 
@@ -282,7 +285,7 @@ private void InitializeCoverage()
 
   private async Task GenerateReportsAsync(CoverageResult result, CancellationToken cancellation)
   {
-    string outputDirectory = _configuration.OutputDirectory ??
+    string outputDirectory = _platformConfiguration!.GetTestResultDirectory() ??
       Path.GetDirectoryName(_testModulePath) + Path.DirectorySeparatorChar;
 
     string directory = Path.GetDirectoryName(outputDirectory)!;

src/coverlet.MTP/CoverletExtensionCollector.cs

@@ -9,7 +9,6 @@ namespace coverlet.Extension.Collector
   internal class CoverletExtensionConfiguration
   {
     public string[] formats { get; set; } = ["json"];
-    public string? OutputDirectory { get; set; }
 
     // Coverage parameters
     public string[]? IncludeFilters { get; set; }