Add affected test selection to dotnet test

src/Cli/Microsoft.DotNet.Cli.Definitions/CommandDefinitionStrings.resx

@@ -454,6 +454,24 @@ This is equivalent to deleting project.assets.json.</value>
   <data name="CmdListTestsDescription" xml:space="preserve">
     <value>List the discovered tests instead of running the tests. Optionally accepts a format: 'text' (default) for human-readable output or 'json' for machine-readable output.</value>
   </data>
+  <data name="CmdAffectedTestsFeatureDisabled" xml:space="preserve">
+    <value>Affected-test selection is experimental. Set the '{0}' environment variable to '1' to enable it.</value>
+  </data>
+  <data name="CmdAffectedTestsOptionsMutuallyExclusive" xml:space="preserve">
+    <value>The options '--collect-test-map' and '--affected-tests' cannot be used together.</value>
+  </data>
+  <data name="CmdCollectTestMapDescription" xml:space="preserve">
+    <value>Run tests and write the source-to-test map used by affected-test selection.</value>
+  </data>
+  <data name="CmdCollectTestMapCannotRunModulesInParallel" xml:space="preserve">
+    <value>The option '--collect-test-map' cannot be combined with '--max-parallel-test-modules'. Test maps are collected one module at a time.</value>
+  </data>
+  <data name="CmdCollectTestMapCannotRequireMinimumTests" xml:space="preserve">
+    <value>The option '--collect-test-map' cannot be combined with '--minimum-expected-tests'. Collection batches do not report test totals to the parent process.</value>
+  </data>
+  <data name="CmdAffectedTestsDescription" xml:space="preserve">
+    <value>Run only tests linked in the test map to sources changed in Git.</value>
+  </data>
   <data name="CmdLockedModeOptionDescription" xml:space="preserve">
     <value>Don't allow updating project lock file.</value>
   </data>

src/Cli/Microsoft.DotNet.Cli.Definitions/Commands/Test/TestCommandDefinition.MicrosoftTestingPlatform.cs

@@ -8,6 +8,7 @@
 using System.Text.RegularExpressions;
 using Microsoft.DotNet.Cli.CommandLine;
 using Microsoft.DotNet.Cli.Help;
+using Microsoft.DotNet.Cli.Utils;
 
 namespace Microsoft.DotNet.Cli.Commands.Test;
 
@@ -181,6 +182,18 @@ public sealed partial class MicrosoftTestingPlatform : TestCommandDefinition, IC
             Arity = ArgumentArity.Zero
         };
 
+        public const string EnableAffectedTestsEnvironmentVariable = "DOTNET_CLI_ENABLE_AFFECTED_TESTS";
+
+        public const string CollectTestMapOptionName = "--collect-test-map";
+
+        public readonly Option<bool> CollectTestMapOption;
+
+        public const string AffectedTestsOptionName = "--affected-tests";
+
+        public readonly Option<bool> AffectedTestsOption;
+
+        public bool AffectedTestsEnabled { get; }
+
         public readonly Option<string> ArtifactsPathOption = CommonOptions.CreateArtifactsPathOption();
 
         public const string BuildTargetName = "_MTPBuild";
@@ -195,6 +208,24 @@ public MicrosoftTestingPlatform()
             MinimumExpectedTestsOption.Validators.Add(ValidatePositiveInteger);
             MaximumFailedTestsOption.Validators.Add(ValidatePositiveInteger);
 
+            AffectedTestsEnabled = EnvironmentVariableParser.ParseBool(
+                Environment.GetEnvironmentVariable(EnableAffectedTestsEnvironmentVariable),
+                defaultValue: false);
+
+            CollectTestMapOption = new(CollectTestMapOptionName)
+            {
+                Description = CommandDefinitionStrings.CmdCollectTestMapDescription,
+                Arity = ArgumentArity.Zero,
+                Hidden = !AffectedTestsEnabled,
+            };
+
+            AffectedTestsOption = new(AffectedTestsOptionName)
+            {
+                Description = CommandDefinitionStrings.CmdAffectedTestsDescription,
+                Arity = ArgumentArity.Zero,
+                Hidden = !AffectedTestsEnabled,
+            };
+
             Options.Add(ProjectOrSolutionOption);
             Options.Add(SolutionOption);
             Options.Add(TestModulesFilterOption);
@@ -228,7 +259,33 @@ public MicrosoftTestingPlatform()
             Options.Add(NoLaunchProfileArgumentsOption);
             Options.Add(DeviceOption);
             Options.Add(ListDevicesOption);
+            Options.Add(CollectTestMapOption);
+            Options.Add(AffectedTestsOption);
             Options.Add(MTPTargetOption);
+
+            Validators.Add(commandResult =>
+            {
+                bool collectTestMap = commandResult.HasOption(CollectTestMapOption);
+                bool affectedTests = commandResult.HasOption(AffectedTestsOption);
+                if (!AffectedTestsEnabled && (collectTestMap || affectedTests))
+                {
+                    commandResult.AddError(string.Format(
+                        CommandDefinitionStrings.CmdAffectedTestsFeatureDisabled,
+                        EnableAffectedTestsEnvironmentVariable));
+                }
+                else if (collectTestMap && affectedTests)
+                {
+                    commandResult.AddError(CommandDefinitionStrings.CmdAffectedTestsOptionsMutuallyExclusive);
+                }
+                else if (collectTestMap && commandResult.HasOption(MaxParallelTestModulesOption))
+                {
+                    commandResult.AddError(CommandDefinitionStrings.CmdCollectTestMapCannotRunModulesInParallel);
+                }
+                else if (collectTestMap && commandResult.HasOption(MinimumExpectedTestsOption))
+                {
+                    commandResult.AddError(CommandDefinitionStrings.CmdCollectTestMapCannotRequireMinimumTests);
+                }
+            });
         }
 
         public IEnumerable<Action<HelpContext>> CustomHelpLayout()