Isolate console-sensitive tests from concurrent logging (#4813)

* Fix console-sensitive test isolation (#4798)

* Cover all global console capture tests (#4798)

Author: Widthdom

TESTING_GUIDE.md

@@ -0,0 +1,25 @@
+---
+category: fixed
+issues:
+  - 4798
+affected:
+  - tests/CodeIndex.Tests/AuditLogSinkTests.cs
+  - tests/CodeIndex.Tests/CliFlagSchemaTests.cs
+  - tests/CodeIndex.Tests/CommandErrorWriterTests.cs
+  - tests/CodeIndex.Tests/TestConsoleLock.cs
+  - tests/CodeIndex.Tests/ConsoleCaptureTests.cs
+  - tests/CodeIndex.Tests/DiffCommandHelpersTests.cs
+  - tests/CodeIndex.Tests/LicensePolicyTests.cs
+  - tests/CodeIndex.Tests/ProgramCliTests.cs
+  - tests/CodeIndex.Tests/SymbolExtractorTests.cs
+  - tests/CodeIndex.Tests/TestTelemetryTests.cs
+  - TESTING_GUIDE.md
+---
+
+## English
+
+- **Console-sensitive tests no longer capture concurrent request-id logs (#4798)** — every test class that owns process-global console streams now belongs to a non-parallel collection, preventing MCP request-id and global diagnostic lines from unrelated tests from entering captured stdout or stderr.
+
+## 日本語
+
+- **console-sensitive test が並行実行された request-id log を取り込まないようになりました (#4798)** — process-global な console stream を占有する全テストクラスを non-parallel collection に所属させ、無関係なテストの MCP request-id や global diagnostic 行が capture 中の stdout / stderr に混入することを防ぎます。

changelog.d/unreleased/4798.fixed.md

@@ -8,6 +8,7 @@
 
 namespace CodeIndex.Tests;
 
+[Collection("Console sensitive")]
 public class AuditLogSinkTests
 {
     [Fact]

tests/CodeIndex.Tests/AuditLogSinkTests.cs

@@ -14,6 +14,7 @@ namespace CodeIndex.Tests;
 /// #1570 で導入した「フラグ単一情報源」の契約を守るためのテスト群。スキーマと
 /// 補完スクリプト、コマンド一覧、parser-vs-completion の許容差分がずれた瞬間に失敗する。
 /// </summary>
+[Collection("Console sensitive")]
 public class CliFlagSchemaTests
 {
     [Fact]

tests/CodeIndex.Tests/CliFlagSchemaTests.cs

@@ -2,6 +2,7 @@
 
 namespace CodeIndex.Tests;
 
+[Collection("Console sensitive")]
 public class CommandErrorWriterTests
 {
     [Fact]

tests/CodeIndex.Tests/CommandErrorWriterTests.cs

@@ -6,14 +6,38 @@ namespace CodeIndex.Tests;
 public class ConsoleCaptureTests
 {
     [Fact]
-    public void ImportCancellationFixture_UsesConsoleSensitiveCollection_Issue4650()
+    public void ConsoleSensitiveCollection_AssignsGlobalCaptureClassesAndDisablesParallelization_Issues4650_4798()
     {
-        var attribute = Assert.Single(
-            typeof(ExportImportCommandRunnerCancellationTests).CustomAttributes,
-            static candidate => candidate.AttributeType == typeof(CollectionAttribute));
-        var collectionName = Assert.Single(attribute.ConstructorArguments);
+        Type[] consoleSensitiveTypes =
+        [
+            typeof(AuditLogSinkTests),
+            typeof(CliFlagSchemaTests),
+            typeof(CommandErrorWriterTests),
+            typeof(DiffCommandHelpersTests),
+            typeof(ExportImportCommandRunnerCancellationTests),
+            typeof(LicensePolicyTests),
+            typeof(ProgramCliTests),
+            typeof(SymbolExtractorTests),
+            typeof(TestTelemetryTests),
+        ];
 
-        Assert.Equal("Console sensitive", collectionName.Value);
+        foreach (var type in consoleSensitiveTypes)
+        {
+            var attribute = Assert.Single(
+                type.CustomAttributes,
+                static candidate => candidate.AttributeType == typeof(CollectionAttribute));
+            var collectionName = Assert.Single(attribute.ConstructorArguments);
+            Assert.Equal("Console sensitive", collectionName.Value);
+        }
+
+        var definition = Assert.Single(
+            typeof(ConsoleSensitiveCollection).CustomAttributes,
+            static candidate => candidate.AttributeType == typeof(CollectionDefinitionAttribute));
+        var disableParallelization = Assert.Single(
+            definition.NamedArguments,
+            static candidate => candidate.MemberName == nameof(CollectionDefinitionAttribute.DisableParallelization));
+
+        Assert.True(Assert.IsType<bool>(disableParallelization.TypedValue.Value));
     }
 
     [Fact]

tests/CodeIndex.Tests/ConsoleCaptureTests.cs

@@ -3,6 +3,7 @@
 
 namespace CodeIndex.Tests;
 
+[Collection("Console sensitive")]
 public sealed class DiffCommandHelpersTests
 {
     [Fact]

tests/CodeIndex.Tests/DiffCommandHelpersTests.cs

@@ -6,6 +6,7 @@ namespace CodeIndex.Tests;
 /// Guards licensing and distribution metadata from silently drifting back to
 /// permissive productization defaults.
 /// </summary>
+[Collection("Console sensitive")]
 public class LicensePolicyTests
 {
     private static readonly string[] CanonicalLegalNoticeFiles =

tests/CodeIndex.Tests/LicensePolicyTests.cs

@@ -16,6 +16,7 @@ namespace CodeIndex.Tests;
 /// Black-box CLI tests for Program entrypoint behavior.
 /// Program エントリポイント挙動のブラックボックステスト。
 /// </summary>
+[Collection("Console sensitive")]
 public class ProgramCliTests
 {
     [ProductionRuntimeFact]

tests/CodeIndex.Tests/ProgramCliTests.cs

@@ -16,6 +16,7 @@ namespace CodeIndex.Tests;
 /// Tests for SymbolExtractor.
 /// SymbolExtractorのテスト。
 /// </summary>
+[Collection("Console sensitive")]
 public partial class SymbolExtractorTests
 {
     private static void AssertSymbolsContain(