[FaultInjection] FaultInjection: Adds XML documentation, stylecop.json, and updates test packages (#5677)

## Summary

This PR adds missing XML documentation, the stylecop.json configuration
file, and updates test framework packages.

### Changes

**1. Add XML documentation to undocumented public members (#5661)**
- `FaultInjector` class-level summary
- `FaultInjector.GetFaultInjectionClientOptions()` 
- `FaultInjector.GetApplicationContext()`
- `FaultInjectionServerErrorResultBuilder.WithSuppressServiceRequest()`
- `FaultInjectionServerErrorResultBuilder.WithInjectionRate()`
- `FaultInjectionApplicationContext` class-level summary
- `FaultInjectionApplicationContext.GetAllRuleExecutionsByRuleId()`
- `FaultInjectionApplicationContext.GetAllRuleExecutionsByActivityId()`
- `FaultInjectionApplicationContext.TryGetRuleExecutionsByRuleId()`

**2. Add missing `stylecop.json` (#5662)**
- Created `stylecop.json` in `FaultInjection/src/` matching the main
SDK's configuration.
- The csproj already referenced this file via `<AdditionalFiles>` but it
didn't exist.

**3. Update test framework packages (#5668)**
- `Microsoft.NET.Test.Sdk`: 17.1.0 → 17.12.0
- `MSTest.TestAdapter`: 2.2.8 → 3.7.3
- `MSTest.TestFramework`: 2.2.8 → 3.7.3
- `coverlet.collector`: 3.1.2 → 6.0.4

### Testing
- Build verified locally with `dotnet build`

Parent tracking issue: #5652

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Kiran Kumar Kolli <kirankk@microsoft.com>

Author: 3 people

Microsoft.Azure.Cosmos/FaultInjection/src/FaultInjectionServerErrorResultBuilder.cs

@@ -62,12 +62,23 @@ public FaultInjectionServerErrorResultBuilder WithDelay(TimeSpan delay)
             return this;
         }
 
+        /// <summary>
+        /// Sets whether to suppress the service request when the fault is injected.
+        /// </summary>
+        /// <param name="suppressServiceRequest">If true, the service request will be suppressed.</param>
+        /// <returns>The current <see cref="FaultInjectionServerErrorResultBuilder"/>.</returns>
         public FaultInjectionServerErrorResultBuilder WithSuppressServiceRequest(bool suppressServiceRequest)
         {
             this.suppressServiceRequest = suppressServiceRequest;
             return this;
         }
 
+        /// <summary>
+        /// Sets the injection rate, which determines the probability that the fault will be injected.
+        /// Must be a value in the range (0, 1]. Default is 1 (100%).
+        /// </summary>
+        /// <param name="injectionRate">The injection rate, in the range (0, 1].</param>
+        /// <returns>The current <see cref="FaultInjectionServerErrorResultBuilder"/>.</returns>
         public FaultInjectionServerErrorResultBuilder WithInjectionRate(double injectionRate)
         {
             if (injectionRate <= 0 || injectionRate > 1)

Microsoft.Azure.Cosmos/FaultInjection/src/FaultInjector.cs

@@ -7,6 +7,9 @@ namespace Microsoft.Azure.Cosmos.FaultInjection
     using System.Collections.Generic;
     using Microsoft.Azure.Documents.FaultInjection;
 
+    /// <summary>
+    /// Manages fault injection rules and provides access to fault injection client options and diagnostics.
+    /// </summary>
     public class FaultInjector : IFaultInjector
     {
         private readonly ChaosInterceptorFactory chaosInterceptorFactory;
@@ -16,6 +19,11 @@ public FaultInjector(List<FaultInjectionRule> rules)
             this.chaosInterceptorFactory = new ChaosInterceptorFactory(rules);
         }
 
+        /// <summary>
+        /// Configures the provided <see cref="CosmosClientOptions"/> with the fault injection interceptor.
+        /// </summary>
+        /// <param name="clientOptions">The <see cref="CosmosClientOptions"/> to configure.</param>
+        /// <returns>The configured <see cref="CosmosClientOptions"/>.</returns>
         public CosmosClientOptions GetFaultInjectionClientOptions(CosmosClientOptions clientOptions)
         {
             clientOptions.ChaosInterceptorFactory = this.chaosInterceptorFactory;
@@ -33,7 +41,10 @@ public CosmosClientOptions GetFaultInjectionClientOptions(CosmosClientOptions cl
             return this.chaosInterceptorFactory.ChaosInterceptor?.GetFaultInjectionRuleId(activityId);
         }
 
-        //Get Application Context
+        /// <summary>
+        /// Gets the <see cref="FaultInjectionApplicationContext"/> containing rule execution tracking data.
+        /// </summary>
+        /// <returns>The <see cref="FaultInjectionApplicationContext"/>, or null if not yet initialized.</returns>
         public FaultInjectionApplicationContext? GetApplicationContext()
         {
             return this.chaosInterceptorFactory.ChaosInterceptor?.GetApplicationContext();

Microsoft.Azure.Cosmos/FaultInjection/src/implementation/FaultInjectionApplicationContext.cs

@@ -6,6 +6,10 @@ namespace Microsoft.Azure.Cosmos.FaultInjection
     using System;
     using System.Collections.Concurrent;
 
+    /// <summary>
+    /// Provides tracking and observability for fault injection rule executions, 
+    /// including lookups by rule ID and activity ID.
+    /// </summary>
     public class FaultInjectionApplicationContext
     { 
 
@@ -44,16 +48,30 @@ internal void AddRuleExecution(string ruleId, Guid activityId)
             return this.values;
         }
 
+        /// <summary>
+        /// Gets all rule executions indexed by rule ID.
+        /// </summary>
+        /// <returns>A <see cref="ConcurrentDictionary{TKey, TValue}"/> mapping rule IDs to their executions.</returns>
         public ConcurrentDictionary<string, List<(DateTime, Guid)>> GetAllRuleExecutionsByRuleId()
         {
             return this.executionsByRuleId;
         }
 
+        /// <summary>
+        /// Gets all rule executions indexed by activity ID.
+        /// </summary>
+        /// <returns>A <see cref="ConcurrentDictionary{TKey, TValue}"/> mapping activity IDs to their executions.</returns>
         public ConcurrentDictionary<Guid, List<(DateTime, string)>> GetAllRuleExecutionsByActivityId()
         {
             return this.executionsByActivityId;
         }
 
+        /// <summary>
+        /// Tries to get rule executions for the given rule ID.
+        /// </summary>
+        /// <param name="ruleId">The rule ID to look up.</param>
+        /// <param name="execution">The list of executions for the rule, or an empty list if not found.</param>
+        /// <returns>True if executions were found, false otherwise.</returns>
         public bool TryGetRuleExecutionsByRuleId(string ruleId, out List<(DateTime, Guid)> execution)
         {
             if (this.executionsByRuleId.TryGetValue(ruleId, out List<(DateTime, Guid)>? ruleExecutions))

Microsoft.Azure.Cosmos/FaultInjection/src/stylecop.json

@@ -0,0 +1,21 @@
+{
+  "$schema": "https://raw.githubusercontent.com/DotNetAnalyzers/StyleCopAnalyzers/master/StyleCop.Analyzers/StyleCop.Analyzers/Settings/stylecop.schema.json",
+  "settings": {
+    "documentationRules": {
+      "companyName": "Microsoft",
+      "documentInternalElements": false,
+      "documentInterfaces": false,
+      "xmlHeader": false,
+      "copyrightText": "{decoration}\r\nCopyright (c) Microsoft Corporation.  All rights reserved.\r\n{decoration}",
+      "variables": {
+        "decoration": "------------------------------------------------------------"
+      }
+    },
+    "readabilityRules": {
+      "allowBuiltInTypeAliases": false
+    },
+    "orderingRules": {
+      "systemUsingDirectivesFirst": true
+    }
+  }
+}

Microsoft.Azure.Cosmos/FaultInjection/tests/FaultInjectionTests.csproj

@@ -22,10 +22,10 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.1.0" />
-    <PackageReference Include="MSTest.TestAdapter" Version="2.2.8" />
-    <PackageReference Include="MSTest.TestFramework" Version="2.2.8" />
-    <PackageReference Include="coverlet.collector" Version="3.1.2" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
+    <PackageReference Include="MSTest.TestAdapter" Version="3.7.3" />
+    <PackageReference Include="MSTest.TestFramework" Version="3.7.3" />
+    <PackageReference Include="coverlet.collector" Version="6.0.4" />
   </ItemGroup>
 
   <ItemGroup>