Add BuildServiceProvider analyzer rule (#192)

* feat: add BuildServiceProvider analyzer rule

* Update AG0041LogTemplateAnalyzer.cs (#193)

* Update AG0041LogTemplateAnalyzer.cs

* Create AG0041.md

* feat: add BuildServiceProvider analyzer rule

* docs: update docs for the rule.

* chore: remove comments

* Add examples with minimal API which is more common

* Update error message with more explanation

---------

Co-authored-by: Joel Dickson <[email protected]>

Author: rannes

doc/AG0043.md

@@ -0,0 +1,121 @@
+# AG0043: BuildServiceProvider should not be used in production code
+
+## Problem Description
+Using `BuildServiceProvider()` in production code can lead to memory leaks and other issues because it creates a new container. This is especially problematic when called repeatedly, such as in request processing scenarios.
+
+## Rule Details
+This rule raises an issue when `BuildServiceProvider()` is called on `IServiceCollection` instances.
+
+### Noncompliant Code Examples
+
+#### Traditional ASP.NET Core
+```csharp
+public void ConfigureServices(IServiceCollection services)
+{
+    services.AddTransient<IMyService, MyService>();
+    var serviceProvider = services.BuildServiceProvider(); // Noncompliant
+    var myService = serviceProvider.GetService<IMyService>();
+}
+```
+
+#### Minimal API
+```csharp
+var builder = WebApplication.CreateBuilder(args);
+
+builder.Services.AddTransient<IMyService, MyService>();
+
+var app = builder.Build();
+
+app.MapGet("/", () => 
+{
+    var serviceProvider = app.Services.BuildServiceProvider(); // Noncompliant
+    var myService = serviceProvider.GetService<IMyService>();
+    return myService.GetMessage();
+});
+
+app.Run();
+```
+
+### Compliant Solutions
+
+#### Traditional ASP.NET Core
+```csharp
+public class Startup
+{
+    public void ConfigureServices(IServiceCollection services)
+    {
+        services.AddTransient<IMyService, MyService>();
+        // Let ASP.NET Core build the service provider
+    }
+    public void Configure(IApplicationBuilder app, IMyService myService)
+    {
+        // Services are injected by the framework
+    }
+}
+```
+
+#### Minimal API
+```csharp
+var builder = WebApplication.CreateBuilder(args);
+
+builder.Services.AddTransient<IMyService, MyService>();
+
+var app = builder.Build();
+
+app.MapGet("/", (IMyService myService) => myService.GetMessage());
+
+app.Run();
+
+// Service interfaces and implementations
+public interface IMyService
+{
+    string GetMessage();
+}
+
+public class MyService : IMyService
+{
+    public string GetMessage() => "Hello from MyService!";
+}
+```
+
+## Why is this an Issue?
+1. **Memory Leaks**: Each call to `BuildServiceProvider()` creates a new dependency injection container, which holds references to all registered services. If called repeatedly (e.g., during request processing), this leads to memory leaks.
+2. **Performance Impact**: Creating new service providers is computationally expensive and can impact application performance.
+3. **Singleton Duplication**: Multiple service providers can result in multiple instances of services that should be singletons.
+
+## Exceptions
+`BuildServiceProvider()` may be acceptable in the following scenarios:
+- Unit tests where a full DI container is needed
+- Development-time configuration validation
+- Tools and utilities that run outside the normal application lifecycle
+
+## How to Fix It
+1. In ASP.NET Core applications:
+    - Let the framework handle service provider creation
+    - Use constructor injection to obtain dependencies
+    - Use `IServiceScope` for creating scoped service providers when needed
+    - `HttpContext` and other services have methods like `RequestServices.GetService<T>()` to get scoped services
+2. For configuration validation:
+   ```csharp
+   public void ConfigureServices(IServiceCollection services)
+   {
+       services.AddTransient<IMyService, MyService>();
+       // Only in development
+       if (Environment.IsDevelopment())
+       {
+           // Validate service registration
+           var serviceProvider = services.BuildServiceProvider(validateScopes: true);
+           serviceProvider.Dispose();
+       }
+   }
+   ```
+
+## Benefits
+- Prevents memory leaks
+- Improves application performance
+- Ensures proper singleton behavior
+- Maintains proper service scoping
+
+## References
+- [ASP.NET Core Dependency Injection Best Practices](https://docs.microsoft.com/en-us/aspnet/core/fundamentals/dependency-injection#service-lifetimes)
+- [Dependency injection in ASP.NET Core](https://docs.microsoft.com/en-us/aspnet/core/fundamentals/dependency-injection)

src/Agoda.Analyzers.Test/AgodaCustom/AG0043UnitTests.cs

@@ -0,0 +1,96 @@
+using System.Threading.Tasks;
+using Agoda.Analyzers.AgodaCustom;
+using Agoda.Analyzers.Test.Helpers;
+using Microsoft.CodeAnalysis.Diagnostics;
+using NUnit.Framework;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Agoda.Analyzers.Test.AgodaCustom;
+
+[TestFixture]
+class AG0043UnitTests : DiagnosticVerifier
+{
+    protected override DiagnosticAnalyzer DiagnosticAnalyzer => new AG0043NoBuildServiceProvider();
+
+    protected override string DiagnosticId => AG0043NoBuildServiceProvider.DIAGNOSTIC_ID;
+
+    [Test]
+    public async Task BuildServiceProvider_Used_RaisesDiagnostic()
+    {
+        var services = new ServiceCollection();
+        services.BuildServiceProvider();
+        
+        var code = new CodeDescriptor
+        {
+            References = new[]
+            {
+                typeof(ServiceCollection).Assembly, 
+                typeof(ServiceProvider).Assembly, 
+                typeof(IServiceCollection).Assembly
+            },
+            Code = @"
+                    using Microsoft.Extensions.DependencyInjection;
+                    
+                    public class Program
+                    {
+                        public static void Main()
+                        {
+                            var services = new ServiceCollection();
+                            var provider = services.BuildServiceProvider();
+                        }
+                    }"
+        };
+        
+        await VerifyDiagnosticsAsync(code, new DiagnosticLocation(9, 53));
+    }
+
+    [Test]
+    public async Task OtherMethod_NoDiagnostic()
+    {
+        var code = new CodeDescriptor
+        {
+            References = new[] {typeof(ServiceCollection).Assembly},
+            Code = @"
+                    using Microsoft.Extensions.DependencyInjection;
+
+                    class TestClass
+                    {
+                        public void ConfigureServices()
+                        {
+                            var services = new ServiceCollection();
+                            services.AddSingleton<object>();
+                        }
+                    }"
+        };
+        
+        await VerifyDiagnosticsAsync(code, EmptyDiagnosticResults);
+    }
+    
+    [Test]
+    public async Task BuildServiceProvider_WhenChaining_RaiseDiagnostic()
+    {
+        var code = new CodeDescriptor
+        {
+            References = new[]
+            {
+                typeof(ServiceCollection).Assembly, 
+                typeof(ServiceProvider).Assembly, 
+                typeof(IServiceCollection).Assembly
+            },
+            Code = @"
+                    using Microsoft.Extensions.DependencyInjection;
+                    
+                    public class Program
+                    {
+                        public static void Main()
+                        {
+                            var provider = new ServiceCollection()
+                                .AddSingleton<object>()
+                                .BuildServiceProvider();
+                        }
+                    }"
+        };
+        
+        await VerifyDiagnosticsAsync(code, new DiagnosticLocation(10, 34));
+    }
+}

src/Agoda.Analyzers/AgodaCustom/AG0043NoBuildServiceProvider.cs

@@ -0,0 +1,94 @@
+using System.Collections.Immutable;
+using System.Linq;
+using Agoda.Analyzers.Helpers;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Diagnostics;
+
+namespace Agoda.Analyzers.AgodaCustom
+{
+    [DiagnosticAnalyzer(LanguageNames.CSharp)]
+    public class AG0043NoBuildServiceProvider : DiagnosticAnalyzer
+    {
+        public const string DIAGNOSTIC_ID = "AG0043";
+
+        private static readonly LocalizableString Title = new LocalizableResourceString(
+            nameof(CustomRulesResources.AG0043Title),
+            CustomRulesResources.ResourceManager,
+            typeof(CustomRulesResources));
+
+        private static readonly LocalizableString MessageFormat = new LocalizableResourceString(
+            nameof(CustomRulesResources.AG0043Title),
+            CustomRulesResources.ResourceManager,
+            typeof(CustomRulesResources));
+
+        private static readonly LocalizableString Description
+            = DescriptionContentLoader.GetAnalyzerDescription(nameof(AG0043NoBuildServiceProvider));
+
+        private static readonly DiagnosticDescriptor Descriptor = new DiagnosticDescriptor(
+            DIAGNOSTIC_ID,
+            Title,
+            MessageFormat,
+            AnalyzerCategory.CustomQualityRules,
+            DiagnosticSeverity.Error,
+            AnalyzerConstants.EnabledByDefault,
+            Description,
+            "https://github.com/agoda-com/AgodaAnalyzers/blob/master/doc/AG0043.md",
+            WellKnownDiagnosticTags.EditAndContinue);
+
+        public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(Descriptor);
+
+        public override void Initialize(AnalysisContext context)
+        {
+            context.EnableConcurrentExecution();
+            context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
+            context.RegisterSyntaxNodeAction(AnalyzeNode, SyntaxKind.InvocationExpression);
+        }
+
+        private static void AnalyzeNode(SyntaxNodeAnalysisContext context)
+        {
+            var invocationExpr = (InvocationExpressionSyntax)context.Node;
+
+            if (!(invocationExpr.Expression is MemberAccessExpressionSyntax memberAccessExpr))
+                return;
+
+            if (memberAccessExpr.Name.Identifier.ValueText != "BuildServiceProvider")
+                return;
+
+            var methodSymbol = context.SemanticModel.GetSymbolInfo(invocationExpr).Symbol as IMethodSymbol;
+            if (methodSymbol == null)
+                return;
+
+            if (!methodSymbol.ContainingNamespace.ToDisplayString()
+                    .StartsWith("Microsoft.Extensions.DependencyInjection"))
+                return;
+
+            var containingType = methodSymbol.ContainingType;
+            if (containingType == null)
+                return;
+
+            var isServiceCollectionExtension = containingType
+                .GetTypeMembers()
+                .SelectMany(t => t.GetMembers())
+                .OfType<IMethodSymbol>()
+                .Any(m => m.Parameters.Length > 0 &&
+                          m.Parameters[0].Type.ToDisplayString() ==
+                          "Microsoft.Extensions.DependencyInjection.IServiceCollection");
+
+            var expressionType = context.SemanticModel.GetTypeInfo(memberAccessExpr.Expression).Type;
+            var isExpressionServiceCollection = expressionType != null &&
+                                                (expressionType.AllInterfaces.Any(i =>
+                                                     i.ToDisplayString() ==
+                                                     "Microsoft.Extensions.DependencyInjection.IServiceCollection") ||
+                                                 expressionType.ToDisplayString() ==
+                                                 "Microsoft.Extensions.DependencyInjection.IServiceCollection");
+
+            if (isServiceCollectionExtension || isExpressionServiceCollection)
+            {
+                var diagnostic = Diagnostic.Create(Descriptor, memberAccessExpr.Name.GetLocation());
+                context.ReportDiagnostic(diagnostic);
+            }
+        }
+    }
+}

src/Agoda.Analyzers/AgodaCustom/CustomRulesResources.Designer.cs

@@ -260,4 +260,7 @@ One exception is logging, where it can be useful to see the exact DC / cluster /
   <data name="AG0041Title" xml:space="preserve">
     <value>You are using either an interpolated string or string concatenation in your logs, change these to the message template format to preserve structure in your logs</value>
   </data>
-</root>
+  <data name="AG0043Title" xml:space="preserve">
+    <value>BuildServiceProvider detected in request processing code. This may cause memory leaks. Remove the BuildServiceProvider() call and let the framework manage the service provider lifecycle.</value>
+  </data>
+</root>