fix(backend): Fix Integration Test database provider conflict with environment-aware DI

Implement environment-aware dependency injection to resolve EF Core provider conflict
in Integration Tests. The issue was caused by both PostgreSQL and InMemory providers
being registered in the same service provider.

Changes:
- Modified Identity Module DependencyInjection to skip PostgreSQL DbContext registration in Testing environment
- Modified ProjectManagement Module ModuleExtensions with same environment check
- Updated Program.cs to pass IHostEnvironment to both module registration methods
- Added Microsoft.Extensions.Hosting.Abstractions package to Identity.Infrastructure project
- Updated ColaFlowWebApplicationFactory to set Testing environment and register InMemory databases
- Simplified WebApplicationFactory by removing complex RemoveAll logic

Results:
- All 31 Integration Tests now run (previously only 1 ran)
- No EF Core provider conflict errors
- 23 tests pass, 8 tests fail (failures are business logic issues, not infrastructure)
- Production environment still uses PostgreSQL as expected

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

colaflow-api/src/ColaFlow.API/Extensions/ModuleExtensions.cs

@@ -6,6 +6,7 @@ using ColaFlow.Modules.ProjectManagement.Application.Commands.CreateProject;
 using ColaFlow.Modules.ProjectManagement.Domain.Repositories;
 using ColaFlow.Modules.ProjectManagement.Infrastructure.Persistence;
 using ColaFlow.Modules.ProjectManagement.Infrastructure.Repositories;
+using Microsoft.Extensions.Hosting;
 
 namespace ColaFlow.API.Extensions;
 
@@ -19,12 +20,18 @@ public static class ModuleExtensions
     /// </summary>
     public static IServiceCollection AddProjectManagementModule(
         this IServiceCollection services,
-        IConfiguration configuration)
+        IConfiguration configuration,
+        IHostEnvironment? environment = null)
+    {
+        // Only register PostgreSQL DbContext in non-Testing environments
+        // In Testing environment, WebApplicationFactory will register InMemory provider
+        if (environment == null || environment.EnvironmentName != "Testing")
         {
             // Register DbContext
             var connectionString = configuration.GetConnectionString("PMDatabase");
             services.AddDbContext<PMDbContext>(options =>
                 options.UseNpgsql(connectionString));
+        }
 
         // Register repositories
         services.AddScoped<IProjectRepository, ProjectRepository>();

colaflow-api/src/ColaFlow.API/Program.cs

@@ -10,11 +10,11 @@ using System.Text;
 var builder = WebApplication.CreateBuilder(args);
 
 // Register ProjectManagement Module
-builder.Services.AddProjectManagementModule(builder.Configuration);
+builder.Services.AddProjectManagementModule(builder.Configuration, builder.Environment);
 
 // Register Identity Module
 builder.Services.AddIdentityApplication();
-builder.Services.AddIdentityInfrastructure(builder.Configuration);
+builder.Services.AddIdentityInfrastructure(builder.Configuration, builder.Environment);
 
 // Add controllers
 builder.Services.AddControllers();
@@ -107,3 +107,6 @@ app.UseAuthorization();
 app.MapControllers();
 
 app.Run();
+
+// Make the implicit Program class public for integration tests
+public partial class Program { }

colaflow-api/src/Modules/Identity/ColaFlow.Modules.Identity.Infrastructure/ColaFlow.Modules.Identity.Infrastructure.csproj

@@ -6,12 +6,14 @@
 
   <ItemGroup>
     <PackageReference Include="BCrypt.Net-Next" Version="4.0.3" />
+    <PackageReference Include="Microsoft.AspNetCore.Hosting.Abstractions" Version="2.3.0" />
     <PackageReference Include="Microsoft.AspNetCore.Http" Version="2.3.0" />
     <PackageReference Include="Microsoft.EntityFrameworkCore" Version="9.0.10" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="9.0.10">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
+    <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" Version="9.0.10" />
     <PackageReference Include="Microsoft.Extensions.Http" Version="9.0.10" />
     <PackageReference Include="Microsoft.IdentityModel.Tokens" Version="8.14.0" />
     <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="9.0.4" />

colaflow-api/src/Modules/Identity/ColaFlow.Modules.Identity.Infrastructure/DependencyInjection.cs

@@ -6,6 +6,7 @@ using ColaFlow.Modules.Identity.Infrastructure.Services;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
 
 namespace ColaFlow.Modules.Identity.Infrastructure;
 
@@ -13,13 +14,19 @@ public static class DependencyInjection
 {
     public static IServiceCollection AddIdentityInfrastructure(
         this IServiceCollection services,
-        IConfiguration configuration)
+        IConfiguration configuration,
+        IHostEnvironment? environment = null)
+    {
+        // Only register PostgreSQL DbContext in non-Testing environments
+        // In Testing environment, WebApplicationFactory will register InMemory provider
+        if (environment == null || environment.EnvironmentName != "Testing")
         {
             // DbContext (using connection string)
             services.AddDbContext<IdentityDbContext>(options =>
                 options.UseNpgsql(
                     configuration.GetConnectionString("DefaultConnection"),
                     b => b.MigrationsAssembly(typeof(IdentityDbContext).Assembly.FullName)));
+        }
 
         // Tenant Context (Scoped - one instance per request)
         services.AddScoped<ITenantContext, TenantContext>();

colaflow-api/tests/Modules/Identity/ColaFlow.Modules.Identity.IntegrationTests/Infrastructure/ColaFlowWebApplicationFactory.cs

@@ -0,0 +1,132 @@
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
+using Microsoft.Extensions.Hosting;
+using ColaFlow.Modules.Identity.Infrastructure.Persistence;
+using ColaFlow.Modules.ProjectManagement.Infrastructure.Persistence;
+
+namespace ColaFlow.Modules.Identity.IntegrationTests.Infrastructure;
+
+/// <summary>
+/// Custom WebApplicationFactory for ColaFlow Integration Tests
+/// Supports both In-Memory and Real PostgreSQL databases
+/// </summary>
+public class ColaFlowWebApplicationFactory : WebApplicationFactory<Program>
+{
+    private readonly bool _useInMemoryDatabase;
+    private readonly string? _testDatabaseName;
+
+    public ColaFlowWebApplicationFactory(bool useInMemoryDatabase = true, string? testDatabaseName = null)
+    {
+        _useInMemoryDatabase = useInMemoryDatabase;
+        _testDatabaseName = testDatabaseName ?? $"TestDb_{Guid.NewGuid()}";
+    }
+
+    protected override void ConfigureWebHost(IWebHostBuilder builder)
+    {
+        // Set environment to Testing - this prevents PostgreSQL DbContext registration in modules
+        builder.UseEnvironment("Testing");
+
+        // Configure test-specific settings
+        builder.ConfigureAppConfiguration((context, config) =>
+        {
+            // Clear existing connection strings to prevent PostgreSQL registration
+            config.Sources.Clear();
+
+            // Add minimal config for testing
+            config.AddInMemoryCollection(new Dictionary<string, string?>
+            {
+                ["ConnectionStrings:DefaultConnection"] = "",
+                ["ConnectionStrings:PMDatabase"] = "",
+                ["Jwt:SecretKey"] = "test-secret-key-for-integration-tests-minimum-32-characters",
+                ["Jwt:Issuer"] = "ColaFlow.Test",
+                ["Jwt:Audience"] = "ColaFlow.Test",
+                ["Jwt:AccessTokenExpirationMinutes"] = "15",
+                ["Jwt:RefreshTokenExpirationDays"] = "7"
+            });
+        });
+
+        builder.ConfigureServices(services =>
+        {
+            // Register test databases (modules won't register PostgreSQL due to Testing environment)
+            if (_useInMemoryDatabase)
+            {
+                // Use In-Memory Database for fast, isolated tests
+                // IMPORTANT: Share the same database name for cross-context data consistency
+                services.AddDbContext<IdentityDbContext>(options =>
+                {
+                    options.UseInMemoryDatabase(_testDatabaseName!);
+                    options.EnableSensitiveDataLogging();
+                });
+
+                services.AddDbContext<PMDbContext>(options =>
+                {
+                    options.UseInMemoryDatabase(_testDatabaseName!);
+                    options.EnableSensitiveDataLogging();
+                });
+            }
+            else
+            {
+                // Use Real PostgreSQL for integration tests
+                var connectionString = $"Host=localhost;Port=5432;Database=colaflow_test_{_testDatabaseName};Username=postgres;Password=postgres";
+
+                services.AddDbContext<IdentityDbContext>(options =>
+                {
+                    options.UseNpgsql(connectionString);
+                    options.EnableSensitiveDataLogging();
+                });
+
+                services.AddDbContext<PMDbContext>(options =>
+                {
+                    options.UseNpgsql(connectionString);
+                    options.EnableSensitiveDataLogging();
+                });
+            }
+        });
+    }
+
+    // Override CreateHost to initialize databases after the host is created
+    protected override IHost CreateHost(IHostBuilder builder)
+    {
+        var host = base.CreateHost(builder);
+
+        // Initialize databases after host is created
+        using var scope = host.Services.CreateScope();
+        var services = scope.ServiceProvider;
+
+        try
+        {
+            // Initialize Identity database
+            var identityDb = services.GetRequiredService<IdentityDbContext>();
+            if (_useInMemoryDatabase)
+            {
+                identityDb.Database.EnsureCreated();
+            }
+            else
+            {
+                identityDb.Database.Migrate();
+            }
+
+            // Initialize ProjectManagement database
+            var pmDb = services.GetRequiredService<PMDbContext>();
+            if (_useInMemoryDatabase)
+            {
+                pmDb.Database.EnsureCreated();
+            }
+            else
+            {
+                pmDb.Database.Migrate();
+            }
+        }
+        catch (Exception ex)
+        {
+            Console.WriteLine($"Error initializing test database: {ex.Message}");
+            throw;
+        }
+
+        return host;
+    }
+}