GH-3536: Conjoined EF Core contexts advertise a distinct DbContextUsage descriptor

src/Persistence/EfCoreTests.MultiTenancy/ConjoinedTenancy/ConjoinedDescriptorCompliance.cs

@@ -0,0 +1,137 @@
+using IntegrationTests;
+using JasperFx;
+using JasperFx.Descriptors;
+using JasperFx.Events;
+using JasperFx.MultiTenancy;
+using JasperFx.Resources;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using Shouldly;
+using Wolverine;
+using Wolverine.EntityFrameworkCore;
+using Wolverine.EntityFrameworkCore.Internals;
+using Wolverine.Postgresql;
+using Wolverine.SqlServer;
+
+namespace EfCoreTests.MultiTenancy.ConjoinedTenancy;
+
+/// <summary>
+///     GH-3536: a conjoined EF Core context must be distinguishable from a plain single-DB
+///     context in its DbContextUsage descriptor — a "Conjoined" tenancy style, DynamicMultiple
+///     cardinality, and the tenant ids from the wolverine_tenants registry surfaced on the single
+///     shared-database descriptor — so CritterWatch's descriptor-driven UI can gate/badge it.
+/// </summary>
+[Collection("multi-tenancy")]
+public abstract class ConjoinedDescriptorCompliance : IAsyncLifetime
+{
+    private readonly DatabaseEngine _engine;
+    protected IHost theHost = null!;
+    protected IDynamicTenantSource<string> theSource = null!;
+
+    protected ConjoinedDescriptorCompliance(DatabaseEngine engine)
+    {
+        _engine = engine;
+    }
+
+    public async Task InitializeAsync()
+    {
+        theHost = await Host.CreateDefaultBuilder()
+            .UseWolverine(opts =>
+            {
+                opts.Durability.Mode = DurabilityMode.Solo;
+
+                opts.Discovery.DisableConventionalDiscovery()
+                    .IncludeType<ConjoinedItemHandler>();
+
+                if (_engine == DatabaseEngine.PostgreSQL)
+                {
+                    opts.PersistMessagesWithPostgresql(Servers.PostgresConnectionString, "conjoined_descriptor");
+                    opts.Services.AddDbContextWithWolverineManagedConjoinedTenancy<ConjoinedItemsDbContext>(
+                        (builder, connectionString) => builder.UseNpgsql(connectionString.Value),
+                        AutoCreate.CreateOrUpdate);
+                }
+                else
+                {
+                    opts.PersistMessagesWithSqlServer(Servers.SqlServerConnectionString, "conjoined_descriptor");
+                    opts.Services.AddDbContextWithWolverineManagedConjoinedTenancy<ConjoinedItemsDbContext>(
+                        (builder, connectionString) => builder.UseSqlServer(connectionString.Value),
+                        AutoCreate.CreateOrUpdate);
+                }
+
+                opts.UseEntityFrameworkCoreTransactions();
+                opts.UseEntityFrameworkCoreWolverineManagedMigrations();
+                opts.Policies.AutoApplyTransactions();
+                opts.Services.AddResourceSetupOnStartup();
+                opts.PublishAllMessages().Locally();
+            }).StartAsync();
+
+        theSource = theHost.Services.GetRequiredService<IDynamicTenantSource<string>>();
+    }
+
+    public async Task DisposeAsync()
+    {
+        await theHost.StopAsync();
+        theHost.Dispose();
+    }
+
+    private async Task<DbContextUsage> createUsageAsync()
+    {
+        var source = theHost.Services.GetServices<IDbContextUsageSource>()
+            .Single(x => x.Subject == new Uri("efcore://ConjoinedItemsDbContext"));
+
+        var usage = await source.TryCreateUsage(CancellationToken.None);
+        usage.ShouldNotBeNull();
+        return usage!;
+    }
+
+    [Fact]
+    public async Task conjoined_context_advertises_conjoined_tenancy_style_and_dynamic_multiple_cardinality()
+    {
+        var usage = await createUsageAsync();
+
+        // The whole point of GH-3536: not "Single".
+        usage.TenancyStyle.ShouldBe("Conjoined");
+        usage.Database.Cardinality.ShouldBe(DatabaseCardinality.DynamicMultiple);
+
+        // Conjoined is one physical database, so there is exactly one shared descriptor.
+        usage.Database.Databases.Count.ShouldBe(1);
+    }
+
+    [Fact]
+    public async Task conjoined_descriptor_surfaces_registry_tenant_ids()
+    {
+        var tenantA = "descriptor_" + Guid.NewGuid().ToString("N").Substring(0, 8);
+        var tenantB = "descriptor_" + Guid.NewGuid().ToString("N").Substring(0, 8);
+
+        await theSource.AddTenantAsync(tenantA, CancellationToken.None);
+        await theSource.AddTenantAsync(tenantB, CancellationToken.None);
+
+        var usage = await createUsageAsync();
+
+        // Tenant ids from the wolverine_tenants registry ride on the single shared-database
+        // descriptor rather than fanning out into per-tenant database entries.
+        // Tenant ids are stored lower-cased by the registry; the ids created above are already
+        // lower-case, so a direct membership check is exact.
+        var tenantIds = usage.Database.MainDatabase!.TenantIds;
+        tenantIds.ShouldContain(tenantA);
+        tenantIds.ShouldContain(tenantB);
+
+        await theSource.RemoveTenantAsync(tenantA);
+        await theSource.RemoveTenantAsync(tenantB);
+    }
+}
+
+public class conjoined_descriptor_with_postgresql : ConjoinedDescriptorCompliance
+{
+    public conjoined_descriptor_with_postgresql() : base(DatabaseEngine.PostgreSQL)
+    {
+    }
+}
+
+public class conjoined_descriptor_with_sqlserver : ConjoinedDescriptorCompliance
+{
+    public conjoined_descriptor_with_sqlserver() : base(DatabaseEngine.SqlServer)
+    {
+    }
+}

src/Persistence/Wolverine.EntityFrameworkCore/Internals/DbContextUsageSource.cs

@@ -96,14 +96,24 @@ public TenantedDbContextUsageSource(IServiceProvider services)
         {
             var builder = _services.GetRequiredService<IDbContextBuilder<T>>();
 
+            // Conjoined multi-tenancy is one physical database shared by a dynamic
+            // list of tenants, so it doesn't fan out into a per-tenant database list
+            // the way the connection-string / data-source builders do. Detect it
+            // explicitly (GH-3536) so it advertises a distinct "Conjoined" style and
+            // carries its tenant ids on the single shared DatabaseDescriptor rather
+            // than looking identical to a plain single-DB context.
+            var isConjoined = builder is ConjoinedDbContextBuilder<T>;
+
             // Tenancy-style discriminator from the registered IDbContextBuilder
             // implementation type — keeps the badge in operator vocabulary.
-            var tenancyStyle = builder.GetType().Name switch
-            {
-                var n when n.StartsWith("TenantedDbContextBuilderByDbDataSource") => "DbDataSource",
-                var n when n.StartsWith("TenantedDbContextBuilderByConnectionString") => "ConnectionString",
-                _ => "Single"
-            };
+            var tenancyStyle = isConjoined
+                ? "Conjoined"
+                : builder.GetType().Name switch
+                {
+                    var n when n.StartsWith("TenantedDbContextBuilderByDbDataSource") => "DbDataSource",
+                    var n when n.StartsWith("TenantedDbContextBuilderByConnectionString") => "ConnectionString",
+                    _ => "Single"
+                };
 
             // Read the model + change-tracker config from the main context
             // (representative of every tenant's context).
@@ -116,6 +126,15 @@ var n when n.StartsWith("TenantedDbContextBuilderByConnectionString") => "Connec
                 .Select(DatabaseDescriptorFactory.FromDbContext)
                 .ToList();
 
+            if (isConjoined && tenantDatabases.Count > 0)
+            {
+                // Surface the tenant ids from the wolverine_tenants registry onto the
+                // single shared-database descriptor. Best-effort: a registry read
+                // hiccup must degrade to an empty tenant list, not null the whole
+                // snapshot. GH-3536.
+                await ApplyConjoinedTenantIdsAsync(tenantDatabases[0]);
+            }
+
             try
             {
                 return DbContextUsageFactory.Build(
@@ -141,6 +160,36 @@ var n when n.StartsWith("TenantedDbContextBuilderByConnectionString") => "Connec
             return null;
         }
     }
+
+    // Loads the active tenant ids for a conjoined DbContext from the wolverine_tenants
+    // registry (via the concrete ConjoinedTenantSource<T> that is also registered as the
+    // IDynamicTenantSource<string>) and stamps them onto the shared-database descriptor.
+    // Isolated in its own try/catch so a registry read failure degrades to no tenant ids
+    // rather than nulling the entire DbContextUsage. GH-3536.
+    private async Task ApplyConjoinedTenantIdsAsync(DatabaseDescriptor sharedDatabase)
+    {
+        try
+        {
+            var tenantSource = _services.GetService<ConjoinedTenantSource<T>>();
+            if (tenantSource == null)
+            {
+                return;
+            }
+
+            await tenantSource.RefreshAsync();
+
+            var tenantIds = tenantSource.AllActiveByTenant()
+                .Select(x => x.TenantId)
+                .OrderBy(x => x, StringComparer.OrdinalIgnoreCase)
+                .ToList();
+
+            sharedDatabase.TenantIds.AddRange(tenantIds);
+        }
+        catch
+        {
+            // Best-effort — leave TenantIds empty if the registry can't be read.
+        }
+    }
 }
 
 /// <summary>