[5.0.3/Tests only] Updates many-to-many change tracking tests to work…

… with generated key values (#23807)

This is a precursor to fixes for #23659, #23787. This test has no product changes, it just refactors the many-to-many tests so that they can be run with generated key values, as well as running with explicit keys values like they currently do. Generated keys result in more work being done in fixup by navigations, which is where both of these issues live.

Once this is merged I will send out separate PRs to fix the two bugs.

test/EFCore.Specification.Tests/Query/ManyToManyQueryFixtureBase.cs

@@ -17,8 +17,20 @@ public abstract class ManyToManyQueryFixtureBase : SharedStoreFixtureBase<ManyTo
         public Func<DbContext> GetContextCreator()
             => () => CreateContext();
 
+        private ManyToManyData _data;
+
         public ISetSource GetExpectedData()
-            => new ManyToManyData();
+        {
+            if (_data == null)
+            {
+                using var context = CreateContext();
+                _data = new ManyToManyData(context, false);
+                context.ChangeTracker.DetectChanges();
+                context.ChangeTracker.Clear();
+            }
+
+            return _data;
+        }
 
         public IReadOnlyDictionary<Type, object> GetEntitySorters()
             => new Dictionary<Type, Func<object, object>>
@@ -329,7 +341,13 @@ protected override void OnModelCreating(ModelBuilder modelBuilder, DbContext con
                 });
         }
 
+        public virtual bool UseGeneratedKeys
+            => false;
+
         protected override void Seed(ManyToManyContext context)
-            => ManyToManyContext.Seed(context);
+        {
+            new ManyToManyData(context, UseGeneratedKeys);
+            context.SaveChanges();
+        }
     }
 }

test/EFCore.Specification.Tests/TestModels/ManyToManyModel/ManyToManyContext.cs

@@ -24,9 +24,6 @@ public ManyToManyContext(DbContextOptions options)
         public DbSet<ImplicitManyToManyB> ImplicitManyToManyBs { get; set; }
         public DbSet<GeneratedKeysLeft> GeneratedKeysLefts { get; set; }
         public DbSet<GeneratedKeysRight> GeneratedKeysRights { get; set; }
-
-        public static void Seed(ManyToManyContext context)
-            => ManyToManyData.Seed(context);
     }
 
     public static class ManyToManyContextExtensions