Startup.cs

private static void InitializeDbTestData(IApplicationBuilder app)
        {
            using (var scope = app.ApplicationServices.GetService<IServiceScopeFactory>().CreateScope())
            {
                scope.ServiceProvider.GetRequiredService<PersistedGrantDbContext>().Database.Migrate();
                scope.ServiceProvider.GetRequiredService<ConfigurationDbContext>().Database.Migrate();
                scope.ServiceProvider.GetRequiredService<ApplicationDbContext>().Database.Migrate();

                var context = scope.ServiceProvider.GetRequiredService<ConfigurationDbContext>();

                if (!context.Clients.Any())
                {
                    foreach (var client in Clients.Get())
                    {
                        context.Clients.Add(client.ToEntity());
                    }
                    context.SaveChanges();
                }

                if (!context.IdentityResources.Any())
                {
                    foreach (var resource in Resources.GetIdentityResources())
                    {
                        context.IdentityResources.Add(resource.ToEntity());
                    }
                    context.SaveChanges();
                }

                if (!context.ApiResources.Any())
                {
                    foreach (var resource in Resources.GetApiResources())
                    {
                        context.ApiResources.Add(resource.ToEntity());
                    }
                    context.SaveChanges();
                }

                var userManager = scope.ServiceProvider.GetRequiredService<UserManager<IdentityUser>>();
                if (!userManager.Users.Any())
                {
                    foreach (var testUser in Users.Get())
                    {
                        var identityUser = new IdentityUser(testUser.Username)
                        {
                            Id = testUser.SubjectId
                        };

                        userManager.CreateAsync(identityUser, "Password123!").Wait();
                        userManager.AddClaimsAsync(identityUser, testUser.Claims.ToList()).Wait();
                    }
                }
            }
        }