public void Cannot_change_connection_when_open() { var connection = new SqlConnection(SqlServerNorthwindTestStoreFactory.NorthwindConnectionString); var serviceProvider = new ServiceCollection() .AddScoped(p => connection) .AddDbContext <ConnectionInOnConfiguringContext>().BuildServiceProvider(); using (SqlServerTestStore.GetNorthwindStore()) { using var context = serviceProvider.GetRequiredService <ConnectionInOnConfiguringContext>(); context.Database.OpenConnection(); Assert.Same(connection, context.Database.GetDbConnection()); Assert.True(context.Customers.Any()); using var newConnection = new SqlConnection(SqlServerNorthwindTestStoreFactory.NorthwindConnectionString); Assert.Equal( RelationalStrings.CannotChangeWhenOpen, Assert.Throws <InvalidOperationException>(() => context.Database.SetDbConnection(newConnection)).Message); } }