insert + select().single() returns List instead of Map

[augustogiavedoni]

Bug report

Describe the bug

Calling .insert(...).select().single() throws a runtime type error because the mock client returns a List instead of a single Map when a single row is expected.

Error

type 'List<dynamic>' is not a subtype of type 'Map<dynamic, dynamic>'
package:postgrest/src/postgrest_builder.dart 241:34  PostgrestBuilder._parseResponse
package:postgrest/src/postgrest_builder.dart 174:14  PostgrestBuilder._execute

To Reproduce

import 'package:test/test.dart';
import 'package:supabase/supabase.dart';
import 'package:mock_supabase_http_client/mock_supabase_http_client.dart';

void main() {
  late SupabaseClient client;
  late MockSupabaseHttpClient mockHttp;

  setUp(() {
    mockHttp = MockSupabaseHttpClient();
    client = SupabaseClient('https://mock.supabase.co', 'anon', httpClient: mockHttp);
  });

  tearDown(() => mockHttp.reset());

  test('insert + select().single() returns a Map', () async {
    final row = {'id': 1, 'title': 'Test expense', 'amount': 1234};

    final result = await client.from('expenses').insert(row).select().single();

    expect(result, isA<Map<String, dynamic>>());
    expect(result['id'], 1);
  });
}

Expected behavior

When chaining .single() after .select(), the mock client should return a single object (Map<String, dynamic>) for a single-row insert, matching Supabase/PostgREST behavior, not a List.

Screenshots

N/A

System information

• OS: macOS (Apple Silicon)
• Version of mock_supabase_http_client: 0.0.3+2
• Browser (if applies): N/A
• Version of supabase-js: N/A
• Version of Node.js: N/A

Additional context

The failure happens only when .single() is used. Without .single(), the call returns a List and succeeds, but that doesn’t mimic PostgREST’s single-object response.

[Roman-Dzerkal]

Same issue