Merge pull request #15 from supabase-community/feat/error

feat: Add support for triggering error for PostgREST methods.

Author: dshukertjr

README.md

@@ -139,6 +139,142 @@ void main() {
 }
 ```
 
+### Mocking Errors
+
+You can simulate error scenarios by configuring an error trigger callback. This is useful for testing how your application handles various error conditions:
+
+```dart
+void main() {
+  late final SupabaseClient mockSupabase;
+  late final MockSupabaseHttpClient mockHttpClient;
+
+  setUp(() {
+    // Configure error trigger
+    mockHttpClient = MockSupabaseHttpClient(
+      postgrestExceptionTrigger: (schema, table, data, type) {
+        // Simulate unique constraint violation on email
+        if (table == 'users' && type == RequestType.insert) {
+          throw PostgrestException(
+            message: 'duplicate key value violates unique constraint "users_email_key"',
+            code: '23505', // Postgres unique violation code
+          );
+        }
+        
+        // Simulate permission error for certain operations
+        if (table == 'private_data' && type == RequestType.select) {
+          throw PostgrestException(
+            message: 'permission denied for table private_data',
+            code: '42501', // Postgres permission denied code
+          );
+        }
+      },
+    );
+
+    mockSupabase = SupabaseClient(
+      'https://mock.supabase.co',
+      'fakeAnonKey',
+      httpClient: mockHttpClient,
+    );
+  });
+
+  test('handles duplicate email error', () async {
+    expect(
+      () => mockSupabase.from('users').insert({
+        'email': '[email protected]',
+        'name': 'Test User'
+      }),
+      throwsA(isA<PostgrestException>()),
+    );
+  });
+}
+```
+
+### RPC Functions
+
+You can mock Remote Procedure Call (RPC) functions by registering them with the mock client:
+
+```dart
+void main() {
+  late final SupabaseClient mockSupabase;
+  late final MockSupabaseHttpClient mockHttpClient;
+
+  setUp(() {
+    mockHttpClient = MockSupabaseHttpClient();
+
+    // Register mock RPC functions
+    mockHttpClient.registerRpcFunction(
+      'get_user_status',
+      (params, tables) => {'status': 'active', 'last_seen': '2024-03-20'},
+    );
+
+    mockHttpClient.registerRpcFunction(
+      'calculate_total',
+      (params, tables) {
+        final amount = params['amount'] as num;
+        final tax = params['tax_rate'] as num;
+        return {
+          'total': amount + (amount * tax),
+          'tax_amount': amount * tax,
+        };
+      },
+    );
+
+    mockSupabase = SupabaseClient(
+      'https://mock.supabase.co',
+      'fakeAnonKey',
+      httpClient: mockHttpClient,
+    );
+  });
+
+  test('calls RPC function with parameters', () async {
+    final result = await mockSupabase.rpc(
+      'calculate_total',
+      params: {'amount': 100, 'tax_rate': 0.1},
+    );
+
+    expect(result, {
+      'total': 110.0,
+      'tax_amount': 10.0,
+    });
+  });
+
+  test('mocks complex RPC function using database state', () async {
+    // Insert some test data
+    await mockSupabase.from('orders').insert([
+      {'id': 1, 'user_id': 123, 'amount': 100},
+      {'id': 2, 'user_id': 123, 'amount': 200},
+    ]);
+
+    // Register RPC that uses the mock database state
+    mockHttpClient.registerRpcFunction(
+      'get_user_total_orders',
+      (params, tables) {
+        final userId = params['user_id'];
+        final orders = tables['public.orders'] as List<Map<String, dynamic>>;
+        
+        final userOrders = orders.where((order) => order['user_id'] == userId);
+        final total = userOrders.fold<num>(
+          0,
+          (sum, order) => sum + (order['amount'] as num),
+        );
+
+        return {'total_orders': userOrders.length, 'total_amount': total};
+      },
+    );
+
+    final result = await mockSupabase.rpc(
+      'get_user_total_orders',
+      params: {'user_id': 123},
+    );
+
+    expect(result, {
+      'total_orders': 2,
+      'total_amount': 300,
+    });
+  });
+}
+```
+
 ## Current Limitations
 
 - The mock Supabase client does not know the table schema. This means that it does not know if the inserted mock data is a referenced table data, or just a array/JSON object. This could potentially return more data than you construct a mock data with more than one referenced table.
@@ -154,7 +290,6 @@ void main() {
 - count and head requests are not supported.
 - aggregate functions are not supported.
 - Respect nullsFirst on ordering is not supported.
-- rpc support is not supported.
 - The errors thrown by the mock Supabase client is not the same as the actual Supabase client.
 - The mock Supabase client does not support auth, realtime, storage, or calling edge functions.
     - You can either mock those using libraries like [mockito](https://pub.dev/packages/mockito) or use the Supabase CLI to do a full integration testing. You could use our [GitHub actions](https://github.com/supabase/setup-cli) to do that.