add DuplicateKeyException and ForeignKeyViolationException

lib/postgres.dart

@@ -15,7 +15,13 @@ import 'src/v3/protocol.dart';
 import 'src/v3/query_description.dart';
 
 export 'src/exceptions.dart'
-    show BadCertificateException, Severity, PgException, ServerException;
+    show
+        BadCertificateException,
+        Severity,
+        PgException,
+        ServerException,
+        DuplicateKeyException,
+        ForeignKeyViolationException;
 export 'src/pool/pool_api.dart';
 export 'src/replication.dart';
 export 'src/types.dart';
@@ -225,6 +231,7 @@ abstract class Connection implements Session, SessionExecutor {
   }
 
   ConnectionInfo get info;
+
   Channels get channels;
 }
 

lib/src/exceptions.dart

@@ -191,13 +191,15 @@ ServerException buildExceptionFromErrorFields(List<ErrorField> errorFields) {
 }
 
 PgException transformServerException(ServerException ex) {
-  if (ex.code == '57014') {
-    return _PgQueryCancelledException(
-      ['${ex.code}:', ex.message, ex.trace].whereType<String>().join(' '),
-      severity: ex.severity,
-    );
-  }
-  return ex;
+  return switch (ex.code) {
+    '23505' => DuplicateKeyException(ex.message, severity: ex.severity),
+    '23503' => ForeignKeyViolationException(ex.message, severity: ex.severity),
+    '57014' => _PgQueryCancelledException(
+        ['${ex.code}:', ex.message, ex.trace].whereType<String>().join(' '),
+        severity: ex.severity,
+      ),
+    _ => ex,
+  };
 }
 
 class _PgQueryCancelledException extends PgException
@@ -210,3 +212,17 @@ class _PgQueryCancelledException extends PgException
     required super.severity,
   });
 }
+
+class DuplicateKeyException extends PgException {
+  DuplicateKeyException(
+    super.message, {
+    required super.severity,
+  });
+}
+
+class ForeignKeyViolationException extends PgException {
+  ForeignKeyViolationException(
+    super.message, {
+    required super.severity,
+  });
+}

test/error_handling_test.dart

@@ -67,5 +67,46 @@ void main() {
         ),
       );
     });
+
+    test('DuplicateKeyException', () async {
+      final c = await server.newConnection();
+      await c.execute('CREATE TABLE test (id INT PRIMARY KEY);');
+      await c.execute('INSERT INTO test (id) VALUES (1);');
+      addTearDown(() async => c.execute('DROP TABLE test;'));
+
+      try {
+        await c.execute('INSERT INTO test (id) VALUES (1);');
+      } catch (e) {
+        expect(e, isA<DuplicateKeyException>());
+        expect(
+            e.toString(),
+            contains(
+                'duplicate key value violates unique constraint "test_pkey"'));
+      }
+    });
+
+    test('ForeignKeyViolationException', () async {
+      final c = await server.newConnection();
+      await c.execute('CREATE TABLE test (id INT PRIMARY KEY);');
+      await c.execute(
+          'CREATE TABLE test2 (id INT PRIMARY KEY, test_id INT REFERENCES test(id));');
+      await c.execute('INSERT INTO test (id) VALUES (1);');
+      addTearDown(() async {
+        await c.execute('DROP TABLE test2;');
+        await c.execute('DROP TABLE test;');
+      });
+
+      try {
+        await c.execute('INSERT INTO test2 (id, test_id) VALUES (1, 2);');
+      } catch (e) {
+        expect(e, isA<ForeignKeyViolationException>());
+        expect(
+          e.toString(),
+          contains(
+            'insert or update on table "test2" violates foreign key constraint "test2_test_id_fkey"',
+          ),
+        );
+      }
+    });
   });
 }

test/transaction_test.dart

@@ -700,7 +700,7 @@ void main() {
             // ignore
           }
         }),
-        throwsA(isA<ServerException>()),
+        throwsA(isA<DuplicateKeyException>()),
       );
     });
   });