Example: bytes written and read back (#289)

Author: isoos

test/bytes_example_test.dart

@@ -0,0 +1,38 @@
+import 'dart:typed_data';
+
+import 'package:postgres/postgres.dart';
+import 'package:test/test.dart';
+
+import 'docker.dart';
+
+void main() {
+  withPostgresServer('bytes example', (server) {
+    test('write and read', () async {
+      final conn = await server.newConnection();
+      await conn.execute('''
+        CREATE TABLE IF NOT EXISTS images (
+        id SERIAL PRIMARY KEY,
+        name TEXT,
+        description TEXT,
+        image BYTEA NOT NULL
+        );
+''');
+
+      final rs1 = await conn.execute(Sql.named('''
+        INSERT INTO images (name, description, image)
+        VALUES (@name, @description, @image:bytea)
+        RETURNING id
+'''), parameters: {
+        'name': 'name-1',
+        'description': 'descr-1',
+        'image': Uint8List.fromList([0, 1, 2]),
+      });
+      final id = rs1.single.single;
+
+      final rs2 = await conn
+          .execute(r'SELECT image FROM images WHERE id=$1', parameters: [id]);
+      final bytes = rs2.single.single;
+      expect(bytes, [0, 1, 2]);
+    });
+  });
+}