feat: add alot

test/database_migration_test.dart

@@ -0,0 +1,78 @@
+import 'package:drift/native.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:kooltap/database/app_database.dart';
+
+/// The parts of the v12 schema that the v13 migration touches.
+const _v12Schema = [
+  'CREATE TABLE bar_tabs (id TEXT NOT NULL, customer_name TEXT NOT NULL, '
+      "status TEXT NOT NULL DEFAULT 'open', opened_at INTEGER NOT NULL, "
+      'closed_at INTEGER NULL, version INTEGER NOT NULL DEFAULT 0, '
+      'PRIMARY KEY (id))',
+  'CREATE TABLE tab_items (id TEXT NOT NULL, tab_id TEXT NOT NULL, '
+      'product_id TEXT NOT NULL, product_name TEXT NOT NULL, '
+      'quantity INTEGER NOT NULL, unit_price_in_cents INTEGER NOT NULL, '
+      'created_at INTEGER NOT NULL, PRIMARY KEY (id))',
+  'CREATE TABLE tab_item_purchases (id TEXT NOT NULL, '
+      'tab_item_id TEXT NOT NULL, purchased_at INTEGER NOT NULL, '
+      'removed_at INTEGER NULL, PRIMARY KEY (id))',
+  "INSERT INTO bar_tabs VALUES ('tab-1', 'Alice', 'open', 1700000000, NULL, 4)",
+  "INSERT INTO tab_items VALUES ('item-1', 'tab-1', 'prod-1', 'Beer', 3, 400, "
+      '1700000100)',
+  "INSERT INTO tab_item_purchases VALUES ('p-1', 'item-1', 1700000200, NULL)",
+  "INSERT INTO tab_item_purchases VALUES ('p-2', 'item-1', 1700000300, "
+      '1700000400)',
+  "INSERT INTO tab_item_purchases VALUES ('orphan', 'gone', 1700000500, NULL)",
+  'PRAGMA user_version = 12',
+];
+
+void main() {
+  late AppDatabase database;
+
+  setUp(() {
+    database = AppDatabase(
+      NativeDatabase.memory(
+        setup: (rawDatabase) {
+          for (final statement in _v12Schema) {
+            rawDatabase.execute(statement);
+          }
+        },
+      ),
+    );
+  });
+
+  tearDown(() async {
+    await database.close();
+  });
+
+  test('drops the unused status columns and keeps the tab', () async {
+    final tabs = await database.select(database.barTabs).get();
+
+    expect(tabs.single.customerName, 'Alice');
+    expect(tabs.single.version, 4);
+
+    final columns = await database
+        .customSelect('PRAGMA table_info(bar_tabs)')
+        .map((row) => row.read<String>('name'))
+        .get();
+    expect(columns, isNot(contains('status')));
+    expect(columns, isNot(contains('closed_at')));
+  });
+
+  test('backfills missing purchases up to the item quantity', () async {
+    final purchases = await (database.select(
+      database.tabItemPurchases,
+    )..where((row) => row.tabItemId.equals('item-1'))).get();
+
+    final active = purchases.where((row) => row.removedAt == null);
+    expect(active, hasLength(3));
+    expect(purchases.where((row) => row.removedAt != null), hasLength(1));
+  });
+
+  test('deletes purchases whose item no longer exists', () async {
+    final orphan = await (database.select(
+      database.tabItemPurchases,
+    )..where((row) => row.id.equals('orphan'))).getSingleOrNull();
+
+    expect(orphan, isNull);
+  });
+}