database test: Rewrite database tests using generated helpers

The tests are adapted from the test template generated from
`dart run drift_dev make-migrations`.

This saves us from writing the simple migration tests between schemas
without data in the future. For the test that upgrade the schema with
data, with the helper, while it ended up having more lines than the
original, the test becomes more structured this way.

Signed-off-by: Zixuan James Li <zixuan@zulip.com>

Author: PIG208

test/model/database_test.dart

@@ -105,39 +105,56 @@ void main() {
       await db.close();
     }, skip: true); // TODO(#1172): unskip this
 
-    test('upgrade to v2, empty', () async {
-      final connection = await verifier.startAt(1);
-      final db = AppDatabase(connection);
-      await verifier.migrateAndValidate(db, 2);
-      await db.close();
+    group('migrate without data', () {
+      // These simple tests verify all possible schema updates with a simple (no
+      // data) migration. This is a quick way to ensure that written database
+      // migrations properly alter the schema.
+      const versions = GeneratedHelper.versions;
+      for (final (i, fromVersion) in versions.indexed) {
+        group('from $fromVersion', () {
+          for (final toVersion in versions.skip(i + 1)) {
+            test('to $toVersion', () async {
+              final schema = await verifier.schemaAt(fromVersion);
+              final db = AppDatabase(schema.newConnection());
+              await verifier.migrateAndValidate(db, toVersion);
+              await db.close();
+            });
+          }
+        });
+      }
     });
 
-    test('upgrade to v2, with data', () async {
-      final schema = await verifier.schemaAt(1);
-      final before = v1.DatabaseAtV1(schema.newConnection());
-      await before.into(before.accounts).insert(v1.AccountsCompanion.insert(
-        realmUrl: 'https://chat.example/',
-        userId: 1,
-        email: 'asdf@example.org',
-        apiKey: '1234',
-        zulipVersion: '6.0',
-        zulipMergeBase: const Value('6.0'),
-        zulipFeatureLevel: 42,
-      ));
-      final accountV1 = await before.select(before.accounts).watchSingle().first;
-      await before.close();
-
-      final db = AppDatabase(schema.newConnection());
-      await verifier.migrateAndValidate(db, 2);
-      await db.close();
-
-      final after = v2.DatabaseAtV2(schema.newConnection());
-      final account = await after.select(after.accounts).getSingle();
-      check(account.toJson()).deepEquals({
-        ...accountV1.toJson(),
-        'ackedPushToken': null,
+    // Testing this can be useful for migrations that change existing columns
+    // (e.g. by alterating their type or constraints). Migrations that only add
+    // tables or columns typically don't need these advanced tests. For more
+    // information, see https://drift.simonbinder.eu/migrations/tests/#verifying-data-integrity
+    group('migrate with data', () {
+      test('upgrade to v2', () async {
+        late final v1.AccountsData oldAccountData;
+        await verifier.testWithDataIntegrity(
+          oldVersion: 1, createOld: v1.DatabaseAtV1.new,
+          newVersion: 2, createNew: v2.DatabaseAtV2.new,
+          openTestedDatabase: AppDatabase.new,
+          createItems: (batch, oldDb) async {
+            await oldDb.into(oldDb.accounts).insert(v1.AccountsCompanion.insert(
+              realmUrl: 'https://chat.example/',
+              userId: 1,
+              email: 'asdf@example.org',
+              apiKey: '1234',
+              zulipVersion: '6.0',
+              zulipMergeBase: const Value('6.0'),
+              zulipFeatureLevel: 42,
+            ));
+            oldAccountData = await oldDb.select(oldDb.accounts).watchSingle().first;
+          },
+          validateItems: (newDb) async {
+            final account = await newDb.select(newDb.accounts).getSingle();
+            check(account.toJson()).deepEquals({
+              ...oldAccountData.toJson(),
+              'ackedPushToken': null,
+            });
+          });
       });
-      await after.close();
     });
   });
 }