Add more docs in the migrations example

extras/migrations_example/README.md

@@ -0,0 +1,23 @@
+Example to demonstrate tests for schema migrations.
+
+See `test/migration_test.dart` on how to use the generated verification code.
+
+## Workflow
+
+### Schema changes
+
+After adapting a schema and incrementing the `schemaVersion` in the database, run
+
+```
+dart pub run moor_generator schema dump lib/database.dart moor_migrations/moor_schema_v2.json
+```
+
+Replace `_v2` with the current `schemaVersion`.
+
+### Generating test code
+
+Run
+
+```
+dart pub run moor_generator schema generate moor_migrations/ test/generated/
+```

extras/migrations_example/lib/database.dart

@@ -20,7 +20,12 @@ class Database extends _$Database {
   MigrationStrategy get migration {
     return MigrationStrategy(
       onUpgrade: (m, before, now) async {
-        await m.addColumn(users, users.name);
+        for (var target = before + 1; target <= now; target++) {
+          if (target == 2) {
+            // Migration from 1 to 2: Add name column in users
+            await m.addColumn(users, users.name);
+          }
+        }
       },
     );
   }

extras/migrations_example/pubspec.yaml

@@ -1,4 +1,5 @@
 name: migrations_example
+publish_to: none
 version: 1.0.0
 
 environment:

extras/migrations_example/test/migration_test.dart

@@ -2,6 +2,7 @@ import 'package:migrations_example/database.dart';
 import 'package:test/test.dart';
 import 'package:moor_generator/api/migrations.dart';
 
+// Import the generated schema helper to instantiate databases at old versions.
 import 'generated/schema.dart';
 
 void main() {