Bookstore Test Infrastructure

Add test infrastructure to an existing Spring Boot bookstore application. The app uses PostgreSQL in production and has:

• BookController with GET /api/books and POST /api/books
• BookService for business logic
• BookRepository extends JpaRepository<Book, Long>
• Book entity with fields: id, title, author, isbn, price

The project currently has no tests. Set up the test infrastructure and write sample tests for each layer.

Output

Produce:

1. src/test/resources/application-test.yml -- test database configuration
2. src/test/java/com/example/bookstore/controller/BookControllerTest.java -- controller slice test
3. src/test/java/com/example/bookstore/repository/BookRepositoryTest.java -- repository slice test
4. src/test/java/com/example/bookstore/BookstoreIntegrationTest.java -- integration test

Each test file should contain at least 2 test methods. Do not produce the application source code.