Testing Patterns

Spock Framework

Version: Spock 2.4-M7 with Groovy 5.0.0-alpha-11 (Java 25 compatible)

Spock is a testing framework for Java and Groovy applications that combines:

• BDD-style Given-When-Then syntax
• Built-in mocking with Mock() and Stub()
• Expressive assertions and data-driven tests
• Integration with Spring Boot

Test Structure

Backend Tests (27 tests)

• ProductCommandServiceSpec (7 tests): Product creation, update, deletion, stock management
• ProductQueryServiceSpec (7 tests): Product queries and searches
• OrderCommandServiceSpec (5 tests): Order creation and processing
• OrderQueryServiceSpec (7 tests): Order queries by ID, customer, status
• ApplicationSpec (1 test): Application context test

Frontend Tests (12 tests)

• ProductServiceSpec (6 tests): REST client product operations
• OrderServiceSpec (3 tests): REST client order queries
• PurchaseOrderProducerSpec (2 tests): Kafka message publishing
• ApplicationSpec (1 test): Application context test

Example: ProductCommandServiceSpec

class ProductCommandServiceSpec extends Specification {
    ProductRepository productRepository = Mock()
    ProductCommandService service = new ProductCommandService(productRepository)

    def "should create product with valid data"() {
        given: "a valid product DTO"
        def productDTO = new ProductDTO(
            name: "Laptop",
            price: 999.99,
            stock: 10
        )

        when: "creating the product"
        service.createProduct(productDTO)

        then: "repository save is called once"
        1 * productRepository.save(_) >> { Product product ->
            assert product.name == "Laptop"
            assert product.price == 999.99
            product
        }
    }
}

Example: PurchaseOrderProducerSpec

class PurchaseOrderProducerSpec extends Specification {
    KafkaTemplate kafkaTemplate = Mock()
    PurchaseOrderProducer producer = new PurchaseOrderProducer(kafkaTemplate)

    def "should send order to correct Kafka topic"() {
        given: "a purchase order"
        def order = new PurchaseOrderDTO(
            orderId: "ORDER-123",
            total: 100.0
        )

        when: "sending the order"
        producer.sendOrder(order)

        then: "kafka template sends to purchase-orders topic"
        1 * kafkaTemplate.send("purchase-orders", "ORDER-123", order)
    }
}

Running Tests

# Run all tests
mvn test

# Run backend tests only
cd spring-boot-kafka-backend && mvn test

# Run frontend tests only
cd spring-boot-kafka-frontend && mvn test

# Run specific test class
mvn test -Dtest=ProductCommandServiceSpec

Java 25 Compatibility

The project uses Groovy 5.0.0-alpha-11, which supports Java 25 bytecode (major version 69). Earlier versions of Groovy do not support Java 25.

Maven Configuration:

<plugin>
    <groupId>org.codehaus.gmavenplus</groupId>
    <artifactId>gmavenplus-plugin</artifactId>
    <version>4.0.1</version>
    <configuration>
        <skipBytecodeCheck>true</skipBytecodeCheck>
    </configuration>
</plugin>