Add BAEL-2067 DomainEvents examples

spring-data-jpa/src/test/java/com/baeldung/ddd/event/Aggregate2EventsIntegrationTest.java

@@ -0,0 +1,68 @@
+/**
+ *
+ */
+package com.baeldung.ddd.event;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.mock.mockito.MockBean;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+
+@SpringJUnitConfig
+@SpringBootTest
+class Aggregate2EventsIntegrationTest {
+    @MockBean
+    private TestEventHandler eventHandler;
+    @Autowired
+    private Aggregate2Repository repository;
+
+    // @formatter:off
+    @DisplayName("given aggregate with @AfterDomainEventPublication,"
+        + " when do domain operation and save twice,"
+        + " then an event is published only for the first time")
+    // @formatter:on
+    @Test
+    void afterDomainEvents() {
+        // given
+        Aggregate2 aggregate = new Aggregate2();
+
+        // when
+        aggregate.domainOperation();
+        repository.save(aggregate);
+        repository.save(aggregate);
+
+        // then
+        verify(eventHandler, times(1)).handleEvent(any(DomainEvent.class));
+    }
+
+    @BeforeEach
+    void beforeEach() {
+        repository.deleteAll();
+    }
+
+    // @formatter:off
+    @DisplayName("given aggregate with @DomainEvents,"
+        + " when do domain operation and save,"
+        + " then an event is published")
+    // @formatter:on
+    @Test
+    void domainEvents() {
+        // given
+        Aggregate2 aggregate = new Aggregate2();
+
+        // when
+        aggregate.domainOperation();
+        repository.save(aggregate);
+
+        // then
+        verify(eventHandler, times(1)).handleEvent(any(DomainEvent.class));
+    }
+
+}

spring-data-jpa/src/test/java/com/baeldung/ddd/event/Aggregate3EventsIntegrationTest.java

@@ -0,0 +1,63 @@
+/**
+ *
+ */
+package com.baeldung.ddd.event;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.mock.mockito.MockBean;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+
+@SpringJUnitConfig
+@SpringBootTest
+class Aggregate3EventsIntegrationTest {
+
+    @MockBean
+    private TestEventHandler eventHandler;
+    @Autowired
+    private Aggregate3Repository repository;
+
+    // @formatter:off
+    @DisplayName("given aggregate extending AbstractAggregateRoot,"
+        + " when do domain operation and save twice,"
+        + " then an event is published only for the first time")
+    // @formatter:on
+    @Test
+    void afterDomainEvents() {
+        // given
+        Aggregate3 aggregate = new Aggregate3();
+
+        // when
+        aggregate.domainOperation();
+        repository.save(aggregate);
+        repository.save(aggregate);
+
+        // then
+        verify(eventHandler, times(1)).handleEvent(any(DomainEvent.class));
+    }
+
+    // @formatter:off
+    @DisplayName("given aggregate extending AbstractAggregateRoot,"
+        + " when do domain operation and save,"
+        + " then an event is published")
+    // @formatter:on
+    @Test
+    void domainEvents() {
+        // given
+        Aggregate3 aggregate = new Aggregate3();
+
+        // when
+        aggregate.domainOperation();
+        repository.save(aggregate);
+
+        // then
+        verify(eventHandler, times(1)).handleEvent(any(DomainEvent.class));
+    }
+
+}

spring-data-jpa/src/test/java/com/baeldung/ddd/event/AggregateEventsIntegrationTest.java

@@ -0,0 +1,82 @@
+package com.baeldung.ddd.event;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyZeroInteractions;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.context.TestConfiguration;
+import org.springframework.boot.test.mock.mockito.MockBean;
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.context.annotation.Bean;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+
+@SpringJUnitConfig
+@SpringBootTest
+class AggregateEventsIntegrationTest {
+
+    @Autowired
+    private DomainService domainService;
+
+    @MockBean
+    private TestEventHandler eventHandler;
+    @Autowired
+    private ApplicationEventPublisher eventPublisher;
+    @Autowired
+    private AggregateRepository repository;
+
+    // @formatter:off
+    @DisplayName("given existing aggregate,"
+        + " when do domain operation directly on aggregate,"
+        + " then domain event is NOT published")
+    // @formatter:on
+    @Test
+    void aggregateEventsTest() {
+        Aggregate existingDomainEntity = new Aggregate(0, eventPublisher);
+        repository.save(existingDomainEntity);
+
+        // when
+        repository.findById(existingDomainEntity.getId())
+            .get()
+            .domainOperation();
+
+        // then
+        verifyZeroInteractions(eventHandler);
+    }
+
+    @BeforeEach
+    void beforeEach() {
+        repository.deleteAll();
+    }
+
+    // @formatter:off
+    @DisplayName("given existing aggregate,"
+        + " when do domain operation on service,"
+        + " then domain event is published")
+    // @formatter:on
+    @Test
+    void serviceEventsTest() {
+        Aggregate existingDomainEntity = new Aggregate(1, eventPublisher);
+        repository.save(existingDomainEntity);
+
+        // when
+        domainService.serviceDomainOperation(existingDomainEntity.getId());
+
+        // then
+        verify(eventHandler, times(1)).handleEvent(any(DomainEvent.class));
+    }
+
+    @TestConfiguration
+    public static class TestConfig {
+        @Bean
+        public DomainService domainService(AggregateRepository repository, ApplicationEventPublisher eventPublisher) {
+            return new DomainService(repository, eventPublisher);
+        }
+    }
+
+}

spring-data-jpa/src/test/java/com/baeldung/ddd/event/TestEventHandler.java

@@ -0,0 +1,12 @@
+/**
+ *
+ */
+package com.baeldung.ddd.event;
+
+import org.springframework.transaction.event.TransactionalEventListener;
+
+interface TestEventHandler {
+    @TransactionalEventListener
+    void handleEvent(DomainEvent event);
+
+}