Fix race condition in DebeziumMessProducerTests

The `then(debeziumEngineMock).should().run()` cannot be just checked
after `debeziumMessageProducer.start()`: the `DebeziumEngine` is really
started on a separate thread.

* Check for a `run()` interaction with the mock already after calling
`debeziumMessageProducer.stop()`.
The `stop()` waits for an internal `latch` which is fulfilled when
`DebeziumEngine` exists from its `run()` cycle
* Rename `DebeziumMessageProducer.latch` to `lifecycleLatch` to give it
more sense.

Author: artembilan

spring-integration-debezium/src/main/java/org/springframework/integration/debezium/inbound/DebeziumMessageProducer.java

@@ -77,7 +77,7 @@ public class DebeziumMessageProducer extends MessageProducerSupport {
 
 	private ThreadFactory threadFactory;
 
-	private volatile CountDownLatch latch = new CountDownLatch(0);
+	private volatile CountDownLatch lifecycleLatch = new CountDownLatch(0);
 
 	/**
 	 * Create new Debezium message producer inbound channel adapter.
@@ -174,10 +174,10 @@ protected void onInit() {
 
 	@Override
 	protected void doStart() {
-		if (this.latch.getCount() > 0) {
+		if (this.lifecycleLatch.getCount() > 0) {
 			return;
 		}
-		this.latch = new CountDownLatch(1);
+		this.lifecycleLatch = new CountDownLatch(1);
 		this.executorService.execute(() -> {
 			try {
 				// Runs the debezium connector and deliver database changes to the registered consumer. This method
@@ -191,7 +191,7 @@ protected void doStart() {
 				this.debeziumEngine.run();
 			}
 			finally {
-				this.latch.countDown();
+				this.lifecycleLatch.countDown();
 			}
 		});
 	}
@@ -205,7 +205,7 @@ protected void doStop() {
 			logger.warn(e, "Debezium failed to close!");
 		}
 		try {
-			if (!this.latch.await(5, TimeUnit.SECONDS)) {
+			if (!this.lifecycleLatch.await(5, TimeUnit.SECONDS)) {
 				throw new IllegalStateException("Failed to stop " + this);
 			}
 		}

spring-integration-debezium/src/test/java/org/springframework/integration/debezium/inbound/DebeziumMessageProducerTests.java

@@ -38,6 +38,7 @@
 
 /**
  * @author Christian Tzolov
+ * @author Artem Bilan
  *
  * @since 6.2
  */
@@ -76,12 +77,15 @@ public void testDebeziumMessageProducerLifecycle() throws IOException {
 
 		await().atMost(5, TimeUnit.SECONDS).until(() -> debeziumMessageProducer.isRunning());
 		assertThat(debeziumMessageProducer.isActive()).isEqualTo(true);
-		then(debeziumEngineMock).should().run();
 
 		debeziumMessageProducer.stop(); // STOP
 
 		assertThat(debeziumMessageProducer.isActive()).isEqualTo(false);
 		assertThat(debeziumMessageProducer.isRunning()).isEqualTo(false);
+
+		// The DebeziumEngine is started on a different thread.
+		// Only the way to catch the run() mock is to stop DebeziumMessageProducer and wait for its internal latch
+		then(debeziumEngineMock).should().run();
 		then(debeziumEngineMock).should().close();
 
 		reset(debeziumEngineMock);
@@ -90,10 +94,10 @@ public void testDebeziumMessageProducerLifecycle() throws IOException {
 
 		await().atMost(5, TimeUnit.SECONDS).until(() -> debeziumMessageProducer.isRunning());
 		assertThat(debeziumMessageProducer.isActive()).isEqualTo(true);
-		then(debeziumEngineMock).should().run();
 
 		debeziumMessageProducer.destroy(); // DESTROY
 
+		then(debeziumEngineMock).should().run();
 		then(debeziumEngineMock).should().close();
 	}