Add the rabbitmq module

rabbitmq/src/test/java/com/ankurm/rabbit/MaxLengthTest.java

@@ -0,0 +1,73 @@
+package com.ankurm.rabbit;
+
+import com.rabbitmq.client.GetResponse;
+import org.junit.jupiter.api.Test;
+import org.springframework.amqp.core.Binding;
+import org.springframework.amqp.core.BindingBuilder;
+import org.springframework.amqp.core.DirectExchange;
+import org.springframework.amqp.core.Queue;
+import org.springframework.amqp.core.QueueBuilder;
+import org.springframework.amqp.rabbit.core.RabbitAdmin;
+import org.springframework.amqp.rabbit.core.RabbitTemplate;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import java.util.List;
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * The third dead-letter trigger: a queue that is full.
+ *
+ * <p>Included because the article states all three triggers in one table, and this was the only
+ * row not produced by a run. It is now.
+ *
+ * @see <a href="../../../../../docs/04-dead-lettering.md">docs/04-dead-lettering.md</a>
+ */
+@SpringBootTest
+class MaxLengthTest {
+
+	static final String Q_BOUNDED = "orders.bounded";
+
+	@Autowired
+	RabbitTemplate template;
+
+	@Autowired
+	RabbitAdmin admin;
+
+	@Test
+	@SuppressWarnings("unchecked")
+	void exceedingMaxLengthDeadLettersTheOldestWithReasonMaxlen() throws Exception {
+		this.admin.deleteQueue(Q_BOUNDED);
+		Queue bounded = QueueBuilder.durable(Q_BOUNDED)
+				.maxLength(2)
+				.deadLetterExchange(Topology.DLX)
+				.deadLetterRoutingKey("failed")
+				.build();
+		this.admin.declareQueue(bounded);
+		Binding binding = BindingBuilder.bind(bounded)
+				.to(new DirectExchange(Topology.DIRECT)).with("bounded");
+		this.admin.declareBinding(binding);
+		this.admin.purgeQueue(Topology.Q_DLQ, false);
+
+		// Three messages into a queue that holds two. RabbitMQ drops from the HEAD, so the
+		// FIRST message is the one dead-lettered - the oldest, not the newest.
+		for (String id : List.of("m-1", "m-2", "m-3")) {
+			this.template.convertAndSend(Topology.DIRECT, "bounded", OrderMessage.of(id));
+		}
+
+		var message = this.template.receive(Topology.Q_DLQ, 10_000);
+		assertThat(message).isNotNull();
+		List<Map<String, Object>> deaths =
+				(List<Map<String, Object>>) message.getMessageProperties().getHeader("x-death");
+		System.out.println("=== x-death after x-max-length overflow ===");
+		deaths.get(0).forEach((k, v) -> System.out.printf("  %-16s %s%n", k, v));
+		System.out.println("  body            " + new String(message.getBody()));
+
+		assertThat(deaths.get(0)).containsEntry("reason", "maxlen");
+		assertThat(deaths.get(0)).containsEntry("queue", Q_BOUNDED);
+		assertThat(new String(message.getBody())).contains("m-1");
+	}
+
+}