Polish "Add auto-configuration for RabbitMQ metrics"

Closes gh-10887

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/amqp/RabbitMetrics.java

@@ -24,30 +24,42 @@ import io.micrometer.core.instrument.MeterRegistry;
 import io.micrometer.core.instrument.Tag;
 import io.micrometer.core.instrument.binder.MeterBinder;
 
+import org.springframework.util.Assert;
+
 /**
  * A {@link MeterBinder} for RabbitMQ Java Client metrics.
  *
  * @author Arnaud Cogoluègnes
+ * @author Stephane Nicoll
  * @since 2.0.0
  */
 public class RabbitMetrics implements MeterBinder {
 
 	private final Iterable<Tag> tags;
 
+	private final String name;
+
 	private final ConnectionFactory connectionFactory;
 
-	public RabbitMetrics(ConnectionFactory connectionFactory) {
-		this(connectionFactory, Collections.emptyList());
-	}
-
-	public RabbitMetrics(ConnectionFactory connectionFactory, Iterable<Tag> tags) {
+	/**
+	 * Create a new meter binder recording  the specified {@link ConnectionFactory}.
+	 * @param connectionFactory the {@link ConnectionFactory} to instrument
+	 * @param name the name prefix of the metrics
+	 * @param tags tags to apply to all recorded metrics
+	 */
+	public RabbitMetrics(ConnectionFactory connectionFactory, String name,
+			Iterable<Tag> tags) {
+		Assert.notNull(connectionFactory, "ConnectionFactory must not be null");
+		Assert.notNull(name, "Name must not be null");
 		this.connectionFactory = connectionFactory;
-		this.tags = tags;
+		this.name = name;
+		this.tags = (tags  != null ?  tags : Collections.EMPTY_LIST);
 	}
 
 	@Override
 	public void bindTo(MeterRegistry registry) {
-		this.connectionFactory.setMetricsCollector(new MicrometerMetricsCollector(registry, "rabbitmq", this.tags));
+		this.connectionFactory.setMetricsCollector(new MicrometerMetricsCollector(
+				registry, this.name, this.tags));
 	}
 
 }

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/amqp/RabbitMetricsTests.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2012-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.actuate.metrics.amqp;
+
+import com.rabbitmq.client.ConnectionFactory;
+import io.micrometer.core.instrument.Tags;
+import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Tests for {@link RabbitMetrics}.
+ *
+ * @author Stephane Nicoll
+ */
+public class RabbitMetricsTests {
+
+	@Test
+	public void connectionFactoryIsInstrumented() {
+		ConnectionFactory connectionFactory = mockConnectionFactory();
+		SimpleMeterRegistry registry = new SimpleMeterRegistry();
+		new RabbitMetrics(connectionFactory, "rabbit", null).bindTo(registry);
+		assertThat(registry.find("rabbit.connections").meter()).isPresent();
+	}
+
+	@Test
+	public void connectionFactoryWithTagsIsInstrumented() {
+		ConnectionFactory connectionFactory = mockConnectionFactory();
+		SimpleMeterRegistry registry = new SimpleMeterRegistry();
+		new RabbitMetrics(connectionFactory, "test", Tags.zip("env", "prod"))
+				.bindTo(registry);
+		assertThat(registry.find("test.connections")
+				.tags("env", "prod").meter()).isPresent();
+		assertThat(registry.find("test.connections")
+				.tags("env", "dev").meter()).isNotPresent();
+	}
+
+	private ConnectionFactory mockConnectionFactory() {
+		return mock(ConnectionFactory.class);
+	}
+
+}