Update gateway actuator metrics test to use @ClassPathExclusions to verify gateway doesn't fall over when actuator metrics are not added as project dependency

spring-cloud-gateway-sample/pom.xml

@@ -24,12 +24,6 @@
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-actuator</artifactId>
-			<exclusions> <!-- exclude metrics to verify that gateway doesn't fall over when it is not available -->
-				<exclusion>
-					<groupId>io.micrometer</groupId>
-					<artifactId>micrometer-core</artifactId>
-				</exclusion>
-			</exclusions>
 		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
@@ -60,6 +54,11 @@
 			<artifactId>spring-boot-starter-test</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-test-support</artifactId>
+			<scope>test</scope>
+		</dependency>
 		<dependency>
 			<groupId>io.projectreactor</groupId>
 			<artifactId>reactor-test</artifactId>

spring-cloud-gateway-sample/src/main/java/org/springframework/cloud/gateway/sample/GatewaySampleApplication.java

@@ -45,6 +45,7 @@ import org.springframework.web.reactive.function.server.ServerResponse;
 @Import(AdditionalRoutes.class)
 public class GatewaySampleApplication {
 
+	public static final String HELLO_FROM_FAKE_ACTUATOR_METRICS_GATEWAY_REQUESTS = "hello from fake /actuator/metrics/gateway.requests";
 	@Value("${test.uri:http://httpbin.org:80}")
 	String uri;
 
@@ -135,6 +136,14 @@ public class GatewaySampleApplication {
 		return route;
 	}
 
+	@Bean
+	public RouterFunction<ServerResponse> testWhenMetricPathIsNotMeet() {
+		RouterFunction<ServerResponse> route = RouterFunctions.route(
+				RequestPredicates.path("/actuator/metrics/gateway.requests"),
+				request -> ServerResponse.ok().body(BodyInserters.fromObject(HELLO_FROM_FAKE_ACTUATOR_METRICS_GATEWAY_REQUESTS)));
+		return route;
+	}
+
 	static class Hello {
 		String message;
 

spring-cloud-gateway-sample/src/test/java/org/springframework/cloud/gateway/sample/GatewaySampleApplicationTests.java

@@ -17,9 +17,12 @@
 
 package org.springframework.cloud.gateway.sample;
 
+import java.io.IOException;
 import java.time.Duration;
 import java.util.Map;
 
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import com.netflix.loadbalancer.Server;
 import com.netflix.loadbalancer.ServerList;
 import org.junit.AfterClass;
@@ -43,6 +46,7 @@ import org.springframework.test.web.reactive.server.WebTestClient;
 import org.springframework.util.SocketUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertEquals;
 import static org.springframework.boot.test.context.SpringBootTest.WebEnvironment.RANDOM_PORT;
 
 /**
@@ -181,6 +185,27 @@ public class GatewaySampleApplicationTests {
 				.expectStatus().isOk();
 	}
 
+	@Test
+	public void actuatorMetrics() {
+		contextLoads();
+		webClient.get()
+				.uri("http://localhost:" + managementPort
+						+ "/actuator/metrics/gateway.requests")
+				.exchange().expectStatus().isOk().expectBody().consumeWith(i -> {
+					String body = new String(i.getResponseBodyContent());
+					ObjectMapper mapper = new ObjectMapper();
+					try {
+						JsonNode actualObj = mapper.readTree(body);
+						JsonNode findValue = actualObj.findValue("name");
+						assertEquals("Expected to find metric with name gateway.requests",
+								"gateway.requests", findValue.asText());
+					}
+					catch (IOException e) {
+						throw new IllegalStateException(e);
+					}
+				});
+	}
+
 	@Configuration
 	@EnableAutoConfiguration
 	@RibbonClient(name = "httpbin", configuration = RibbonConfig.class)

spring-cloud-gateway-sample/src/test/java/org/springframework/cloud/gateway/sample/GatewaySampleApplicationWithoutMetricsTests.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright 2013-2017 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.cloud.gateway.sample;
+
+import java.time.Duration;
+
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.boot.WebApplicationType;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.cloud.gateway.sample.GatewaySampleApplicationTests.TestConfig;
+import org.springframework.cloud.test.ClassPathExclusions;
+import org.springframework.cloud.test.ModifiedClassPathRunner;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.web.reactive.server.WebTestClient;
+import org.springframework.util.SocketUtils;
+
+@RunWith(ModifiedClassPathRunner.class)
+@ClassPathExclusions({ "micrometer-*.jar" })
+@DirtiesContext
+public class GatewaySampleApplicationWithoutMetricsTests {
+
+	static protected int port;
+
+	protected WebTestClient webClient;
+	protected String baseUri;
+
+	@BeforeClass
+	public static void beforeClass() {
+		port = SocketUtils.findAvailableTcpPort();
+		System.setProperty("server.port", Integer.toString(port));
+	}
+
+	@AfterClass
+	public static void afterClass() {
+		System.clearProperty("server.port");
+	}
+
+	@Before
+	public void setup() {
+		baseUri = "http://localhost:" + port;
+		this.webClient = WebTestClient.bindToServer()
+				.responseTimeout(Duration.ofSeconds(10)).baseUrl(baseUri).build();
+	}
+
+	protected ConfigurableApplicationContext init(Class<?> config) {
+		return new SpringApplicationBuilder().web(WebApplicationType.REACTIVE)
+				.sources(GatewaySampleApplication.class, config).run();
+	}
+
+	@Test
+	public void actuatorMetrics() {
+		init(TestConfig.class);
+		webClient.get().uri("/get").exchange().expectStatus().isOk();
+		webClient.get()
+				.uri("http://localhost:" + port + "/actuator/metrics/gateway.requests")
+				.exchange().expectStatus().isOk().expectBody(String.class).isEqualTo(
+						GatewaySampleApplication.HELLO_FROM_FAKE_ACTUATOR_METRICS_GATEWAY_REQUESTS);
+	}
+
+}