Added tests and fix docs for AsyncRestTemplate

fixes #334

docs/src/main/asciidoc/spring-cloud-sleuth.adoc

@@ -456,7 +456,12 @@ If you create a `RestTemplate` instance with a `new` keyword then the instrument
 
 Custom instrumentation is set to create and close Spans upon sending and receiving requests. You can customize the `ClientHttpRequestFactory`
 and the `AsyncClientHttpRequestFactory` by registering your beans. Remember to use tracing compatible implementations (e.g. don't forget to
-wrap `ThreadPoolTaskScheduler` in a `TraceAsyncListenableTaskExecutor`).
+wrap `ThreadPoolTaskScheduler` in a `TraceAsyncListenableTaskExecutor`). Example of custom request factories:
+
+[source,java]
+----
+include::../../../../spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/client/TraceWebAsyncClientAutoConfigurationTest.java[tags=async_template_factories,indent=0]
+----
 
 To block the `AsyncRestTemplate` features set `spring.sleuth.web.async.client.enabled` to `false`.
 To disable creation of the default `TraceAsyncClientHttpRequestFactoryWrapper` set `spring.sleuth.web.async.client.factory.enabled`

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/client/TraceAsyncClientHttpRequestFactoryWrapper.java

@@ -43,8 +43,8 @@ import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
 public class TraceAsyncClientHttpRequestFactoryWrapper extends AbstractTraceHttpRequestInterceptor
 		implements ClientHttpRequestFactory, AsyncClientHttpRequestFactory {
 
-	private final AsyncClientHttpRequestFactory asyncDelegate;
-	private final ClientHttpRequestFactory syncDelegate;
+	final AsyncClientHttpRequestFactory asyncDelegate;
+	final ClientHttpRequestFactory syncDelegate;
 
 	/**
 	 * According to the JavaDocs all Spring {@link AsyncClientHttpRequestFactory} implement

spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/client/TraceWebAsyncClientAutoConfigurationTest.java

@@ -0,0 +1,92 @@
+/*
+ * Copyright 2013-2016 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.sleuth.instrument.web.client;
+
+import java.io.IOException;
+import java.net.URI;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.client.AsyncClientHttpRequest;
+import org.springframework.http.client.AsyncClientHttpRequestFactory;
+import org.springframework.http.client.ClientHttpRequest;
+import org.springframework.http.client.ClientHttpRequestFactory;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.web.client.AsyncRestTemplate;
+
+import static org.assertj.core.api.BDDAssertions.then;
+import static org.springframework.boot.test.context.SpringBootTest.WebEnvironment.RANDOM_PORT;
+
+/**
+ * @author Marcin Grzejszczak
+ */
+@RunWith(SpringJUnit4ClassRunner.class)
+@SpringBootTest(classes = {
+		TraceWebAsyncClientAutoConfigurationTest.TestConfiguration.class }, webEnvironment = RANDOM_PORT)
+public class TraceWebAsyncClientAutoConfigurationTest {
+
+	@Autowired AsyncRestTemplate asyncRestTemplate;
+	@Autowired MySyncClientHttpRequestFactory mySyncClientHttpRequestFactory;
+	@Autowired MyAsyncClientHttpRequestFactory myAsyncClientHttpRequestFactory;
+
+	@Test
+	public void should_inject_to_async_rest_template_custom_client_http_request_factory() {
+		then(this.asyncRestTemplate.getAsyncRequestFactory()).isInstanceOf(TraceAsyncClientHttpRequestFactoryWrapper.class);
+		TraceAsyncClientHttpRequestFactoryWrapper wrapper = (TraceAsyncClientHttpRequestFactoryWrapper) this.asyncRestTemplate.getAsyncRequestFactory();
+		then(wrapper.syncDelegate).isSameAs(this.mySyncClientHttpRequestFactory);
+		then(wrapper.asyncDelegate).isSameAs(this.myAsyncClientHttpRequestFactory);
+		then(this.asyncRestTemplate).isInstanceOf(TraceAsyncRestTemplate.class);
+	}
+
+	// tag::async_template_factories[]
+	@EnableAutoConfiguration
+	@Configuration
+	public static class TestConfiguration {
+
+		@Bean
+		ClientHttpRequestFactory mySyncClientFactory() {
+			return new MySyncClientHttpRequestFactory();
+		}
+
+		@Bean
+		AsyncClientHttpRequestFactory myAsyncClientFactory() {
+			return new MyAsyncClientHttpRequestFactory();
+		}
+	}
+	// end::async_template_factories[]
+
+	private static class MySyncClientHttpRequestFactory implements ClientHttpRequestFactory {
+		@Override public ClientHttpRequest createRequest(URI uri, HttpMethod httpMethod)
+				throws IOException {
+			return null;
+		}
+	}
+	private static class MyAsyncClientHttpRequestFactory implements AsyncClientHttpRequestFactory {
+		@Override
+		public AsyncClientHttpRequest createAsyncRequest(URI uri, HttpMethod httpMethod)
+				throws IOException {
+			return null;
+		}
+	}
+
+}

spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/client/WebClientDiscoveryExceptionTests.java

@@ -26,8 +26,7 @@ import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
-import org.springframework.boot.test.SpringApplicationConfiguration;
-import org.springframework.boot.test.WebIntegrationTest;
+import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
 import org.springframework.cloud.client.loadbalancer.LoadBalanced;
 import org.springframework.cloud.netflix.feign.EnableFeignClients;
@@ -44,6 +43,7 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.http.ResponseEntity;
 import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.context.TestPropertySource;
 import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
@@ -51,12 +51,12 @@ import org.springframework.web.client.RestTemplate;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.BDDAssertions.then;
+import static org.springframework.boot.test.context.SpringBootTest.WebEnvironment.RANDOM_PORT;
 
 @RunWith(SpringJUnit4ClassRunner.class)
-@SpringApplicationConfiguration(classes = {
-		WebClientDiscoveryExceptionTests.TestConfiguration.class })
-@WebIntegrationTest(value = {
-		"spring.application.name=exceptionservice" }, randomPort = true)
+@SpringBootTest(classes = {
+		WebClientDiscoveryExceptionTests.TestConfiguration.class }, webEnvironment = RANDOM_PORT)
+@TestPropertySource(properties = "spring.application.name=exceptionservice")
 @DirtiesContext
 public class WebClientDiscoveryExceptionTests {