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 +1,105 @@
+/*
+ * 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.After;
+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.cloud.sleuth.trace.TestSpanContextHolder;
+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.annotation.DirtiesContext;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.web.client.AsyncRestTemplate;
+
+import com.netflix.hystrix.strategy.HystrixPlugins;
+
+import static org.assertj.core.api.BDDAssertions.then;
+
+/**
+ * @author Marcin Grzejszczak
+ */
+@RunWith(SpringJUnit4ClassRunner.class)
+@SpringApplicationConfiguration(classes = {
+		TraceWebAsyncClientAutoConfigurationTest.TestConfiguration.class })
+@WebIntegrationTest(randomPort = true)
+@DirtiesContext
+public class TraceWebAsyncClientAutoConfigurationTest {
+
+	@Autowired AsyncRestTemplate asyncRestTemplate;
+	@Autowired MySyncClientHttpRequestFactory mySyncClientHttpRequestFactory;
+	@Autowired MyAsyncClientHttpRequestFactory myAsyncClientHttpRequestFactory;
+
+	@After
+	public void close() {
+		TestSpanContextHolder.removeCurrentSpan();
+		HystrixPlugins.reset();
+	}
+
+	@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/WebClientTests.java

@@ -25,8 +25,10 @@ import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Random;
+import java.util.concurrent.TimeUnit;
 import java.util.stream.Collectors;
 
+import com.jayway.awaitility.Awaitility;
 import com.netflix.loadbalancer.BaseLoadBalancer;
 import com.netflix.loadbalancer.ILoadBalancer;
 import com.netflix.loadbalancer.Server;
@@ -113,13 +115,19 @@ public class WebClientTests {
 		then(getHeader(response, Span.TRACE_ID_NAME)).isNotNull();
 		then(getHeader(response, Span.SPAN_ID_NAME)).isNotNull();
 		then(this.listener.getSpans()).isNotEmpty();
-		Optional<Span> noTraceSpan = this.listener.getSpans().stream().filter(span ->
-				"http:/notrace".equals(span.getName()) && !span.tags().isEmpty()).findFirst();
-		then(noTraceSpan.isPresent()).isTrue();
-		// TODO: matches cause there is an issue with Feign not providing the full URL at the interceptor level
-		then(noTraceSpan.get()).matchesATag("http.url", ".*/notrace")
-				.hasATag("http.path", "/notrace")
-				.hasATag("http.method", "GET");
+		Awaitility.await().atMost(3, TimeUnit.SECONDS).until(() -> {
+			log.info("Seraching for a notrace span in " + this.listener.getSpans());
+			Optional<Span> noTraceSpan = this.listener.getSpans().stream().filter(span ->
+					"http:/notrace".equals(span.getName()) && !span.tags().isEmpty()).findFirst();
+			then(noTraceSpan.isPresent()).isTrue();
+			log.info("No trace span found");
+			// TODO: matches cause there is an issue with Feign not providing the full URL at the interceptor level
+			then(noTraceSpan.get()).matchesATag("http.url", ".*/notrace")
+					.hasATag("http.path", "/notrace")
+					.hasATag("http.method", "GET");
+			log.info("Notrace has all the necessary tags");
+		});
+
 	}
 
 	Object[] parametersForShouldCreateANewSpanWithClientSideTagsWhenNoPreviousTracingWasPresent() {