Protect against race condition where output file exists but it is empty

wilkinsona · wilkinsona · commit 160d609bd4fb · 2014-10-20T11:04:14.000+01:00
Previously, there was a timing window where the output file had been created but it was empty. This would cause the test to fail as the output was read from the empty file and didn’t match the expected “Hello World”. This commit updates the test to only process the resources in the output directory when all the resolved resources have a non-zero content length. An @before method has also been added to delete the output produced by the test so that the outcome of the test isn’t affected by files generated by previous runs. Fixes spring-projectsgh-1735
diff --git a/spring-boot-samples/spring-boot-sample-integration/src/test/java/sample/integration/consumer/SampleIntegrationApplicationTests.java b/spring-boot-samples/spring-boot-sample-integration/src/test/java/sample/integration/consumer/SampleIntegrationApplicationTests.java
@@ -16,19 +16,23 @@
 
 package sample.integration.consumer;
 
+import java.io.File;
+import java.io.IOException;
 import java.util.concurrent.Callable;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 
 import org.junit.AfterClass;
+import org.junit.Before;
 import org.junit.BeforeClass;
 import org.junit.Test;
 import org.springframework.boot.SpringApplication;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.core.io.DefaultResourceLoader;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.support.ResourcePatternUtils;
+import org.springframework.util.FileSystemUtils;
 import org.springframework.util.StreamUtils;
 
 import sample.integration.SampleIntegrationApplication;
@@ -40,6 +44,7 @@
  * Basic integration tests for service demo application.
  *
  * @author Dave Syer
+ * @author Andy Wilkinson
  */
 public class SampleIntegrationApplicationTests {
 
@@ -57,6 +62,11 @@ public static void stop() {
 		}
 	}
 
+	@Before
+	public void deleteOutput() {
+		FileSystemUtils.deleteRecursively(new File("target/output"));
+	}
+
 	@Test
 	public void testVanillaExchange() throws Exception {
 		SpringApplication.run(ProducerApplication.class, "World");
@@ -69,12 +79,10 @@ private String getOutput() throws Exception {
 				new Callable<String>() {
 					@Override
 					public String call() throws Exception {
-						Resource[] resources = new Resource[0];
+						Resource[] resources = getResourcesWithContent();
 						while (resources.length == 0) {
 							Thread.sleep(200);
-							resources = ResourcePatternUtils.getResourcePatternResolver(
-									new DefaultResourceLoader()).getResources(
-									"file:target/output/**");
+							resources = getResourcesWithContent();
 						}
 						StringBuilder builder = new StringBuilder();
 						for (Resource resource : resources) {
@@ -86,4 +94,15 @@ public String call() throws Exception {
 				});
 		return future.get(30, TimeUnit.SECONDS);
 	}
+
+	private Resource[] getResourcesWithContent() throws IOException {
+		Resource[] candidates = ResourcePatternUtils.getResourcePatternResolver(
+				new DefaultResourceLoader()).getResources("file:target/output/**");
+		for (Resource candidate : candidates) {
+			if (candidate.contentLength() == 0) {
+				return new Resource[0];
+			}
+		}
+		return candidates;
+	}
 }
