Merge pull request #845 from DataDog/mar-kolya/fix-test-race-condition

Fix ApacheHttpAsync race condition

Author: mar-kolya

dd-java-agent/instrumentation/apache-httpasyncclient-4/src/test/groovy/ApacheHttpAsyncClientNullCallbackTest.groovy

@@ -1,6 +1,5 @@
 import datadog.trace.agent.test.base.HttpClientTest
 import datadog.trace.instrumentation.apachehttpasyncclient.ApacheHttpAsyncClientDecorator
-import io.opentracing.util.GlobalTracer
 import org.apache.http.client.methods.HttpGet
 import org.apache.http.impl.nio.client.HttpAsyncClients
 import org.apache.http.message.BasicHeader
@@ -34,10 +33,7 @@ class ApacheHttpAsyncClientNullCallbackTest extends HttpClientTest<ApacheHttpAsy
     Future future = client.execute(request, null)
     future.get()
     if (callback != null) {
-      // Request span is closed asynchronously even in regards to returned future so we have to wait here.
-      if (GlobalTracer.get().activeSpan() != null) {
-        blockUntilChildSpansFinished(1)
-      }
+      blockUntilChildSpansFinished(1)
       callback()
     }
     return 200

dd-java-agent/testing/src/main/groovy/datadog/trace/agent/test/AgentTestRunner.java

@@ -200,6 +200,10 @@ public static void assertTraces(
 
   public void blockUntilChildSpansFinished(final int numberOfSpans) throws InterruptedException {
     final DDSpan span = (DDSpan) io.opentracing.util.GlobalTracer.get().activeSpan();
+    if (span == null) {
+      // If there is no active span avoid getting an NPE
+      return;
+    }
     final PendingTrace pendingTrace = span.context().getTrace();
 
     while (pendingTrace.size() < numberOfSpans) {