FIX: Longer timeout if necessary.

test/test_async.cpp

@@ -53,11 +53,15 @@ TEST(test_async, retrieve_non_existing) {
   auto status = transaction->GetStatus();
   EXPECT_EQ(status.GetCode(), StatusCode::EXECUTING);
 
-  // wait some time
-  std::this_thread::sleep_for(1000ms);
+  // 1000ms are not always sufficient, when there is very high pipeline load.
+  auto count = 1000;
+  do {
+    // wait some time
+    std::this_thread::sleep_for(10ms);
 
-  // DONT call WaitForIt -> the transaction finishes in the back-ground
-  status = transaction->GetStatus();
+    // DONT call WaitForIt -> the transaction finishes in the background
+    status = transaction->GetStatus();
+  } while (--count > 0 && status.GetCode() == StatusCode::EXECUTING);
   EXPECT_EQ(status.GetCode(), TransactionStatus::TRANSACTION_ERROR().GetCode());
   ASSERT_EQ(status.GetCode(), StatusCode::GENERIC_TRANSACTION_ERROR);