[flink] 10/10: [hotfix][tests] Assert there is only one applicationId in ZooKeeper.

[ga...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

gary pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/flink.git

commit ad79e6953cdbd9571f0605810b7d5f42749b38f4
Author: gyao <ga...@data-artisans.com>
AuthorDate: Tue Sep 18 20:47:57 2018 +0200

    [hotfix][tests] Assert there is only one applicationId in ZooKeeper.
---
 flink-jepsen/src/jepsen/flink/client.clj | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/flink-jepsen/src/jepsen/flink/client.clj b/flink-jepsen/src/jepsen/flink/client.clj
index f513756..1ab987b 100644
--- a/flink-jepsen/src/jepsen/flink/client.clj
+++ b/flink-jepsen/src/jepsen/flink/client.clj
@@ -47,6 +47,12 @@
   (info "Waiting for path" path "in ZK.")
   (wait-for-zk-operation zk-client zk/exists path))
 
+(defn get-only-application-id
+  [coll]
+  (assert (= 1 (count coll)) (str "Expected 1 application id, got " coll ". "
+                                  "Failed to deploy the Flink cluster, or there are lingering Flink clusters."))
+  (first coll))
+
 (defn wait-for-children-to-exist
   [zk-client path]
   (wait-for-zk-operation zk-client zk/children path))
@@ -60,7 +66,7 @@
     (->
       (wait-for-children-to-exist zk-client "/flink")
       (deref)
-      (first))))
+      (get-only-application-id))))
 
 (defn watch-node-bytes
   [zk-client path callback]