[GitHub] [kafka] ableegoldman commented on a change in pull request #9888: KAFKA-12194: use stateListener to catch each state change

[GitBox <gi...@apache.org>]

ableegoldman commented on a change in pull request #9888:
URL: https://github.com/apache/kafka/pull/9888#discussion_r558603115



##########
File path: streams/src/test/java/org/apache/kafka/streams/integration/AdjustStreamThreadCountTest.java
##########
@@ -90,24 +91,61 @@ public void setup() {
         );
     }
 
+    private void startStreamsAndWaitForRunning(final KafkaStreams kafkaStreams) throws InterruptedException {
+        kafkaStreams.start();
+        waitForRunning();
+    }
+
     @After
     public void teardown() throws IOException {
+        stateTransitionHistory.clear();
         purgeLocalStreamsState(properties);
     }
 
+    private void addStreamStateChangeListener(final KafkaStreams kafkaStreams) {
+        // we store each new state in state transition so that we won't miss any state change
+        kafkaStreams.setStateListener(
+            (newState, oldState) -> stateTransitionHistory.add(newState)
+        );
+    }
+
+    private void waitForRunning() throws InterruptedException {
+        waitForCondition(
+            () -> !stateTransitionHistory.isEmpty() &&
+                stateTransitionHistory.get(stateTransitionHistory.size() - 1).equals(KafkaStreams.State.RUNNING),
+            DEFAULT_DURATION.toMillis(),
+            () -> String.format("Client did not transit to state %s in %d seconds",
+                KafkaStreams.State.RUNNING, DEFAULT_DURATION.toMillis() / 1000)
+        );
+    }
+
+    // verify if state change from "before" state into "after" state

Review comment:
       Classic Bruno, can't sneak any inline comments past him :P 




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