test: after each test, ensure that watcher only runs on one node (elected master)

Original commit: elastic/x-pack-elasticsearch@c5d0d4e1d3

src/test/java/org/elasticsearch/watcher/license/LicenseIntegrationTests.java

@@ -70,6 +70,11 @@ public class LicenseIntegrationTests extends AbstractWatcherIntegrationTests {
         return true;
     }
 
+    @Override
+    protected boolean checkWatcherRunningOnlyOnce() {
+        return false;
+    }
+
     @Test
     public void testEnableDisableBehaviour() throws Exception {
 

src/test/java/org/elasticsearch/watcher/test/AbstractWatcherIntegrationTests.java

@@ -141,6 +141,10 @@ public abstract class AbstractWatcherIntegrationTests extends ElasticsearchInteg
         return LicensePlugin.class;
     }
 
+    protected boolean checkWatcherRunningOnlyOnce() {
+        return true;
+    }
+
     @Before
     public void _setup() throws Exception {
         setupTimeWarp();
@@ -151,6 +155,9 @@ public abstract class AbstractWatcherIntegrationTests extends ElasticsearchInteg
     public void _cleanup() throws Exception {
         // Clear all internal watcher state for the next test method:
         logger.info("[{}#{}]: clearing watcher state", getTestClass().getSimpleName(), getTestName());
+        if (checkWatcherRunningOnlyOnce()) {
+            ensureWatcherOnlyRunningOnce();
+        }
         stopWatcher();
     }
 
@@ -487,6 +494,16 @@ public abstract class AbstractWatcherIntegrationTests extends ElasticsearchInteg
         ensureWatcherStopped(false);
     }
 
+    protected void ensureWatcherOnlyRunningOnce() {
+        int running = 0;
+        for (WatcherService watcherService : internalTestCluster().getInstances(WatcherService.class)) {
+            if (watcherService.state() == WatcherService.State.STARTED) {
+                running++;
+            }
+        }
+        assertThat("watcher should only run on the elected master node, but it is running on [" + running + "] nodes", running, equalTo(1));
+    }
+
     protected static InternalTestCluster internalTestCluster() {
         return (InternalTestCluster) ((WatcherWrappingCluster) cluster()).testCluster;
     }

src/test/java/org/elasticsearch/watcher/test/integration/NoMasterNodeTests.java

@@ -228,6 +228,7 @@ public class NoMasterNodeTests extends AbstractWatcherIntegrationTests {
     private void startElectedMasterNodeAndWait() throws Exception {
         internalTestCluster().startNode();
         ensureWatcherStarted(false);
+        ensureWatcherOnlyRunningOnce();
     }
 
 }