Fix HistoryIntegrationTests timestamp comparsion (elastic#38505)

When the millisecond part of a timestamp is 0 the toString
representation in java-time is omitting the millisecond part (joda was
not). The Search response is returning timestamps formatted with
WatcherDateTimeUtils, therefore comparisons of strings should be done
with the same formatter

relates elastic#27330

x-pack/plugin/watcher/src/test/java/org/elasticsearch/xpack/watcher/test/integration/HistoryIntegrationTests.java

@@ -17,12 +17,15 @@
 import org.elasticsearch.xpack.core.watcher.actions.ActionStatus;
 import org.elasticsearch.xpack.core.watcher.client.WatchSourceBuilder;
 import org.elasticsearch.xpack.core.watcher.input.Input;
+import org.elasticsearch.xpack.core.watcher.support.WatcherDateTimeUtils;
 import org.elasticsearch.xpack.core.watcher.support.xcontent.XContentSource;
 import org.elasticsearch.xpack.core.watcher.watch.WatchStatus;
 import org.elasticsearch.xpack.watcher.support.search.WatcherSearchTemplateRequest;
 import org.elasticsearch.xpack.watcher.test.AbstractWatcherIntegrationTestCase;
 import org.elasticsearch.xpack.watcher.trigger.schedule.IntervalSchedule;
+import org.hamcrest.Matcher;
 
+import java.time.ZonedDateTime;
 import java.util.Locale;
 
 import static org.elasticsearch.common.xcontent.XContentFactory.jsonBuilder;
@@ -172,10 +175,10 @@ public void testThatHistoryContainsStatus() throws Exception {
         assertThat(active, is(status.state().isActive()));
 
         String timestamp = source.getValue("status.state.timestamp");
-        assertThat(timestamp, is(status.state().getTimestamp().toString()));
+        assertThat(timestamp, isSameDate(status.state().getTimestamp()));
 
         String lastChecked = source.getValue("status.last_checked");
-        assertThat(lastChecked, is(status.lastChecked().toString()));
+        assertThat(lastChecked, isSameDate(status.lastChecked()));
 
         Integer version = source.getValue("status.version");
         int expectedVersion = (int) (status.version() - 1);
@@ -196,4 +199,14 @@ public void testThatHistoryContainsStatus() throws Exception {
         assertThat(mappingSource.getValue("doc.properties.status.properties.status"), is(nullValue()));
         assertThat(mappingSource.getValue("doc.properties.status.properties.status.properties.active"), is(nullValue()));
     }
+
+
+    private Matcher<String> isSameDate(ZonedDateTime zonedDateTime) {
+        /*
+        When comparing timestamps returned from _search/.watcher-history* the same format of date has to be used
+        during serialisation to json on index time.
+        The toString of ZonedDateTime is omitting the millisecond part when is 0. This was not the case in joda.
+         */
+        return is(WatcherDateTimeUtils.formatDate(zonedDateTime));
+    }
 }