Fix date_nanos formatting for formats without fractional seconds (ela…

…stic#43114)

* Fix formatting for formats without S... part

* Add jest test catching the bug

src/legacy/core_plugins/kibana/common/field_formats/types/date_nanos.js

@@ -26,13 +26,14 @@ import _ from 'lodash';
  * part when formatting with moment.js -> e.g. [SSS]
  */
 export function analysePatternForFract(pattern) {
-
   const fracSecMatch = pattern.match('S+'); //extract fractional seconds sub-pattern
+  const fracSecMatchStr = fracSecMatch ? fracSecMatch[0] : '';
+
   return {
-    length: fracSecMatch[0] ? fracSecMatch[0].length : 0,
-    patternNanos: fracSecMatch[0],
+    length: fracSecMatchStr.length,
+    patternNanos: fracSecMatchStr,
     pattern,
-    patternEscaped: fracSecMatch[0] ? pattern.replace(fracSecMatch[0], `[${fracSecMatch[0]}]`) : '',
+    patternEscaped: fracSecMatchStr ? pattern.replace(fracSecMatch, `[${fracSecMatch}]`) : '',
   };
 }
 
@@ -42,11 +43,9 @@ export function analysePatternForFract(pattern) {
  * milliseconds, the fractional pattern is replaced by the fractional value of the raw timestamp
  */
 export function formatWithNanos(dateMomentObj, valRaw, fracPatternObj) {
-
   if (fracPatternObj.length <= 3) {
     //S,SS,SSS is formatted correctly by moment.js
     return dateMomentObj.format(fracPatternObj.pattern);
-
   } else {
     //Beyond SSS the precise value of the raw datetime string is used
     const valFormatted = dateMomentObj.format(fracPatternObj.patternEscaped);
@@ -99,7 +98,7 @@ export function createDateNanosFormat(FieldFormat) {
 
           const date = moment(val);
 
-          if(typeof val !== 'string' && date.isValid()) {
+          if (typeof val !== 'string' && date.isValid()) {
             //fallback for max/min aggregation, where unixtime in ms is returned as a number
             //aggregations in Elasticsearch generally just return ms
             return date.format(fallbackPattern);

src/legacy/core_plugins/kibana/common/field_formats/types/date_nanos.test.js

@@ -0,0 +1,42 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { analysePatternForFract } from './date_nanos';
+
+test('analysePatternForFract using timestamp format containing fractional seconds', () => {
+  expect(analysePatternForFract('MMM, YYYY @ HH:mm:ss.SSS')).toMatchInlineSnapshot(`
+        Object {
+          "length": 3,
+          "pattern": "MMM, YYYY @ HH:mm:ss.SSS",
+          "patternEscaped": "MMM, YYYY @ HH:mm:ss.[SSS]",
+          "patternNanos": "SSS",
+        }
+    `);
+});
+
+test('analysePatternForFract using timestamp format without fractional seconds', () => {
+  expect(analysePatternForFract('MMM, YYYY @ HH:mm:ss')).toMatchInlineSnapshot(`
+    Object {
+      "length": 0,
+      "pattern": "MMM, YYYY @ HH:mm:ss",
+      "patternEscaped": "",
+      "patternNanos": "",
+    }
+  `);
+});