[2.11]Fix gantt chart UI test failing on empty index-pattern fields

[Qxisylolo]

Description

Fixes the gantt-chart-dashboards/gantt_ui.spec.js test.

Root cause

1. Empty index-pattern fields attribute. The test created the jaeger
   index pattern with only a title, leaving its fields attribute empty.
   The visualization editor reads the stored fields list to populate its
   field dropdowns — so every dropdown in the Gantt editor (Event, Start time,
   Duration) showed no options, and the chart could not be configured. The
   test then hung on cy.contains('spanID') until it timed out.

opensearch-project/OpenSearch-Dashboards#11653 introduces the error: An index-pattern created with only a title → fields stays empty → editor dropdowns are empty → the gantt chart can't be configured

test result

yarn cypress:run-without-security --browser electron \
  --spec cypress/integration/plugins/gantt-chart-dashboards/gantt_ui.spec.js

yarn run v1.22.19
$ env TZ=America/Los_Angeles NO_COLOR=1 cypress run --headless --env SECURITY_ENABLED=false --browser electron --spec cypress/integration/plugins/gantt-chart-dashboards/gantt_ui.spec.js

====================================================================================================

  (Run Starting)

  ┌────────────────────────────────────────────────────────────────────────────────────────────────┐
  │ Cypress:        9.5.4                                                                          │
  │ Browser:        Electron 94 (headless)                                                         │
  │ Node Version:   v22.23.0 (/Users/qianxisy/.local/share/mise/installs/node/22.23.0/bin/node)    │
  │ Specs:          1 found (plugins/gantt-chart-dashboards/gantt_ui.spec.js)                      │
  │ Searched:       cypress/integration/plugins/gantt-chart-dashboards/gantt_ui.spec.js            │
  └────────────────────────────────────────────────────────────────────────────────────────────────┘


────────────────────────────────────────────────────────────────────────────────────────────────────
                                                                                                    
  Running:  plugins/gantt-chart-dashboards/gantt_ui.spec.js                                 (1 of 1)
Browserslist: caniuse-lite is outdated. Please run:
npx browserslist@latest --update-db

Why you should do it regularly:
https://github.com/browserslist/browserslist#browsers-data-updating


  Dump test data
    ✓ Indexes test data for gantt chart

  Save a gantt chart
    ✓ Creates and saves a gantt chart (17703ms)

  Render and configure a gantt chart
    ✓ Renders no data message
    ✓ Renders the chart (5779ms)

  Configure panel settings
    ✓ Changes y-axis label
    ✓ Changes x-axis label
    ✓ Changes time formats (10285ms)
    ✓ Hides legends

  Add gantt chart to dashboard
    ✓ Adds gantt chart to dashboard


  9 passing (58s)


  (Results)

  ┌────────────────────────────────────────────────────────────────────────────────────────────────┐
  │ Tests:        9                                                                                │
  │ Passing:      9                                                                                │
  │ Failing:      0                                                                                │
  │ Pending:      0                                                                                │
  │ Skipped:      0                                                                                │
  │ Screenshots:  0                                                                                │
  │ Video:        true                                                                             │
  │ Duration:     57 seconds                                                                       │
  │ Spec Ran:     plugins/gantt-chart-dashboards/gantt_ui.spec.js                                  │
  └────────────────────────────────────────────────────────────────────────────────────────────────┘


  (Video)

  -  Started processing:  Compressing to 32 CRF                                                     
  -  Finished processing: /Users/qianxisy/co404/testss/Opensearch-dashboards-function    (3 seconds)
                          al-test/cypress/videos/plugins/gantt-chart-dashboards/gantt               
                          _ui.spec.js.mp4                                                           


====================================================================================================

  (Run Finished)


       Spec                                              Tests  Passing  Failing  Pending  Skipped  
  ┌────────────────────────────────────────────────────────────────────────────────────────────────┐
  │ ✔  plugins/gantt-chart-dashboards/gant      00:57        9        9        -        -        - │
  │    t_ui.spec.js                                                                                │
  └────────────────────────────────────────────────────────────────────────────────────────────────┘
    ✔  All specs passed!                        00:57        9        9        -        -        -  

✨  Done in 75.90s.

Issues Resolved

[List any issues this PR will resolve]

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[github-actions]

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🧪 PR contains tests

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[github-actions]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	Guard against missing fields response Guard against a missing or non-array resp.body.fields before stringifying it, otherwise the index pattern may be created with fields: undefined (as a JSON string) and reintroduce the original empty-fields failure. Fallback to an empty array to make the test robust. cypress/integration/plugins/gantt-chart-dashboards/gantt_ui.spec.js [46-59] }).then((resp) => { + const fields = Array.isArray(resp.body && resp.body.fields) ? resp.body.fields : []; cy.request({ method: 'POST', failOnStatusCode: false, url: `api/saved_objects/index-pattern/${INDEX}`, headers: { 'content-type': 'application/json', 'osd-xsrf': true }, body: JSON.stringify({ attributes: { title: INDEX, - fields: JSON.stringify(resp.body.fields), + fields: JSON.stringify(fields), }, }), }); }); Suggestion importance[1-10]: 4 __ Why: The suggestion adds a defensive fallback for resp.body.fields to prevent the index pattern from being created with an undefined fields attribute. It's a minor robustness improvement for a test setup, but the API call is expected to return fields for the indexed data.	Low

[wanglam]

LGTM. The fix correctly addresses the root cause — index-pattern created without fields attribute caused empty dropdowns in the gantt chart editor. The approach (refresh=wait_for + _fields_for_wildcard + store fields) mirrors how OSD itself creates index patterns. Clean and self-maintaining.