[VizBuilder] Increase test coverage

[kavilla]

Parent task to fill in the gaps from the low initial coverage that the VisBuilder has.

Sub tasks:

• Add unit tests to functional code where it makes sense
• Investigate and document functional testing flow to see if they can be made easier to write and debug
• Add missing functional test workflows
• Add Vis Builder FTR tests to OpenSearch Dashboards Repo (set the appropriate env flag)

Missing unit tests

• src/plugins/wizard/public/application/utils/get_top_nav_config.tsx
• src/plugins/wizard/public/application/utils/validate_schema_state.ts
• src/plugins/wizard/public/application/components/data_tab/utils/get_available_fields.ts

Missing functional tests

• Save workflow
• View on dashboards
• Edit from dashboards
• Create from dashboards:
• Edit from Visualization listing
• Metric tests
• Bar chart tests
• Line chart tests
• Area Chart tests
• Drag and Drop test
• Change datasource

[kavilla]

[Follow-up]: Negative code coverage? Maybe we should have a rule if negative code coverage point to new functional tests.

[Follow-up 2]: Is there another way to calculate coverage accurately from a functional tests view point.

[joshuarrrr]

See also:

• [Vis Builder] Functional: create visualization, save it, go to save object management, inspect, make change and save, navigate to edit view, make change and save #1884
• [D&D] Functional: validate export/import of saved objects #1885

[ashwin-pc]

Save workflow is blocked by #2627 (comment). Will track adding a test workflow as a part of that separately. Closing this issue in the meantime.