[Meta]Increase test coverage for Multiple Datasource feature support

[yujin-emma]

Is your feature request related to a problem? Please describe.

The test coverage for Multiple data source feature is not good enough. Some breaking change can be introduced without enough test to capture. We need to increase the test coverage for supporting this feature.

This meta issue is used to track the test coverage for MDS for 2.15 release
List the missing test cases and related action items here:

Unit Test:

1. custom_database_icon
2. data_source_aggregated_view
3. data_source_error_menu
4. data_source_item
5. data_source_multi_selectable
6. data_source_view
7. edit_data_source
8. toast_button
9. validation
   Integration and End-to-end Test:

Feature	Test Case	Expected Behavior	Location
Delete data source	When delete data source	confirmation popout	OSD
default data source	With empty data source list and hide local cluster, create the first data source	the first data source will be set as default	FT repo
	With empty data source list and not hide local cluster, create the first data source	the first data source will be set as default	FT repo
	With empty data source list and not hide local cluster	local cluster will be default data source	FT repo
	With non-empty data source list	default label can be displayed	FT repo
DataSourceView	When hide local cluster and pass empty string	nothing to render	FT repo
	When not hide local cluster and pass empty string	render local cluster as selectedOption	FT repo
	When hide local cluster and pass invalid data source id	Render default data source if exist default option	FT repo
	Render error toast if default option not exist	FT repo
	When not hide local cluster and pass invalid data source id	Render default data source if exist default option	FT repo
	Render error toast if default option not exist	FT repo
	When hide local cluster and only pass in valid data source id	Render the label by fetch dataSourceObj by the input id if this obj is not filtered out	FT repo
	Render error if the fetch dataSourceObj is filtered out	FT repo
	When not hide local cluster and only pass in valid data source id	Render the label by fetch dataSourceObj by the input id if this obj is not filtered out	FT repo
	Render error if the fetch dataSourceObj is filtered out	FT repo
	When hide local cluster and pass both id and label for selectedOption	Render selectedOption even if this option is filtered out	FT repo
	Render selectedOption if this option is not filtered out	FT repo
DataSourceSelector	When default option is provided, id is empty string while hide local cluster setting is true	Show toasts saying the data source is not available	FT repo
	When default option is provided, id is empty string while hide local cluster setting is false	Render local cluster	FT repo
	When there are compatible datasource options and default data source, hide local cluster	Display default data source should show up on the first load	FT repo
	When there are compatible datasource options and default data source, not hide local cluster	Display default data source should show up on the first load	FT repo
	When empty array is passed for default option and hide local cluster	Show placeholder text	FT repo
	When empty array is passed for default option and not hide local cluster	Show placeholder text	FT repo
	When invalid data source id is passed in and hide local cluster	Show toast saying the data source is not available	FT repo
	When invalid data source id is passed in and not hide local cluster	Show toast saying the data source is not available	FT repo
	When empty data source id is passed in and hide local cluster setting is set to false	Show local cluster on initial load	FT repo
	When there is default data source, but data source filter filters it out, and hide local cluster is set to false	Show local cluster	FT repo
	When all data sources are deleted, hide local cluster is set to true	Show toast saying no available data sources	FT repo
	When valid data source id is passed in	Show the data source regardless local cluster setting	FT repo
	Data source long name testing		FT repo
Data Source Selectable	When default option is provided, id is empty string while hide local cluster setting is true	Show toasts saying the data source is not available	FT repo
	When default option is provided, id is empty string while hide local cluster setting is false	Show local cluster	FT repo
	When there are compatible datasource options and default data source	Default data source should show up on the first load in regardless of the hide local cluster setting	FT repo
	When invalid data source id is passed in	Show toast saying the data source is not available in regardless of the hide local cluster setting	FT repo
	When there is default data source, but data source filter filters it out, and hide local cluster is set to false	Show local cluster	FT repo
	When there is default data source, but data source filter filters it out, and hide local cluster is set to true	Show toast saying the data source is not available	FT repo
	When all data sources are deleted, hide local cluster is set to true	Show toast saying no available data sources	FT repo
	When valid data source id is passed in	Show the data source	FT repo
DataSourceAggregatedView	No data source added and hide local cluster	Show warning for no data source connected	FT repo
	No data source added and not hide local cluster	Show local cluster	FT repo
	Incompatible data sources and hide local cluster	Show warning	FT repo
	Incompatible data sources and not hide local cluster	Show local cluster	FT repo
	When pass in data source options	Render data sources	FT repo
	When pass invalid data source id	Show error	FT repo
DataSourceAggregatedView list active	No data source added and hide local cluster	Show warning for no data source connected	FT repo
	No data source added and not hide local cluster	Show local cluster	FT repo
	When enable one data source and hide local cluster	Show the data source used on the current page	FT repo
	When enable one data source and not hide local cluster	Show the data source used on the current page and local cluster	FT repo
	When passed input contains invalid data source	Show the data source option but uncheck the invalid ones	FT repo
	When pass in local cluster but hide local cluster	Display empty	FT repo
	When all data sourced filtered out and hide local cluster	Show warning for no data source connected	FT repo
	When all data sourced filtered out and not hide local cluster	Only show local cluster	FT repo
Versions	Call fetch data source	Can get meta data from installed plugins	OSD and FT repo
Import saved objects	When enable data source	Can import saved object with specified data source under create new copy/check conflict and override/manual select override	OSD and FT repo
	When disable data source	Can import saved object from non-MDS cluster	OSD and FT repo
Add sample data	When disable data source	Can add sample data	OSD and FT repo
	When enable data source	Can add sample data	OSD and FT repo
Dev tools with MDS	When enable data source	Show default data source if it exists, other than local cluster, Can select other data source in available list, Show warning when no data source and hide local cluster	OSD and FT repo
	When disable data source	Not show anything	OSD and FT repo
TSVB with MDS	When enable data source	Pass in undefined activeOption when data_source_id is not present	OSD and FT repo
		Pass in pass in Local cluster if data_source_id: ''	OSD and FT repo
		pass in selected datasource if data_source_id: some-datasource	OSD and FT repo
		invalid/filtered out data_source_id should be handled by our selector component already	OSD and FT repo
	When disable data source	Ignore data_source_id field and just query from Local cluster	OSD and FT repo

Describe the solution you'd like

A clear and concise description of what you want to happen.

Cover as many as possible test cases for supporting multiple data source ( when enable data source )

A clear and concise description of any alternative solutions or features you've considered.

N/A
Add any other context or screenshots about the feature request here.

[BionIT]

For different cases of a same function or component, I would suggest to follow similar pattern in @huyaboo 's PR https://github.com/opensearch-project/OpenSearch-Dashboards/pull/6678/files#diff-5bee04d7a72154306ca30ebf14b62ae22546ca83e47c797a9e6892436269e7c8R293

[BionIT]

@yujin-emma For this meta issue, do we have any tasks remaining?