Index Management API integration test coverage

[cjcenizal]

This was generated as an output of #105863.

Note that some routes contain nuanced behavior, which I've described in the "Route notes" column. I assessed tests for error states as well. Generally, route error states aren't covered by our tests.

Legend

✅ - Tests are comprehensive
🔧 - Some functionality isn't tested
🚫 - Test is missing

Route coverage

Component templates

Route	Route notes	API test / error	Test notes
Create component template	Collision check	✅ 🚫
Delete component template	Split on comma	✅ ✅
Get all component templates		✅ 🚫
Get one component template		✅ 🚫
Component template privileges	Test is sparse, made up for by unit tests	✅ 🚫	We should test a user with cluster: { manage_index_templates: false } and verify they can't access the UI
Update component template		✅ ✅

Data streams

Route	Route notes	API test / error	Test notes
Delete data stream(s)		🔧 🚫
Get all data streams	Include stats option	✅ 🚫
Get one data stream	Include stats option	🔧 🚫

Indices

Route	Route notes	API test / error	Test notes
Clear cache	Bulk	✅ 🚫
Close	Bulk	🔧 🚫
Delete	Bulk	🔧 🚫
Flush	Bulk	🔧 🚫
Force merge	Bulk, maxNumSegments option	🔧 🚫
Freeze	Bulk, encodeURIComponent	🔧 🚫
List	Bulk, enrich, encodeURIComponent	✅ 🚫
Open	Bulk	🔧 🚫
Refresh	Bulk	🔧 🚫
Reload	Bulk, enrich, encodeURIComponent	✅ 🚫
Unfreeze	Bulk, encodeURIComponent	🔧 🚫

Mapping

Route	Route notes	API test / error	Test notes
Get mapping		✅ 🚫

Settings

Route	Route notes	API test / error	Test notes
Load settings		✅ 🚫
Update settings		✅ 🚫

Stats

Route	Route notes	API test / error	Test notes
Get stats		✅ 🚫

Index templates

Route	Route notes	API test / error	Test notes
Create index template	Collision check, legacy option	🔧 ✅
Delete index template	Bulk, legacy option	🔧 🚫
Get all index templates	Cloud-managed, includes legacy	🔧 🚫
Get one index template	Cloud-managed, legacy option	🔧 🚫
Simulate		🚫 🚫
Update index template	Exist check, legacy option	🔧 ✅

[elasticmachine]

Pinging @elastic/kibana-stack-management (Team:Stack Management)

[yuliacech]

Closing this issue: the team improved the api integration test coverage during a recent testing spike