Follow-up from "Refactor Service#test to use service object"

Everyone can contribute. Help move this issue forward while earning points, leveling up and collecting rewards.

• Work on this issue
• Close this issue

The following discussion from !31854 (merged) should be addressed:

• @patrickbajao started a discussion: (+7 comments)

  Since we are stubbing the test method of the integration, I think we can just use a double (e.g. instance_double(Service)) for this (and other instances where we define integration). WDYT?

There is also a relevant discussion in !31854 (diffs, comment 347154801)

Context

The discussion is about removing / reducing the coupling between the Service model (an integration) and the service object Integrations::Test::ProjectService.

Right now, the event param is optional thus we need some logic to have a proper fallback. This is required because the frontend does not currently pass in a value for the event. Ideally, once the frontend passes this value, we should be able to refactor and remove this coupling and improve the code a bit.