Ensure the catalog controller's `Reconcile()` function is being properly unit tested

[everettraven]

operator-framework/catalogd#196 Updated the catalog controller's unit tests which resulted in the removal of using envtest for unit testing purposes. It was called out as part of that PR that we should look into refactoring the Reconcile() function in such a way that makes it easier to test only the logic that runs inside of the Reconcile() function:

A future tech debt item could be to investigate refactoring the Reconcile() function to make it easier to test the logic without using envtest.

[stevekuznetsov]

Factoring the apply logic into a library (example) and testing that in isolation is likely a better way to ensure correctness. If you do that, the rest of Reconcile() ends up being ~10 lines of code, which will remain static and unchanging forevermore. Visually inspecting the un-recoverable error case may be sufficient then.

[everettraven]

Factoring the apply logic into a library (example) and testing that in isolation is likely a better way to ensure correctness. If you do that, the rest of Reconcile() ends up being ~10 lines of code, which will remain static and unchanging forevermore. Visually inspecting the un-recoverable error case may be sufficient then.

This is along the lines of what I was thinking. As far as I am aware, both rukpak and operator-controller are using a similar Reconcile() function as catalogd so this would likely be useful across multiple OLMv1 components.