Update tests to cover unexpected lower-the-rollout scenario

[bwaresiak]

Please review the release process for BrowserServicesKit here.

Required:

Task/Issue URL: https://app.asana.com/0/0/1209336234197627/f
iOS PR: n/a
macOS PR: n/a
What kind of version bump will this require?: Patch

Description:

See https://app.asana.com/0/0/1209336234197627/f for discussion.

Steps to test this PR:

Validate is scenario meets criteria outlined in the task.

---

Internal references:

Software Engineering Expectations
Technical Design Template

[alessandroboron]

Got a question. For this rollout, will we always replace the value in the configuration instead of adding other rollout steps?

I can see that we load the embeddedData always with one item.
I was looking at the isRolloutEnabled code and If we add an other item to the phase e.g.

"rollout": {
    "steps": [
       {
         "percent": 50.0    
       },
       {
         "percent": 5.0         
       }
    ]
}

there’s a chance that the feature is re-enabled?

[bwaresiak]

Subsequent steps should always be higher than the previous one, and each new step gives a chance for a device to be allocated in the rollout.

So if we change [50] to [5] then we can continue rollout by doing [5, 10] then [5, 10, 20] etc.

[alessandroboron]

Gotcha.

That means if we were to implement this hypotetic plan the percentages would map to those steps.

Day	Day of the Week	App Store Rollout	Remote Rollout (percentage)	Remote Rollout (steps)
Day 1	Monday	1%	50%	[50]
Day 2	Tuesday	2%	50%	[50]
Day 3	Wednesday	5% -> 100%	50% -> 5%	[5]
Day 4	Thursday	100%	10%	[5, 10]
Day 5	Friday	100%	25%	[5, 10, 25]
Day 6	Saturday	100%	25%	[5, 10, 25]
Day 7	Sunday	100%	25%	[5, 10, 25]
Day 8	Monday	100%	50%	[5, 10, 25, 50]
Day 9	Tuesday	100%	100%	[5, 10, 25, 50, 100]

[bwaresiak]

Yes, that should work out. Just make sure to update the config before bumping the release to 100% :)

[alessandroboron]

LGTM! Thanks for veryfing this!