Bug 1701652 - Don't let the platform be changed after Glean was initialized

[brizental]

No description provided.

[Dexterp37]

I have one additional concern: by doing this, if Glean is initialized in the code being tested (e.g. Rally inits Glean), then the tests might send pings because the uploader is no longer the one from the test platform. To cover these cases, and avoid the potential of submitting pings from tests, can we make testResetGlean use a mock default uploader is none is passed via the configuration?

[brizental]

I have one additional concern: by doing this, if Glean is initialized in the code being tested (e.g. Rally inits Glean), then the tests might send pings because the uploader is no longer the one from the test platform.

Note that testResetGlean always uninitializes before initializing. Therefore even if Glean is initialized in the code being tested before testResetGlean is called, the platform and config is still overwritten.

This is why I decided to rely on initialized to set the platform or not, instead of just checking if there is a platform there already. Writing this out gives me the vibe that it is fragile, but such fragility would be mitigated by work on Bug 1682771 and a clear testing state for Glean.