Apple Game Center CI tests flaky

[mtrezza]

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• I am not just asking a question.
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• I can reproduce the issue with the latest version of Parse Server.

Issue Description

CI tests related to Apple Game Center are often failing:

1) Apple Game Center Auth adapter validateAuthData should validate
2) Apple Game Center Auth adapter validateAuthData invalid signature id
  - Expected 'error:0D0680A8:asn1 encoding routines:asn1_check_tlen:wrong tag' to be 'Apple Game Center - invalid signature'.

This only started recently and the tests only fail sometimes, so it may be an issue with test structure or the random order in which the tests are executed.

Steps to reproduce

See https://github.com/parse-community/parse-server/runs/6118780493?check_suite_focus=true#step:8:3965

Actual Outcome

Tests should pass

Expected Outcome

Tests fail sometimes

Environment

n/a

Server

• Parse Server version: [5.3.0-alpha.6](https://github.com/parse-community/parse-server/releases/tag/5.3.0-alpha.6)

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[dblythy]

I believe the certificate required for gamecenter tests should be https://static.gc.apple.com/public-key/gc-prod-6.cer, as explained here

[dblythy]

I think we also need to update the test signatures, however I can’t work out how to do this to get them to pass with the newer cert. @mtrezza any thoughts?

[mtrezza]

Closing via #7958 (comment), thanks @dblythy