Attempt at fixing the tests in master

[DeMoorJasper]

↪️ Pull Request

Closes #2842 closes #2935

🚨 Test instructions

yarn test shouldn't throw errors

[mischnic]

Related: #2842

[DeMoorJasper]

This is related to babel issues afaik, skipped it for now as babel was locked to <7.4 due to bugs.

[mischnic]

locked to <7.4 due to bugs.

How long will it stay it that way?

[DeMoorJasper]

Not sure Devon locked it, perhaps the bugs have already been fixed

cc @devongovett

[mischnic]

One issue atm with the old babel: This experimental syntax requires enabling the parser plugin: 'objectRestSpread' if a package contains rest spread (which isn't even a proposal anymore)

[devongovett]

I believe babel is fixed now, so we can upgrade it again.

[mischnic]

The tests pass on my machine, but the output is strange:

  FSCache
    ✓ should create directory on ensureDirExists (76ms)
(node:9100) UnhandledPromiseRejectionWarning: #<Object>
(node:9100) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:9100) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
(node:9100) UnhandledPromiseRejectionWarning: #<Object>
(node:9100) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 2)
    ✓ should cache resources (81ms)
    ✓ should return null for invalidated resources
    ✓ should remove file on delete (72ms)
    ✓ should remove from invalidated on write (63ms)

[DeMoorJasper]

@mischnic that's very strange but probably not caused by this PR

[DeMoorJasper]

Opened a new PR #2990