Return empty arrays for performance.getEntries, other relevant methods

[flotwig]

Purpose (TL;DR)

Fix issues caused by applications which expect performance.getEntries, performance.getEntriesByName, and performance.getEntriesByType to return arrays (such as Facebook SDK - downstream issue: cypress-io/cypress#3625)

Right now, lolex clobbers these with () => undefined. Just using () => [] instead would fix this.

Background (Problem in detail)

MDN page for Performance functions: https://developer.mozilla.org/en-US/docs/Web/API/Performance

Only 5 have non-undefined return types. The other 2 (besides getEntries.*) are:

• now() - already done by lolex
• toJSON() - not handled, not sure if there's a good way to mock this value

Solution

Just have those 3 methods return [] when lolex.install() is called, instead of undefined

[benjamingr]

I can do a release next week when I'm back from DevDays

[flotwig]

@benjamingr Ping, would be awesome to see this released so we can incorporate this fix downstream :)

[fatso83]

doing it