Mailspring/spec/n1-spec-runner/time-override.coffee
Evan Morikawa 14514a3413 fix(specs): change spec scheduler back to setTimeout
Summary:
Adds a new `npm run test-window` that will launch specs in a window so you
can use the debugger

The spec window wouldn't close because `onbeforeunload` was unnecessarily
preventing close. This circumvents this in spec mode.

Most significantly I discovered we can't use the synchronous timer for the
promise scheduler anymore. Suppose you do:

```
it('should error', async () => {
  try {
    await doSomething()
    throw new Error("doSomething should have thrown!")
  } catch (err) {
    expect(err.message).toMatch(/my message/)
  }
})
```

The way async/await is transpiled, when `doSomething` throws, the error
will propagate all the way back up to the uncaughtPromiseException handler
before the `catch` gets called and registered. The transpilation method
assumes that when the function gets executed it can synchrously advance
beyond the call before the `then` or `catch` resolve. When the promise
scheduler is synchronous this doesn't happen.

I chose to use `setTimeout` instead of `process.nextTick` or
`setImmediate` as the promise scheduler. `setTimeout` seems to work better
with Chrome's async function call stacks. `nextTick` and `setImmediate`,
being Node methods, skip Chrome's async watchers.

Test Plan:
I talked with Juan about these changes, in an upcoming diff he will be
testing these in the context of our broader test suite.

Reviewers: mark, khamidou, halla, spang, juan

Reviewed By: juan

Differential Revision: https://phab.nylas.com/D3779
2017-01-25 17:43:11 -05:00

95 lines
2.6 KiB
CoffeeScript

_ = require 'underscore'
# Public: To make specs easier to test, we make all asynchronous behavior
# actually synchronous. We do this by overriding all global timeout and
# Promise functions.
#
# You must now manually call `advanceClock()` in order to move the "clock"
# forward.
class TimeOverride
@advanceClock = (delta=1) =>
@now += delta
callbacks = []
@timeouts ?= []
@timeouts = @timeouts.filter ([id, strikeTime, callback]) =>
if strikeTime <= @now
callbacks.push(callback)
false
else
true
callback() for callback in callbacks
@resetTime = =>
@now = 0
@timeoutCount = 0
@intervalCount = 0
@timeouts = []
@intervalTimeouts = {}
@originalPromiseScheduler = null
@enableSpies = =>
window.advanceClock = @advanceClock
window.originalSetTimeout = window.setTimeout
window.originalSetInterval = window.setInterval
spyOn(window, "setTimeout").andCallFake @_fakeSetTimeout
spyOn(window, "clearTimeout").andCallFake @_fakeClearTimeout
spyOn(window, "setInterval").andCallFake @_fakeSetInterval
spyOn(window, "clearInterval").andCallFake @_fakeClearInterval
spyOn(_._, "now").andCallFake => @now
# spyOn(Date, "now").andCallFake => @now
# spyOn(Date.prototype, "getTime").andCallFake => @now
@_setPromiseScheduler()
@_setPromiseScheduler: =>
@originalPromiseScheduler ?= Promise.setScheduler (fn) =>
window.originalSetTimeout(fn, 0)
@disableSpies = =>
window.advanceClock = null
jasmine.unspy(window, 'setTimeout')
jasmine.unspy(window, 'clearTimeout')
jasmine.unspy(window, 'setInterval')
jasmine.unspy(window, 'clearInterval')
jasmine.unspy(_._, "now")
Promise.setScheduler(@originalPromiseScheduler) if @originalPromiseScheduler
@originalPromiseScheduler = null
@resetSpyData = ->
window.setTimeout.reset?()
window.clearTimeout.reset?()
window.setInterval.reset?()
window.clearInterval.reset?()
Date.now.reset?()
Date.prototype.getTime.reset?()
@_fakeSetTimeout = (callback, ms) =>
id = ++@timeoutCount
@timeouts.push([id, @now + ms, callback])
id
@_fakeClearTimeout = (idToClear) =>
@timeouts ?= []
@timeouts = @timeouts.filter ([id]) -> id != idToClear
@_fakeSetInterval = (callback, ms) =>
id = ++@intervalCount
action = =>
callback()
@intervalTimeouts[id] = @_fakeSetTimeout(action, ms)
@intervalTimeouts[id] = @_fakeSetTimeout(action, ms)
id
@_fakeClearInterval = (idToClear) =>
@_fakeClearTimeout(@intervalTimeouts[idToClear])
module.exports = TimeOverride