Get specs passing on displays using certain device scale factors

[kevinsawicki]

Previously there were several BrowserWindow specs that failed when run on displays using a non-integer device scale factor such as 1.5 or an odd number value like 3.

This was due to the rounding of pixel values that occurs when converting content and window size and position.

This pull request switches these specs to use a assertBoundsEqual helper method that allows the expected value to be off by 1 when run on non-integer scale factor screen.

An alternative to this would be calling app.commandLine.appendSwitch('force-device-scale-factor', '2') in the specs themselves but then the runner window would be a possibly annoying scale factor that might make it hard to use for certain people.

/cc @haacked

[haacked]

I'll give this a shot.

[haacked]

I tried this out and a couple of tests still fail.

BrowserWindow.setMinimum/MaximumSize(width, height)

sets the maximum and minimum size of the window

AssertionError: [ 100, 100 ] deepEqual [ 100, 101 ]
    at assertBoundsEqual (C:\dev\work\electron\spec\api-browser-window-spec.js:1359:12)
    at Context.<anonymous> (C:\dev\work\electron\spec\api-browser-window-spec.js:289:7)
    at callFn (C:\dev\work\electron\spec\node_modules\mocha\lib\runnable.js:251:21)
    at Test.Runnable.run (C:\dev\work\electron\spec\node_modules\mocha\lib\runnable.js:244:7)
    at Runner.runTest (C:\dev\work\electron\spec\node_modules\mocha\lib\runner.js:374:10)
    at C:\dev\work\electron\spec\node_modules\mocha\lib\runner.js:452:12
    at next (C:\dev\work\electron\spec\node_modules\mocha\lib\runner.js:299:14)
    at C:\dev\work\electron\spec\node_modules\mocha\lib\runner.js:309:7
    at next (C:\dev\work\electron\spec\node_modules\mocha\lib\runner.js:248:23)
    at Immediate.<anonymous> (C:\dev\work\electron\spec\node_modules\mocha\lib\runner.js:276:5)

BrowserWindow.setContentBounds(bounds)

sets the content size and position

AssertionError: { x: 10, y: 10, width: 250, height: 250 } deepEqual { x: 10, y: 9, width: 250, height: 250 }
    at assertBoundsEqual (C:\dev\work\electron\spec\api-browser-window-spec.js:1359:12)
    at C:\dev\work\electron\spec\api-browser-window-spec.js:353:9
    at CallbacksRegistry.apply (C:\dev\work\electron\out\D\resources\electron.asar\common\api\callbacks-registry.js:54:39)
    at EventEmitter.<anonymous> (C:\dev\work\electron\out\D\resources\electron.asar\renderer\api\remote.js:274:21)
    at emitThree (events.js:116:13)
    at EventEmitter.emit (events.js:194:7)

Notice that deepEqual is still being called which doesn't allow for the margin of error.

Get specs passing on displays using non-integer device scale factor

So the thing is, on my machine I do have an integer scale factor. I've scaled things to 300% which is a scale factor of 3. Not sure why that would create the off by one errors though.

[kevinsawicki]

So the thing is, on my machine I do have an integer scale factor. I've scaled things to 300% which is a scale factor of 3. Not sure why that would create the off by one errors though.

Yeah, that is interesting, could you run process.argv from the Console tab of the devtools and include the value here of the device-scale-factor element?

[haacked]

"--device-scale-factor=3"

[kevinsawicki]

"--device-scale-factor=3"

Okay, thanks, yeah, perhaps because it is an odd number scaling up and down can cause some rounding.

[kevinsawicki]

@haacked can you try again on this branch? I adjusted the delta logic case to include odd number scale factors above 2.

[haacked]

That fixed it!

[zcbenz]

👍