This corrects/normalizes license headers in misc. files, such as
config files, docs, build tools, tests, and externs. This does not
affect the compiled output, and is only done for consistency.
Issue #2638
Change-Id: I9d8da2de55243b08d7df2b743aac73c6f15e858a
This adds our first screenshot-based layout tests and the
infrastructure to use WebDriver for screenshots through Karma.
This new kind of test will be skipped in any non-WebDriver context.
There are many pieces to this system.
First, we update the Karma WebDriver launcher to a newly-released
version that lets us access the client spec object from the launcher.
Second, we build a Karma middleware plugin to respond to HTTP requests
from the tests. We handle /screenshot/isSupported and return a bool
so tests can be skipped on non-WebDriver launchers. We also handle
/screenshot/diff to take the screenshot and compare it to a known-good
version.
The screenshot is a full-page screenshot, since element screenshots
don't work consistently across all the browsers in our test lab. The
screenshot is then cropped to a rectangle specified in the request.
This rectangle is measured to match a specific element, so in
practice, we are screenshotting just one element.
Browsers use sub-pixel rendering, effectively rendering at a scale
larger than the "pixels" seen by JS. The screenshot comes in at this
scale, so the requested cropping rectangle is scaled to match, then
the cropped screenshot is scaled down to the JS-measured size.
Because of sub-pixel rendering, element offsets can be non-integer
numbers. Normally, Karma puts the tests in a iframe, above which is a
variable-height banner showing which devices are connected to Karma
and what state they are in. So this variation and the lack of integer
offsets means we can run into stability issues due to rounding errors.
To make offsets consistent and improve stability of the screenshots,
this banner is now disabled in our Karma config.
The cropping, scaling, and diffing of images is handled Karma-side by
a node module called Jimp.
Before we start the layout tests for UITextDisplayer, we use a node
module in the browser called fontfaceonload to wait for our web fonts
to be fully loaded. This module is a polyfill that polls on IE and
uses a standard API in modern browsers to wait for our font to load.
This is all wrapped into a new test util called waitForFont.
Screenshots are stored in test/test/assets/screenshots/ and are
organized into folders by platform and browser and named according to
an identifier specified by each test case. The new screenshot is
written to disk with the suffix "-new", and a diff image is written
with the suffix "-diff". When a test fails, we can review the changes
in a browser with test/test/assets/screenshots/review.html. The
known-good screenshots can be updated with the new tool
build/updateScreenshots.py.
Change-Id: Ib477fd3c459de466c6dc91e9a60d3e2579164b12
Joey Parrish