This commit adds support to the `wasm-bindgen-test-runner` binary to
perform headless testing via browsers. The previous commit introduced a
local server to serve up files and run tests in a browser, and this
commit adds support for executing that in an automated fashion.
The general idea here is that each browser has a binary that implements
the WebDriver specification. These binaries (typically `foodriver` for
the browser "Foo") are interfaced with using HTTP and JSON messages. The
implementation was simple enough and the crates.io support was lacking
enough that a small implementation of the WebDriver protocol was added
directly to this crate.
Currently Firefox (`geckodriver`), Chrome (`chromedriver`), and Safari
(`safaridriver`) are supported for running tests. The test harness will
recognize env vars like `GECKODRIVER=foo` to specifically use one or
otherwise detects the first driver in `PATH`. Eventually we may wish to
automatically download a driver if one isn't found, but that isn't
implemented yet.
Headless testing is turned on with the `CI=1` env var currently to be
amenable with things like Travis and AppVeyor, but this may wish to grow
an explicit option to run headless tests in the future.
This commit starts to add support for in-browser testing with
`wasm-bindgen-test-runner`. The current idea here is that somehow it'll be
configured and it'll spawn a little HTTP server serving up files from the
filesystem. This has been tested in various ways but isn't hooked up just yet,
wanted to make sure this was somewhat standalone! Future support for actually
running these tests will be coming in later commits.
