Safari headless test fails due to non-200 status code in Safari 12

[C-Saunders]

(Migrated from rustwasm/wasm-pack#418)

Running cargo test --target wasm32-unknown-unknown with a fresh, unmodified clone of the repository has a failing test in Safari 12.

Running headless tests in Safari with `safaridriver`
driver status: signal: 9
error: non-200 response code: 500
{"value":{"error":"session not created","message":"Request body does not contain required parameter 'capabilities'.","stacktrace":""}}

The issue seems to be that with Safari 12, by default, supports the W3C driver protocol, rather than the Selenium JSON protocol, as described in this Apple documentation.

I made an update that gets this working that you can see in this commit, but am concerned about dropping support for Safari < 12.

Please let me know if you'd like me to open a pull request with the above change, investigate further regarding support for older versions, or any other feedback.

Thanks!

[henriiik]

I ran into the same problem, it is also possible work around by passing the --legacy flag to safari driver.

ex.

SAFARIDRIVER_ARGS=--legacy cargo test --target wasm32-unknown-unknown

[alexcrichton]

Thanks for the report and links @C-Saunders! Also thanks for the tip @henriiik, this all makes sense!

I've posted a fix for this at #991 to hopefully enable us to both work in legacy mode and w3c