Use PID based wsEndpoint file

[ghost]

Allows multiple Jest processes to connect to their own chromium instances

[ghost]

Issue #98 (comment)

[gregberge]

Thanks!

[izorg]

Looks like global setup WS_ENDPOINT_PATH is different from what PuppeteerEnvironment setup gets

[gregberge]

@izorg what do you mean? Do you experience a bug?

[izorg]

@neoziro yes, I got TypeError: Cannot read property 'removeListener' of undefined in 3.3.0 version. Output into the console the WS_ENDPOINT_PATH variable directly in node_modules folder from global.js & PuppeteerEnvironment.js and got different pid in the end. I can create a clean project to try to reproduce it if you can't reproduce it easily.

[gregberge]

@izorg hmm yes it makes sense. Jest runs test in parallel so it can't work like that. I revert it.

[ghost]

I've looked into the problem with a clean repo and I realized the reason I did not get the error @izorg found was because I was running a single testFile. Jest runs each testFile in parallel and does so with separate child process with different pids. If there is only one testFile, it does not run the test in a child process so the PID of Globals and PuppeteerEnvironment continue to match.

addressed in #115