Fix sync tests getting skipped in parallel mode.

[garg3133]

Fixes: #3786.

The issue here was that custom commands many times return an instance of NightwatchAPI instead of the actual command result. Due to this, when destructuring status from result, status was getting assigned the definition of .status() (a function) command instead of the status of the command run (a number).

Now, while being in parallel mode, reports from all test runs are sent to a common port (see here), but the postMessage method does not work with functions, and so it was failing for tests containing custom commands.

Due to this, while the test with custom commands was running fine, it was not getting reported on the terminal as well as in the HTML report, hence it seemed like it was getting skipped.

[github-actions]

Status

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[swrdfish]

@garg3133 were you able to add a test for this?

[garg3133]

@swrdfish I wasn't able to get it working, and after that my focus shifted to the namespace thing. But the gist of it is:

During parallel testing, Nightwatch creates separate workers for each test suite, but while doing so, it does not pass the custom settings defined in our tests and due to this, the settings defined in tests are not obeyed. And when I tried to modify the code so that it passes the settings to each worker, I'm getting the same error that this PR is solving, but at a different place (because settings may contain a function, Nightwatch is unable to pass the settings object to the workers).

[swrdfish]

After a debug session with @garg3133 , it looks like this fix needs more work.

[garg3133]

This PR is ready now.

[garg3133]

@AutomatedTester This also needs to go in our next release.

/cc: @gravityvi since this PR makes some changes around the work you did on worker threads. (Those changes are required to be able to use parallel testing in our unit tests, and have no connection with the actual issue.)

[garg3133]

@gravityvi @swrdfish Can you please review this PR once more? I've made some changes as suggested by Ravi and this PR looks good to me now.

(The let -> const changes in testsuite/index.js are done by Husky automatically.)