--hypothesis-show-statistics doesn't work with pytest-xdist

[DRMacIver]

If you use the flag while running with xdist then you'll get no statistics. This is presumably because the tests are running in a different process than the collector, so the data isn't getting communicated back.

To reproduce e.g. run pytest --hypothesis-show-statistics tests/cover/test_testdecorators.py, which will use the default Hypothesis configuration and run with two child runners and show no statistics.

[Zac-HD]

Related to pytest-dev/pytest-xdist#79. Our current code, which doesn't work with xdist, is:

hypothesis/hypothesis-python/src/hypothesis/extra/pytestplugin.py

Lines 107 to 113 in fe60c8a

	def pytest_runtest_makereport(item, call):
	report = (yield).get_result()
	if hasattr(item, 'hypothesis_report_information'):
	report.sections.append((
	'Hypothesis',
	'\n'.join(item.hypothesis_report_information)
	))

It looks like we'll need to write some special-case logic to pass the report string back to the master instance when running under xdist, and probably also to receive the data. See e.g. the hook docs and xdist/workermanage.py as starting points.

---

Update: the reporting quoted above works just fine; it was relying on the global gathered_statistics dict that broke our reporting under xdist. PR incoming.