tests: cleanup and ci hardening (#2397)
* tests: refactor and cleanup
* refactor: more consistent
* tests: vendor six
* tests: more xfails, nicer system
* tests: simplify to info
* tests: suggestions from @YannickJadoul and @bstaletic
* tests: restore some pypy tests that now pass
* tests: rename info to env
* tests: strict False/True
* tests: drop explicit strict=True again
* tests: reduce minimum PyTest to 3.1
diff --git a/tests/test_async.py b/tests/test_async.py
index e9292c9..df4489c 100644
--- a/tests/test_async.py
+++ b/tests/test_async.py
@@ -1,7 +1,8 @@
# -*- coding: utf-8 -*-
-import asyncio
import pytest
-from pybind11_tests import async_module as m
+
+asyncio = pytest.importorskip("asyncio")
+m = pytest.importorskip("pybind11_tests.async_module")
@pytest.fixture