This does not produce a deprecation warning under PyPy, even pypy3.7
(last tested on 2021-03-12 using version 7.3.3-beta0).

--- a/_test/test_deprecation.py
+++ b/_test/test_deprecation.py
@@ -2,11 +2,12 @@
 
 from __future__ import print_function
 
+import platform
 import sys
 import pytest  # NOQA
 
 
-@pytest.mark.skipif(sys.version_info < (3, 7) or sys.version_info >= (3, 9),
+@pytest.mark.skipif(platform.python_implementation() == 'PyPy' or sys.version_info < (3, 7) or sys.version_info >= (3, 9),
                     reason='collections not available?')
 def test_collections_deprecation():
     with pytest.warns(DeprecationWarning):