Last version of pytest for pypy is 4.6.11;

Also latest version pytest-cov is not compatible with pytest 5.+

https://travis-ci.org/github/syrusakbary/promise/jobs/708528307

 Could not find a version that satisfies the requirement pytest>=5.4.3 (from promise==2.3) (from versions: 2.0.0, ......... 4.6.10, 4.6.11)

https://travis-ci.org/github/syrusakbary/promise/jobs/708523881

E   AttributeError: type object 'Function' has no attribute 'from_parent'

latest pytest does not support python 2

setup.py

@@ -14,15 +14,15 @@
 IS_PY3 = sys.hexversion >= 0x03000000
 
 tests_require = [
-    "pytest>=2.7.3",
+    "pytest>4.1.0,<=4.6.11",
     "pytest-cov",
     "coveralls",
     "futures",
     "pytest-benchmark",
     "mock",
 ]
 if IS_PY3:
-    tests_require += ["pytest-asyncio"]
+    tests_require += ["pytest-asyncio<0.14.0"]
 
 
 setup(