Start testing Python 3.8 (#637)

.travis.yml

@@ -11,11 +11,12 @@ matrix:
     - python: "3.5"
     - python: "3.6"
     - python: "3.7"
-    - python: "3.8-dev"
+    - python: "3.8"
+    - python: "3.9-dev"
     - python: "pypy2.7-6.0"
     - python: "pypy3.5-6.0"
   allow_failures:
-    - python: "3.8-dev"
+    - python: "3.9-dev"
 
 cache:
   directories:

setup.py

@@ -56,11 +56,10 @@ def run_tests(self):
     python_requires=">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*",
     tests_require=[
         "pytest >= 4.6.2, < 4.7",
-        "pytest-mock >= 1.10.4",
-        "pytest-xdist >= 1.28.0",
-        "pytest-cov >= 2.7.1",
-        # coverage 5.0 pre-releases don't work, and setuptools doesn't ignore
-        # pre-releases (cf. https://github.com/pypa/setuptools/issues/855)
+        "pytest-mock >= 2.0.0",
+        "pytest-xdist >= 1.31.0",
+        "pytest-cov >= 2.8.1",
+        # TODO: upgrade to coverage 5 when we drop support for Python 3.4
         "coverage >= 4.5.3, < 5",
     ],
     cmdclass={"test": PyTest},

tox.ini

@@ -9,6 +9,7 @@ envlist = py27,
           py35,
           py36,
           py37,
+          py38,
           pypy,
           pypy3,
           lint
@@ -26,7 +27,7 @@ passenv = LDFLAGS CFLAGS
 
 [testenv:fmt]
 description = run code formatting using black
-basepython = python3.7
+basepython = python3.8
 deps = black
 commands = black . {posargs}
 skip_install = true