Add py38-dev job to Travis

.travis.yml

@@ -23,6 +23,11 @@ env:
     - TOXENV=py37-pluggymaster PYTEST_NO_COVERAGE=1
     - TOXENV=py37-freeze PYTEST_NO_COVERAGE=1
 
+matrix:
+  allow_failures:
+    - python: '3.8-dev'
+      env: TOXENV=py38
+
 jobs:
   include:
     # Coverage tracking is slow with pypy, skip it.
@@ -35,6 +40,8 @@ jobs:
       python: '3.5'
     - env: TOXENV=py36
       python: '3.6'
+    - env: TOXENV=py38
+      python: '3.8-dev'
     - env: TOXENV=py37
     - &test-macos
       language: generic

tox.ini

@@ -9,6 +9,7 @@ envlist =
     py35
     py36
     py37
+    py38
     pypy
     {py27,py37}-{pexpect,xdist,trial,numpy,pluggymaster}
     py27-nobyte