Update test requirements and add coverage to tox

Author: SmileyChris

setup.cfg

@@ -44,13 +44,12 @@ maintainer =
 dev =
     flake8>=3.7,<4
     tox>=3,<4
-    pytest>=3.2.5,<4
-    pytest-cov
-    pytest-asyncio; python_version>="3.4"
     Sphinx>=1.8,<2
-    coverage>=5.0,<6
 test =
-    pytest>=3.2.5,<4
+    pytest>=4,<5; python_version<"3"
+    pytest>5; python_version>="3"
+    pytest-cov
+    pytest-asyncio; python_version>="3.4"
     graphene>=2.0,<3
     gevent
     graphene>=2.0

tox.ini

@@ -1,5 +1,8 @@
 [tox]
-envlist = py27, py35, py36, py37, py38, flake8
+envlist = 
+    coverage_setup
+    py27, py35, py36, py37, py38, flake8
+    coverage_report
 
 [travis]
 python =
@@ -11,9 +14,22 @@ python =
 
 [testenv]
 extras = test
-commands = pytest
+commands = pytest --cov --cov-append --cov-report=
 
 [testenv:flake8]
 skip_install = true
 deps = flake8
 commands = flake8 graphql_ws
+
+[testenv:coverage_setup]
+skip_install = true
+deps = coverage
+commands = coverage erase
+
+[testenv:coverage_report]
+skip_install = true
+deps = coverage
+commands =
+  coverage html
+  coverage report --include="tests/*" --fail-under=100 -m
+  #coverage report --omit="tests/*" --fail-under=90 -m