Only run PDF comparison and coverage for one Python version

tox.ini

@@ -1,19 +1,23 @@
 [tox]
-envlist = py27,py35,py36,py37
+envlist = py27,py36,py37
 
 [testenv]
 commands =
-    python setup.py test -q {posargs}
+    zope-testrunner -vpc1 --test-path ./src
+pip_pre = True
 deps =
-    Pillow
-    Pygments
-    coverage
-    lxml
-    PyPDF2
-    reportlab
-    setuptools
-    six
-    zope.interface
-    zope.pagetemplate
-    zope.schema
-    zope.testrunner
+    .[test]
+
+[testenv:py37]
+# Python 3.7 is the designated coverage report and pdf comparison run.
+basepython = python3.7
+passenv = TRAVIS TRAVIS_JOB_ID TRAVIS_BRANCH
+commands =
+    coverage erase
+    coverage run {envbindir}/zope-testrunner -vpc1 --all --test-path ./src
+    coverage xml
+    coverage report -m
+pip_pre = True
+deps =
+    {[testenv]deps}
+    coverage<=4.9999