Run tests for python 2.6 and 3.7, too

.travis.yml

@@ -2,10 +2,13 @@ sudo: false
 dist: trusty
 language: python
 python:
+  - 2.6
+  - 2.7
   - 3.6
+  - 3.7-dev
 
 install:
-  - pip install tox
+  - pip install tox tox-travis
 
 script:
-  - tox -e check-py27,check-py36,coveralls
+  - tox

tox.ini

@@ -1,28 +1,42 @@
 [tox]
-envlist = flake8, pylint, check-{py27,py36}
+envlist = flake8, pylint, py{26,27,36,37}
 skipsdist = true
 skip_missing_interpreters = True
 
 [testenv]
 basepython = python2.7
+deps =
+    py{26,27,36,37}: pytest-cov
+    py{27,36,37}: pytest>=3.5.1
+    py26: pytest
 
 [base]
 passenv = *
 setenv =
     PYTHONPATH = {toxinidir}/src
     LC_ALL = C
-deps =
-    pytest-cov
-    pytest>=3.5.1
 changedir = {toxinidir}/tests
 covtarget = network_connections
 pytesttarget = .
 
-[testenv:check-py27]
+[testenv:py26]
+passenv = {[base]passenv}
+setenv =
+    {[base]setenv}
+hangedir = {[base]changedir}
+basepython = python2.6
+commands =
+    pytest \
+        --durations=5 \
+        --cov={[base]covtarget} \
+        --cov-report=html:htmlcov-py26 --cov-report=term \
+        {posargs} \
+        {[base]pytesttarget}
+
+[testenv:py27]
 passenv = {[base]passenv}
 setenv =
     {[base]setenv}
-deps = {[base]deps}
 changedir = {[base]changedir}
 basepython = python2.7
 commands =
@@ -33,11 +47,10 @@ commands =
         {posargs} \
         {[base]pytesttarget}
 
-[testenv:check-py36]
+[testenv:py36]
 passenv = {[base]passenv}
 setenv =
     {[base]setenv}
-deps = {[base]deps}
 changedir = {[base]changedir}
 basepython = python3.6
 commands =
@@ -48,6 +61,20 @@ commands =
         {posargs} \
         {[base]pytesttarget}
 
+[testenv:py37]
+passenv = {[base]passenv}
+setenv =
+    {[base]setenv}
+changedir = {[base]changedir}
+basepython = python3.7
+commands =
+    pytest \
+        --durations=5 \
+        --cov={[base]covtarget} \
+        --cov-report=html:htmlcov-py37 --cov-report=term \
+        {posargs} \
+        {[base]pytesttarget}
+
 [testenv:pylint]
 setenv =
     {[base]setenv}
@@ -81,3 +108,10 @@ addopts = -rxs
 
 [flake8]
 show_source = True
+
+[travis]
+python =
+  2.6: py26
+  2.7: py27,coveralls
+  3.6: py36
+  3.7: py37