Try to fix coveralls unstable result (#15800)

* Create one tox env for code coverage report

pytest-cov generated report in project root folder, not tox env folder.

* Add cov tox env to travis

* Coveralls seems expecting all build jobs upload

* Only upload coverage after cov env success

.travis.yml

@@ -13,7 +13,8 @@ matrix:
     - python: "3.5.3"
       env: TOXENV=typing
     - python: "3.5.3"
-      env: TOXENV=py35
+      env: TOXENV=cov
+      after_success: coveralls
     - python: "3.6"
       env: TOXENV=py36
     - python: "3.7"
@@ -45,4 +46,3 @@ deploy:
   on:
     branch: dev
     condition: $TOXENV = lint
-after_success: coveralls

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py35, py36, py37, py38, lint, pylint, typing
+envlist = py35, py36, py37, py38, lint, pylint, typing, cov
 skip_missing_interpreters = True
 
 [testenv]
@@ -11,6 +11,22 @@ setenv =
 ; fail.
 whitelist_externals = /usr/bin/env
 install_command = /usr/bin/env LANG=C.UTF-8 pip install {opts} {packages}
+commands =
+     pytest --timeout=9 --duration=10 {posargs}
+deps =
+     -r{toxinidir}/requirements_test_all.txt
+     -c{toxinidir}/homeassistant/package_constraints.txt
+
+[testenv:cov]
+basepython = {env:PYTHON3_PATH:python3}
+setenv =
+    PYTHONPATH = {toxinidir}:{toxinidir}/homeassistant
+; both temper-python and XBee modules have utf8 in their README files
+; which get read in from setup.py. If we don't force our locale to a
+; utf8 one, tox's env is reset. And the install of these 2 packages
+; fail.
+whitelist_externals = /usr/bin/env
+install_command = /usr/bin/env LANG=C.UTF-8 pip install {opts} {packages}
 commands =
      pytest --timeout=9 --duration=10 --cov --cov-report= {posargs}
 deps =