python-coveralls in travis does not find coverage

I'm trying to setup a small python library with coveralls.io through travis-ci.

The current structure of the library is:

libconfig
├── .coverage
├── .coveragerc
├── .coveralls.yml
├── LICENSE
├── README.md
├── REQUIREMENTS
├── .gitignore
├── .travis.yml
├── libconfig
│   ├── __init__.py
│   ├── config.py
│   ├── evaluator.py
│   ├── tests
│   │   └── test_libconfig.py
│   └── util.py
├── package.json
├── setup.cfg
└── setup.py

My .coveragerc looks like this:

[run]
branch = False
omit = */tests/*

[report]
# Regexes for lines to exclude from consideration
exclude_lines =
    # Have to re-enable the standard pragma
    pragma: no cover

    # Don't complain about missing debug-only code:
    def __repr__
    if self\.debug

    # Don't complain if tests don't hit defensive assertion code:
    raise AssertionError
    raise NotImplementedError
    raise IOError
    raise ValueError

    # Don't complain if non-runnable code isn't run:
    if 0:
    if __name__ == .__main__.:

show_missing = True

ignore_errors = True

[html]
directory = coverage_html_report

and when I locally run the pytests, it does give me the coverage:

pytest --cov-config .coveragerc --cov=libconfig libconfig/tests
=========================== test session starts ============================
platform darwin -- Python 2.7.12, pytest-3.4.1, py-1.5.2, pluggy-0.6.0
rootdir: /Users/bonet/SandBox/libconfig, inifile:
plugins: cov-2.5.1
collected 5 items

libconfig/tests/test_libconfig.py .....          [100%]

---------- coverage: platform darwin, python 2.7.12-final-0 ----------
Name                     Stmts   Miss  Cover   Missing
------------------------------------------------------
libconfig/__init__.py        1      0   100%
libconfig/config.py        116      0   100%
libconfig/evaluator.py      20      0   100%
libconfig/util.py           34      0   100%
------------------------------------------------------
TOTAL                      171      0   100%


========================= 5 passed in 1.56 seconds =========================

Then, I have my .travis.yml configuration file:

language: python

python:
- '2.7'
- '3.5'
- '3.6'

install:
  - pip install -r REQUIREMENTS
  - pip install coverage coveralls
  - pip install python-coveralls
  - pip install pytest pytest-cov

script:
  - python setup.py install
  - pytest --cov-config .coveragerc --cov=libconfig libconfig/tests
  - coverage report --show-missing

after_success:
  - coveralls

But, when this runs in travis-ci, it does not give me any coverage:

The command "pytest --cov-config .coveragerc --cov=libconfig libconfig/tests" exited with 0.
$ coverage report --show-missing
Name                     Stmts   Miss  Cover   Missing
------------------------------------------------------
libconfig/__init__.py        1      1     0%   8
libconfig/config.py        116    116     0%   13-404
libconfig/evaluator.py      20     20     0%   13-47
libconfig/util.py           34     34     0%   9-68
------------------------------------------------------
TOTAL                      171    171     0%   
The command "coverage report --show-missing" exited with 0.

I've been looking around, but I haven't found a solution that would solve this issue, any help will be very appreciated.

So, this took a while, but I did find a solution, which can be fully seen in the libconfig repo that initiated this question.

Basically, I now run the commands inside tox, with a configuration file (tox.ini) such as:

[tox]
envlist = py27, py35, py36
skip_missing_interpreters = true

[testenv]
changedir = libconfig/tests
commands =
    python -c "import libconfig; print(libconfig.__version__)"
    coverage erase
    pytest --basetemp={envtmpdir} --cov-config {toxinidir}/.coveragerc --cov-report xml:/tmp/cov-single.xml --cov=libconfig
    coverage report --show-missing
deps =
    -rREQUIREMENTS
    pytest
    pytest-cov
    coverage
    coveralls
    python-coveralls

which makes sure to create the XML coverage report and a .travis.yml looking like:

language: python
sudo: false
branches:
  only:
  - master
  - "/^v\\d+\\.\\d+(\\.\\d+)?(-\\S*)?$/"
matrix:
  include:
    - python: 2.7
      env: TOXENV=py27
      os: linux
    - python: 3.5
      env: TOXENV=py35
      os: linux
    - python: 3.6
      env: TOXENV=py36
      os: linux
      after_success:
        - pwd
        - coveralls --data_file libconfig/tests/.coverage
        - python-codacy-coverage -r /tmp/cov-single.xml
        - bash <(curl -s https://codecov.io/bash) -Z -c -f /tmp/cov-single.xml
    - python: 3.7-dev
      env: TOXENV=py37
      os: linux
    - language: generic
      env: TOXENV=py27
      os: osx
    - language: generic
      env: TOXENV=py36
      os: osx

before_install:
- bash ./ci/travis_before_install.sh
install:
  - bash ./ci/travis_install.sh

script:
  - tox

which properly uploads the report to the server.