extras.py

...
tests_requires = [
    'flake8>=2.4.1',
    'pytest>=2.9.1',
    'freezegun>=0.3.6',
    'coverage>=4.0',
]
devel_requires = test_requires + ['detox']
docs_requires = [
    'Sphinx==1.4',
    'sphinxcontrib-programoutput==0.8',
]
release_requires = docs_requires + [
    'wheel',
    'twine',
    'bumpversion',
]

setup(
    ...
    extras_require={
        'tests': test_requires,
        'devel': devel_requires,
        'docs': docs_requires,
        'release': release_requires,
    },
    ...
)

Now you can do

pip install -e .[devel] for a dev env.
pip install -e .[tests] for your tox/travis envs,
pip install -e .[release] when you want to publish