Tox don't install tests_require in setup.py

I made my project with setuptools and I want to test it with tox. I listed deps in some variable and added to setup's parameter (tests_require and extras_require). My project need installing tests_require to test. But tox don't install them.

I tried this way. But it was not work.

install_command = pip install {opts} {packages}[tests]

How can I install test deps in tox without duplicated listing? (such as test_requirements.txt)