tox multiple tests, re-using tox environment

Question

Is it possible to do the following using a single tox virtual environment?

[tox]
envlist = test, pylint, flake8, mypy
skipsdist = true

[testenv:lint]
deps = pylint
commands = pylint .

[testenv:flake8]
deps = flake8
commands = flake8 .

[testenv:mypy]
commands = mypy . --strict

[testenv:test]
deps = pytest
commands = pytest

As I am only testing on my python version (py3.7), I don't want tox to have to create 4 environments ( .tox/test , .tox/pylint , .tox/flake8 , .tox/mypy ) when they could all be run on a single environment.

I also want to see what failed individually individually, thus don't want to do:

[tox]
skipsdist = true

[testenv]
commands = pylint .
           flake8 .
           mypy . --strict
           pytest

as the output would be like this:

_____________ summary ___________
ERROR:   python: commands failed

and not like this:

____________________summary _________________
ERROR:   test: commands failed
ERROR:   lint: commands failed
ERROR:   mypy: commands failed
  test: commands succeeded

Answer 1

Two approaches come to mind:

1. You can set them all to use the same envdir so that there's little work to be done when "building" the virtualenv for the test environments successively:

[testenv:lint]
envdir = {toxworkdir}/.work_env
deps = pylint
commands = pylint .

[testenv:flake8]
envdir = {toxworkdir}/.work_env
deps = flake8
commands = flake8 .

[testenv:mypy]
envdir = {toxworkdir}/.work_env
commands = mypy . --strict

[testenv:test]
envdir = {toxworkdir}/.work_env
deps = pytest
commands = pytest

2. This is really about the same, but using generative names and factor-specific commands to make it more concise (search the tox configuration doc page for those terms for more info). It also installs all of the deps up front:

[testenv:{lint,flake8,mypy,test}]
envdir = {toxworkdir}/.work_env
deps = pylint, flake8, pytest
commands =
    lint: pylint .
    flake8: flake8 .
    mypy: mypy . --strict
    test: pytest

Answer 2

tox stops at the first failed command. So my recommendation is to order commands from fasterst to slowest and allow tox to do the rest:

[testenv]
commands =
    flake8 .
    pylint .
    mypy . --strict
    pytest