Deprecate the support for "python setup.py test"

[zhouzaida]

Thanks for your contribution and we appreciate it a lot. The following instructions would make your pull request more healthy and more easily get feedback. If you do not understand some items, don't worry, just make the pull request and seek help from maintainers.

Motivation

Deprecate the support for "python setup.py test" by removing the setup_requires and tests_require options from setup.py.

• The reason why we deprecate the support for "python setup.py test" can be found at Deprecate test command pypa/setuptools#1684.

You're welcome to consider that. The biggest issue with setup.py test now is that it relies on easy_install and setup_requires, both of which are superseded by pip and PEP 517. Another issue is that setup.py test has no mechanism to specify the version of setuptools under which to run... dependencies need to be resolved before setup.py is invoked. Any tools that attempts to use setuptools plugins to run tests will be forever be responsible to ensure the requisite version of setuptools is installed in advance (it's too late by the time setuptools is imported).

• The reason why we remove them can be found at https://pypi.org/project/pytest-runner/#description

pytest-runner depends on deprecated features of setuptools and relies on features that break security mechanisms in pip. For example ‘setup_requires’ and ‘tests_require’ bypass pip --require-hashes. See also pypa/setuptools#1684.
It is recommended that you:

• Remove 'pytest-runner' from your setup_requires, preferably removing the setup_requires option.
• Remove 'pytest' and any other testing requirements from tests_require, preferably removing the tests_requires option.
• Select a tool to bootstrap and then run tests such as tox.

Modification

• Update the setup.py

BC-breaking (Optional)

Does the modification introduce changes that break the backward-compatibility of the downstream repositories?
If so, please describe how it breaks the compatibility and how the downstream projects should modify their code to keep compatibility with this PR.

Use cases (Optional)

If this PR introduces a new feature, it is better to list some use cases here, and update the documentation.

Checklist

Before PR:

• I have read and followed the workflow indicated in the CONTRIBUTING.md to create this PR.
• Pre-commit or linting tools indicated in CONTRIBUTING.md are used to fix the potential lint issues.
• Bug fixes are covered by unit tests, the case that causes the bug should be added in the unit tests.
• New functionalities are covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• The documentation has been modified accordingly, including docstring or example tutorials.

After PR:

• If the modification has potential influence on downstream or other related projects, this PR should be tested with some of those projects, like MMDet or MMCls.
• CLA has been signed and all committers have signed the CLA in this PR.