Check if improvements are needed for test_requirements.txt setup

[merelcht]

Check if any of the below is still needed now we've implemented the pyproject.toml setup + datasets are removed:

• Try and figure out a nicer way of installing all the dependencies listed in the setup.py file rather than needing to maintain a separate test_requirements.txt file there -> test_requirements.txt doesn't exist anymore. Instead of this do:
  • Remove setup.py.
• Clean up kedro's test requirements to remove requirements for datasets that aren't needed any more

[sbrugman]

test could be another extras_require. The tests_require now used in setup.py seem not to be part of the pyproject.toml metadata ([ref]), so this move would be a step in that direction (#1724).

[deepyaman]

test could be another extras_require. The tests_require now used in setup.py seem not to be part of the pyproject.toml metadata ([ref]), so this move would be a step in that direction (#1724).

+1 on this approach; some packaging frameworks (like flit) have this special test extra (which I guess lends credibility to the approach?), and I've also used it on some other projects personally.

[astrojuanlu]

Note that in #2475 tests_requires was removed, there's only test_requirements.txt. #2152 was partially addressed, so at least now even if there's a setup.py for some dynamic stuff, most of the metadata is in pyproject.toml. We could definitely add another optional-dependencies group (former "extras").

[astrojuanlu]

Reopening, still some work to be done

[merelcht]

Completed in #3144 and #3143