MAINT: rename 'py' environments in tox to 'tests' (#1626)

I decided to open this pull-request to rename the 'py*' environments to
'tests' in our `tox.ini` file. The reason is that this naming leads to a
lower confusion and a better syntax:

```diff
tox -e py310-fast-cov
tox -e tests-fast-cov
```

Also, the default environments are now `style, tests, docs`, which will
executed no matter the Python environment installed in the machine, as
long as it is a version supported by poliastro.

<!-- readthedocs-preview poliastro start -->
----
:books: Documentation preview :books::
https://poliastro--1626.org.readthedocs.build/en/1626/

<!-- readthedocs-preview poliastro end -->

.circleci/config.yml

@@ -2,6 +2,7 @@ version: 2.1
 
 jobs:
  quality: &test-template
+ description: Code style
  docker:
  - image: python:3.8
  environment:
@@ -13,83 +14,91 @@ jobs:
  - run: python -m pip install tox
  - run: tox
 
- py38-fast:
+ tests38-fast:
  <<: *test-template
+ description: Tests fast - Python 3.8
  environment:
- TOXENV: py38-fast
+ TOXENV: tests38-fast
 
- py38-online:
+ tests38-online:
  <<: *test-template
+ description: Tests online - Python 3.8
  environment:
- TOXENV: py38-online
+ TOXENV: tests38-online
 
- py38-slow:
+ tests38-slow:
  <<: *test-template
+ description: Tests slow - Python 3.8
  environment:
- TOXENV: py38-slow
+ TOXENV: tests38-slow
 
- py38-images:
+ tests38-images:
  <<: *test-template
+ description: Tests images - Python 3.8
  environment:
- TOXENV: py38-images
+ TOXENV: tests38-images
 
- py38-coverage:
+ tests38-coverage:
  <<: *test-template
+ description: Tests coverage - Python 3.8
  environment:
- TOXENV: py38-coverage
+ TOXENV: tests38-coverage
  steps:
  - checkout
  - run: python -m pip install tox
  - run: tox
  - run: python -m pip install codecov && codecov
 
- py39:
+ tests39:
  <<: *test-template
+ description: Tests - Python 3.9
  docker:
  - image: python:3.9
  environment:
- TOXENV: py39
+ TOXENV: tests39
 
- py310:
+ tests310:
  <<: *test-template
+ description: Tests - Python 3.10
  docker:
  - image: python:3.10
  environment:
- TOXENV: py310
+ TOXENV: tests310
 
- py311:
+ tests311:
  <<: *test-template
+ description: Tests - Python 3.11
  docker:
  - image: python:3.11
  environment:
- TOXENV: py311
+ TOXENV: tests311
 
 workflows:
  version: 2
  build_and_test:
  jobs:
  - quality
- - py38-fast:
+ - tests38-fast:
  requires:
  - quality
- - py38-online:
+ - tests38-online:
  requires:
  - quality
- - py38-slow:
+ - tests38-slow:
  requires:
  - quality
- - py38-images:
+ - tests38-images:
  requires:
  - quality
- - py38-coverage:
+ - tests38-coverage:
  requires:
  - quality
- - py39:
+ - tests39:
  requires:
  - quality
- - py310:
+ - tests310:
  requires:
  - quality
- - py311:
+ - tests311:
  requires:
  - quality

CONTRIBUTING.md

@@ -190,11 +190,11 @@ Apart from all the steps described above, you need to have these extra things in
 1. Add tests to your code. You have lots of examples in the `tests/` directory
  to get inspiration from. All new features and fixes should be tested,
  and in the ideal case the coverage rate should increase or stay the same.
-2. To check if your code is correct, run `tox -e reformat,check,py39-fast`
- (`py39` stands for Python 3.9, you can replace it by `py38`).
+2. To check if your code is correct, run `tox`. This command runs the code
+ style, the tests and build the documentation of the project.
 3. Notice that you can run a subset of the tests by
  passing extra arguments to pytest, for example running
- `tox -e py39-fast -- -k "anomaly"`
+ `tox -e tests-fast -- -k "anomaly"`
 
 Automatic services will ensure your code works
 on all the supported operating systems and Python versions.

tox.ini

@@ -2,7 +2,8 @@
 description = list of environments againts tox runs the tests
 envlist =
  style
- py3-fast
+ tests-fast
+ docs
 # See https://tox.readthedocs.io/en/latest/example/package.html#flit
 isolated_build = True
 isolated_build_env = build
@@ -14,11 +15,11 @@ whitelist_externals=
  /usr/bin/bash
 basepython =
  pypy3: pypy3
- py38: python3.8
- py39: python3.9
- py310: python3.10
- py311: python3.11
- {style,docs,reformat,build}: python3
+ tests38: python3.8
+ tests39: python3.9
+ tests310: python3.10
+ tests311: python3.11
+ {style,tests,docs,build}: python3
 setenv =
  PYTHONUNBUFFERED = yes
  PIP_PREFER_BINARY = 1