Add runnable tasks for Python, starting with `unittest` from the
standard library. Both `TestCase`s (classes meant to be a unit of
testing) and individual test functions in a `TestCase` will have
runnable icons. For completeness, I also included a task that will run
`unittest` on the current file.
The implementation follows the `unittest` CLI. The unittest module can
be used from the command line to run tests from modules, classes or even
individual test methods:
```
python -m unittest test_module.TestClass
python -m unittest test_module.TestClass.test_method
```
```python
import unittest
class TestStringMethods(unittest.TestCase):
def test_upper(self):
self.assertEqual('foo'.upper(), 'FOO')
def test_isupper(self):
self.assertTrue('FOO'.isupper())
self.assertFalse('Foo'.isupper())
def test_split(self):
s = 'hello world'
self.assertEqual(s.split(), ['hello', 'world'])
# check that s.split fails when the separator is not a string
with self.assertRaises(TypeError):
s.split(2)
if __name__ == '__main__':
unittest.main()
```
From the snippet provided by `unittest` docs, a user may want to run
test_split independently of the other test functions in the test case.
Hence, I decided to make each test function runnable despite `TestCase`s
being the unit of testing.
## Example of running a `TestCase`
<img width="600" alt="image"
src="https://github.com/zed-industries/zed/assets/16619392/7be38b71-9d51-4b44-9840-f819502d600a">
## Example of running a test function in a `TestCase`
<img width="600" alt="image"
src="https://github.com/zed-industries/zed/assets/16619392/f0b6274c-4fa7-424e-a0f5-1dc723842046">
`unittest` will also run the `setUp` and `tearDown` fixtures.
Eventually, I want to add the more commonly used `pytest` runnables
(perhaps as an extension instead).
Release Notes:
- Added runnable tasks for Python `unittest`.
([#12080](https://github.com/zed-industries/zed/issues/12080)).
- Moves languages module from `zed` into a separate crate. That way we
have less of a long pole at the end of compilation.
- Removes moot dependencies on editor/picker. This is totally harmless
and might help in the future if we decide to decouple picker from
editor.
Before:
```
Number of crates that depend on 'picker' but not on 'editor': 1
Total number of crates that depend on 'picker': 13
Total number of crates that depend on 'editor': 30
```
After:
```
Number of crates that depend on 'picker' but not on 'editor': 5
Total number of crates that depend on 'picker': 12
Total number of crates that depend on 'editor': 26
```
The more crates depend on just picker but not editor, the better in that
case.
Release Notes:
- N/A
