Drop support for parsing Python 2 (#3933)

[etc/vim.git] / docs / contributing / the_basics.md

diff --git a/docs/contributing/the_basics.md b/docs/contributing/the_basics.md
index 9325a9e44edc83dcd0b879601812b188ce962219..864894b491fbe3cdaca802911d952cc2a5530c17 100644 (file)
--- a/docs/contributing/the_basics.md
+++ b/docs/contributing/the_basics.md
@@ -4,15 +4,17 @@ An overview on contributing to the _Black_ project.
 
 ## Technicalities
 
-Development on the latest version of Python is preferred. As of this writing it's 3.9.
-You can use any operating system.
+Development on the latest version of Python is preferred. You can use any operating
+system.
 
 Install development dependencies inside a virtual environment of your choice, for
 example:
 
 ```console
 $ python3 -m venv .venv
-$ source .venv/bin/activate
+$ source .venv/bin/activate # activation for linux and mac
+$ .venv\Scripts\activate # activation for windows
+
 (.venv)$ pip install -r test_requirements.txt
 (.venv)$ pip install -e .[d]
 (.venv)$ pre-commit install
@@ -30,8 +32,49 @@ the root of the black repo:
 
 # Optional Fuzz testing
 (.venv)$ tox -e fuzz
+
+# Format Black itself
+(.venv)$ tox -e run_self
 ```
 
+### Development
+
+Further examples of invoking the tests
+
+```console
+# Run all of the above mentioned, in parallel
+(.venv)$ tox --parallel=auto
+
+# Run tests on a specific python version
+(.venv)$ tox -e py39
+
+# pass arguments to pytest
+(.venv)$ tox -e py -- --no-cov
+
+# print full tree diff, see documentation below
+(.venv)$ tox -e py -- --print-full-tree
+
+# disable diff printing, see documentation below
+(.venv)$ tox -e py -- --print-tree-diff=False
+```
+
+`Black` has two pytest command-line options affecting test files in `tests/data/` that
+are split into an input part, and an output part, separated by a line with`# output`.
+These can be passed to `pytest` through `tox`, or directly into pytest if not using
+`tox`.
+
+#### `--print-full-tree`
+
+Upon a failing test, print the full concrete syntax tree (CST) as it is after processing
+the input ("actual"), and the tree that's yielded after parsing the output ("expected").
+Note that a test can fail with different output with the same CST. This used to be the
+default, but now defaults to `False`.
+
+#### `--print-tree-diff`
+
+Upon a failing test, print the diff of the trees as described above. This is the
+default. To turn it off pass `--print-tree-diff=False`.
+
 ### News / Changelog Requirement
 
 `Black` has CI that will check for an entry corresponding to your PR in `CHANGES.md`. If
@@ -62,7 +105,7 @@ If you make changes to docs, you can test they still build locally too.
 
 ```console
 (.venv)$ pip install -r docs/requirements.txt
-(.venv)$ pip install [-e] .[d]
+(.venv)$ pip install -e .[d]
 (.venv)$ sphinx-build -a -b html -W docs/ docs/_build/
 ```