Move lint dependencies to extras_require (#8330)

Lint dependencies can now be installed with pip install -e ".[lint]"

This should help keep the version in sync between tox and documentation.

CONTRIBUTING.md

@@ -46,7 +46,7 @@ locally. You'll need python 3.6 or later, and to install a number of tools:
 
 ```
 # Install the dependencies
-pip install -U black flake8 flake8-comprehensions isort
+pip install -e ".[lint]"
 
 # Run the linter script
 ./scripts-dev/lint.sh

changelog.d/8330.misc

@@ -0,0 +1 @@
+Move lint-related dependencies to package-extra field, update CONTRIBUTING.md to utilise this.

synapse/python_dependencies.py

@@ -104,13 +104,16 @@ CONDITIONAL_REQUIREMENTS = {
     # hiredis is not a *strict* dependency, but it makes things much faster.
     # (if it is not installed, we fall back to slow code.)
     "redis": ["txredisapi>=1.4.7", "hiredis"],
+    # We pin black so that our tests don't start failing on new releases.
+    "lint": ["isort==5.0.3", "black==19.10b0", "flake8-comprehensions", "flake8"],
 }
 
 ALL_OPTIONAL_REQUIREMENTS = set()  # type: Set[str]
 
 for name, optional_deps in CONDITIONAL_REQUIREMENTS.items():
     # Exclude systemd as it's a system-based requirement.
-    if name not in ["systemd"]:
+    # Exclude lint as it's a dev-based requirement.
+    if name not in ["systemd", "lint"]:
         ALL_OPTIONAL_REQUIREMENTS = set(optional_deps) | ALL_OPTIONAL_REQUIREMENTS
 
 

tox.ini

@@ -118,20 +118,14 @@ commands =
     check-manifest
 
 [testenv:check_codestyle]
-skip_install = True
-deps =
-    flake8
-    flake8-comprehensions
-    # We pin so that our tests don't start failing on new releases of black.
-    black==19.10b0
+extras = lint
 commands =
     python -m black --check --diff .
     /bin/sh -c "flake8 synapse tests scripts scripts-dev contrib synctl {env:PEP8SUFFIX:}"
     {toxinidir}/scripts-dev/config-lint.sh
 
 [testenv:check_isort]
-skip_install = True
-deps = isort==5.0.3
+extras = lint
 commands = /bin/sh -c "isort -c --df --sp setup.cfg synapse tests scripts-dev scripts"
 
 [testenv:check-newsfragment]