Update Tox settings for easier use & better performance

CONTRIBUTING.md

@@ -10,19 +10,19 @@ this case, the [Apache Software License v2](LICENSE).
 
 To contribute to Sygnal, ensure you have Python 3.7 or newer and then run:
 
-```
+```bash
 python3 -m venv venv
 ./venv/bin/pip install -e .
 ./venv/bin/pip install -U black flake8 isort mypy mypy-zope tox
 ```
 
 This creates an isolated virtual Python environment ("virtualenv") just for
 use with Sygnal, then installs Sygnal along with its dependencies, and lastly
-installs a handful of useful tools 
+installs a handful of useful tools
 
 Finally, activate the virtualenv by running:
 
-```
+```bash
 source ./venv/bin/activate
 ```
 
@@ -37,7 +37,7 @@ the virtualenv.
 
 To make sure everything is working as expected, run the unit tests:
 
-```
+```bash
 tox -e py
 ```
 
@@ -88,27 +88,23 @@ Sygnal follows the [Synapse code style].
 Many of the conventions are enforced by scripts which are run as part of the
 [continuous integration system](#continuous-integration-and-testing).
 
-To help check and fix adherence to the code style, you can run `scripts-dev/lint.sh`
-locally. You'll need Python 3.7 or later, and to install a number of tools:
-
-```
-# Install the dependencies
-pip install -U black flake8 isort mypy mypy-zope
-
-# Run the linter script
-./scripts-dev/lint.sh
-```
+To help check and fix adherence to the code style, you can run `tox`
+locally. You'll need Python 3.7 or later, and a virtual environment configured and
+active:
 
-**Note that the script does not just test/check, but also reformats code, so you
-may wish to ensure any new code is committed first**.
+```bash
+# Activate the virtual environment
+source ./venv/bin/activate
 
-By default, this script checks all files and can take some time; if you alter
-only certain files, you might wish to specify paths as arguments to reduce the
-run-time:
+# Run the code style check
+tox -e check_codestyle
 
+# Run the types check
+tox -e check_types
 ```
-./scripts-dev/lint.sh path/to/file1.py path/to/file2.py path/to/folder
-```
+
+These commands will consider the paths and files related to the project (i.e.
+everything in `sygnal/` and in `tests/` as well as the `setup.py` file).
 
 Before pushing new changes, ensure they don't produce linting errors. Commit any
 files that were corrected.

changelog.d/193.doc

@@ -0,0 +1 @@
+Update CONTRIBUTING.md to specify how to run code style and type checks with Tox, and add formatting to code block samples.

changelog.d/193.misc

@@ -0,0 +1 @@
+Updated Tox to run in the installed version of Python (instead of specifying Python 3.7) and to consider specific paths and folders while running checks, instead of the whole repository (potentially including unwanted files and folders, e.g. the virtual environment).

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py37, check_codestyle, check_types
+envlist = py, check_codestyle, check_types
 
 [testenv]
 
@@ -22,13 +22,13 @@ deps =
   black==19.10b0
   isort~=5.0
 commands =
-  flake8 .
-  black --check --diff .
-  isort --check-only --diff .
+  flake8 sygnal/ tests/ setup.py
+  black --check --diff sygnal/ tests/ setup.py
+  isort --check-only --diff sygnal/ tests/ setup.py
 
 [testenv:check_types]
 deps =
   mypy==0.780
   mypy-zope==0.2.7
 commands =
-  mypy .
+  mypy sygnal/ tests/ setup.py