Run flake8 via pre-commit for the pipenv lint script

Pre-commit is a nice wrapper for this particularily because it allows
both the snekbox and tests to be linted with a single command while
clearly distinguishing their results.

The Python script is a cross-platform implementation of the following:
    git ls-files -- '*.py' | xargs pre-commit run flake8 --files

1 files changed, 7 insertions, 1 deletions

diff --git a/Pipfile b/Pipfile
index 69bb0df..ea6299b 100644
--- a/Pipfile
+++ b/Pipfile
@@ -26,7 +26,13 @@ flake8-quotes = "*"
 python_version = "3.7"
 
 [scripts]
-lint = "flake8"
+lint = """
+python -c
+\"import subprocess, sys
+files = subprocess.check_output(('git', 'ls-files', '--', '*.py')).decode('UTF-8').strip()
+args = ['pre-commit', 'run', 'flake8', '--files'] + files.split('\\n')
+subprocess.run(args, stdout=sys.stdout, stderr=sys.stderr)\"
+"""
 precommit = "pre-commit install"
 test = "pytest tests --cov . --cov-report term-missing -v"
 report = "pytest tests --cov . --cov-report=html"