Flake8 / pre-commit / nox review

.flake8

@@ -1,5 +1,5 @@
 [flake8]
-select = ANN,B,B9,BLK,C,E,F,RST,S,W
+select = B,B9,C,E,F,N,RST,S,W
 ignore = E203,E501,W503,C901,S308
 max-line-length = 80
 max-complexity = 10

.pre-commit-config.yaml

@@ -1,28 +1,51 @@
 repos:
-  - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v3.1.0
+  - repo: local
     hooks:
+      - id: black
+        name: black
+        entry: black
+        language: system
+        types: [python]
+        require_serial: true
+      - id: check-added-large-files
+        name: Check for added large files
+        entry: check-added-large-files
+        language: system
       - id: check-toml
+        name: Check Toml
+        entry: check-toml
+        language: system
+        types: [toml]
       - id: check-yaml
+        name: Check Yaml
+        entry: check-yaml
+        language: system
+        types: [yaml]
       - id: end-of-file-fixer
-      - id: trailing-whitespace
-      - id: check-added-large-files
-  - repo: https://github.com/psf/black
-    rev: 19.10b0
-    hooks:
-      - id: black
-  - repo: https://gitlab.com/pycqa/flake8
-    rev: 3.8.1
-    hooks:
+        name: Fix End of Files
+        entry: end-of-file-fixer
+        language: system
+        types: [text]
+        stages: [commit, push, manual]
       - id: flake8
-        additional_dependencies:
-          - flake8-bandit==2.1.2
-          - flake8-bugbear==20.1.4
-          - flake8-docstrings==1.5.0
-          - pep8-naming==0.10.0
-          - darglint==1.3.0
-  - repo: https://github.com/asottile/reorder_python_imports
-    rev: v2.3.0
-    hooks:
+        name: flake8
+        entry: flake8
+        language: system
+        types: [python]
+        require_serial: true
       - id: reorder-python-imports
+        name: Reorder python imports
+        entry: reorder-python-imports
+        language: system
+        types: [python]
         args: [--application-directories=src]
+      - id: trailing-whitespace
+        name: Trim Trailing Whitespace
+        entry: trailing-whitespace-fixer
+        language: system
+        types: [text]
+        stages: [commit, push, manual]
+  # - repo: https://github.com/prettier/prettier
+  #   rev: 2.0.5
+  #   hooks:
+  #     - id: prettier

noxfile.py

@@ -4,6 +4,7 @@
 import sys
 import tempfile
 from pathlib import Path
+from textwrap import dedent
 from typing import cast
 from typing import Iterator
 
@@ -109,12 +110,78 @@ def install(session: Session, *args: str) -> None:
         session.install(f"--constraint={requirements}", *args)
 
 
+def activate_virtualenv_in_precommit_hooks(session: Session) -> None:
+    """Activate virtualenv in hooks installed by pre-commit.
+
+    This function patches git hooks installed by pre-commit to activate the
+    session's virtual environment. This allows pre-commit to locate hooks in
+    that environment when invoked from git.
+
+    Args:
+        session: The Session object.
+    """
+    if session.bin is None:
+        return
+
+    virtualenv = session.env.get("VIRTUAL_ENV")
+    if virtualenv is None:
+        return
+
+    hookdir = Path(".git") / "hooks"
+    if not hookdir.is_dir():
+        return
+
+    for hook in hookdir.iterdir():
+        if hook.name.endswith(".sample") or not hook.is_file():
+            continue
+
+        text = hook.read_text()
+        bindir = repr(session.bin)[1:-1]  # strip quotes
+        if not (
+            Path("A") == Path("a") and bindir.lower() in text.lower() or bindir in text
+        ):
+            continue
+
+        lines = text.splitlines()
+        if not (lines[0].startswith("#!") and "python" in lines[0].lower()):
+            continue
+
+        header = dedent(
+            f"""\
+            import os
+            os.environ["VIRTUAL_ENV"] = {virtualenv!r}
+            os.environ["PATH"] = os.pathsep.join((
+                {session.bin!r},
+                os.environ.get("PATH", ""),
+            ))
+            """
+        )
+
+        lines.insert(1, header)
+        hook.write_text("\n".join(lines))
+
+
 @nox.session(name="pre-commit", python="3.8")
 def precommit(session: Session) -> None:
     """Lint using pre-commit."""
     args = session.posargs or ["run", "--all-files", "--show-diff-on-failure"]
-    install(session, "pre-commit")
+    install(
+        session,
+        "black",
+        "darglint",
+        "flake8",
+        "flake8-bandit",
+        "flake8-bugbear",
+        "flake8-docstrings",
+        "flake8-rst-docstrings",
+        "pep8-naming",
+        "pre-commit",
+        "pre-commit-hooks",
+        "reorder-python-imports",
+    )
     session.run("pre-commit", *args)
+    if args and args[0] == "install":
+        activate_virtualenv_in_precommit_hooks(session)
 
 
 @nox.session(python="3.8")