pre-commit isort and black --check only for cirrus-ci

.cirrus.yml

@@ -34,7 +34,7 @@ env:
   # Increment the build number to force new pip cache upload.
   PIP_CACHE_BUILD: "0"
   # Pip packages to be upgraded/installed.
-  PIP_CACHE_PACKAGES: "nox pip setuptools wheel"
+  PIP_CACHE_PACKAGES: "nox pip pyyaml setuptools wheel"
   # Conda packages to be installed.
   CONDA_CACHE_PACKAGES: "nox pip"
   # Git commit hash for iris test data.

.pre-commit-config.yaml

@@ -32,7 +32,7 @@ repos:
     hooks:
     -   id: black
         pass_filenames: false
-        args: [--config=./pyproject.toml, --check, .]
+        args: [--config=./pyproject.toml, .]
 
 -   repo: https://github.com/PyCQA/flake8
     rev: 3.9.2
@@ -46,7 +46,7 @@ repos:
     hooks:
     -   id: isort
         types: [file, python]
-        args: [--filter-files, --check]
+        args: [--filter-files]
 
 -   repo: https://github.com/asottile/blacken-docs
     rev: v1.10.0

noxfile.py

@@ -173,13 +173,28 @@ def lint(session: nox.sessions.Session):
         A `nox.sessions.Session` object.
 
     """
+    import yaml
+
     # Pip install the session requirements.
     session.install("pre-commit")
-    # Execute the pre-commit linting tasks.
-    cmd = ["pre-commit", "run", "--all-files"]
-    hooks = ["black", "blacken-docs", "flake8", "isort"]
-    for hook in hooks:
-        session.run(*cmd, hook)
+
+    # Load the pre-commit configuration YAML file.
+    with open(".pre-commit-config.yaml", "r") as fi:
+        config = yaml.load(fi, Loader=yaml.FullLoader)
+
+    # Enumerate the ids of pre-commit hooks we want to run.
+    # We're only capturing the hook id of pre-commit repos with *one*
+    # registered hook. This is a simple approach to filtering out
+    # the "https://github.com/pre-commit/pre-commit-hooks" hooks,
+    # all of which we don't want to run within nox.
+    ids = [
+        entry["hooks"][0]["id"]
+        for entry in config["repos"]
+        if len(entry["hooks"]) == 1
+    ]
+
+    # Execute the pre-commit linting hooks.
+    [session.run("pre-commit", "run", "--all-files", id) for id in ids]
 
 
 @nox.session(python=PY_VER, venv_backend="conda")