.git-pre-commit

#!/usr/bin/env python

# Copyright (c) 2009 Giampaolo Rodola'. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""
This gets executed on 'git commit' and rejects the commit in case the
submitted code does not pass validation. Validation is run only against
the *.py files which were modified in the commit. Checks:

- assert no space at EOLs
- assert not pdb.set_trace in code
- assert no bare except clause ("except:") in code
- assert "flake8" returns no warnings

Install this with "make install-git-hooks".
"""

from __future__ import print_function
import os
import subprocess
import sys


def term_supports_colors():
    try:
        import curses
        assert sys.stderr.isatty()
        curses.setupterm()
        assert curses.tigetnum("colors") > 0
    except Exception:
        return False
    else:
        return True


def hilite(s, ok=True, bold=False):
    """Return an highlighted version of 'string'."""
    if not term_supports_colors():
        return s
    attr = []
    if ok is None:  # no color
        pass
    elif ok:   # green
        attr.append('32')
    else:   # red
        attr.append('31')
    if bold:
        attr.append('1')
    return '\x1b[%sm%s\x1b[0m' % (';'.join(attr), s)


def exit(msg):
    msg = hilite(msg, ok=False)
    print(msg, file=sys.stderr)
    sys.exit(1)


def sh(cmd):
    """run cmd in a subprocess and return its output.
    raises RuntimeError on error.
    """
    p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE,
                         stderr=subprocess.PIPE, universal_newlines=True)
    stdout, stderr = p.communicate()
    if p.returncode != 0:
        raise RuntimeError(stderr)
    if stderr:
        print(stderr, file=sys.stderr)
    if stdout.endswith('\n'):
        stdout = stdout[:-1]
    return stdout


def main():
    out = sh("git diff --cached --name-only")
    py_files = [x for x in out.split(b'\n') if x.endswith(b'.py') and
                os.path.exists(x)]

    lineno = 0
    for path in py_files:
        with open(path) as f:
            for line in f:
                lineno += 1
                # space at end of line
                if line.endswith(' '):
                    print("%s:%s %r" % (path, lineno, line))
                    return exit(
                        "commit aborted: space at end of line")
                line = line.rstrip()
                # pdb
                if "pdb.set_trace" in line:
                    print("%s:%s %s" % (path, lineno, line))
                    return exit(
                        "commit aborted: you forgot a pdb in your python code")
                # bare except clause
                if "except:" in line and not line.endswith("# NOQA"):
                    print("%s:%s %s" % (path, lineno, line))
                    return exit("commit aborted: bare except clause")

    # flake8
    if py_files:
        try:
            import flake8  # NOQA
        except ImportError:
            return exit("commit aborted: flake8 is not installed; "
                        "run 'make setup-dev-env'")

        # XXX: we should scape spaces and possibly other amenities here
        ret = subprocess.call(
            "%s -m flake8 %s" % (sys.executable, " ".join(py_files)),
            shell=True)
        if ret != 0:
            return exit("commit aborted: python code is not flake8 compliant")


main()