.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.

"""
This gets executed on 'git commit' and emits a warning 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 warn(msg):
    msg = hilite("warn: " + msg, ok=False)
    print(msg, file=sys.stderr)


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('\n') if x.endswith('.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 warn("space at end of line")
                line = line.rstrip()
                # pdb
                if "pdb.set_trace" in line:
                    print("%s:%s %s" % (path, lineno, line))
                    return warn("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 warn("bare except clause")

    # flake8
    if py_files:
        try:
            import flake8  # NOQA
        except ImportError:
            return warn("flake8 is not installed; run 'make pydeps'")

        # 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 warn("python code is not flake8 compliant")


main()