tests/printenv.py

check-code: catch Python 'is' comparing number or string literals

The Python 'is' operator compares object identity, so it should
definitely not be applied to string or number literals, which Python
implementations are free to represent with a temporary object.

This should catch the following kinds of bogus expressions (examples):

  x is 'foo'     x is not 'foo'
  x is "bar"     x is not "bar"
  x is 42        x is not 42
  x is -36       x is not -36

As originally proposed by Martin Geisler, amended with catching
negative numbers.

# simple script to be used in hooks
# copy it to the current directory when the test starts:
#
#     cp "$TESTDIR"/printenv.py .
#
# put something like this in the repo .hg/hgrc:
#
#     [hooks]
#     changegroup = python ../printenv.py <hookname> [exit] [output]
#
#   - <hookname> is a mandatory argument (e.g. "changegroup")
#   - [exit] is the exit code of the hook (default: 0)
#   - [output] is the name of the output file (default: use sys.stdout)
#              the file will be opened in append mode.
#
import os
import sys

try:
    import msvcrt
    msvcrt.setmode(sys.stdin.fileno(), os.O_BINARY)
    msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
    msvcrt.setmode(sys.stderr.fileno(), os.O_BINARY)
except ImportError:
    pass

exitcode = 0
out = sys.stdout

name = sys.argv[1]
if len(sys.argv) > 2:
    exitcode = int(sys.argv[2])
    if len(sys.argv) > 3:
        out = open(sys.argv[3], "ab")

# variables with empty values may not exist on all platforms, filter
# them now for portability sake.
env = [k for k, v in os.environ.iteritems()
       if k.startswith("HG_") and v]
env.sort()

# edit the variable part of the variable
url = os.environ.get("HG_URL", "")
if url.startswith("file:"):
    os.environ["HG_URL"] = "file:"
elif url.startswith("remote:http"):
    os.environ["HG_URL"] = "remote:http"

out.write("%s hook: " % name)
for v in env:
    out.write("%s=%s " % (v, os.environ[v]))
out.write("\n")
out.close()

sys.exit(exitcode)