view tests/hypothesishelpers.py @ 28450:155e3308289c

hgext: officially turn 'hgext' into a namespace package

Actually since Python 2.3, there is some way to turn top level package into
"namespace package" so that multiple subpackage installed in different part of
the path can still be imported transparently. This feature was previously
thought (at least by myself) to be only provided by some setuptool black magic.

Turning hgext into such namespace package allows third extensions to install
themselves inside the "hgext" namespace package to avoid polluting the global
python module namespace. They will now be able to do so without making it a pain
to use a Mercurial "installed" in a different way/location than these
extensions.

The only constrains is that the extension ship a 'hgext/__init__.py' containing
the same call to 'pkgutil.extend_path' and nothing else. This seems realistic.

The main question that remains is: should we introduce a dedicated namespace for
third party extension (hgext3rd?) to make a clearer distinction between what is
officially supported and what is not? If so, this will be introduced in a follow
up patch.

# Helper module to use the Hypothesis tool in tests
#
# Copyright 2015 David R. MacIver
#
# For details see http://hypothesis.readthedocs.org

import os
import sys
import traceback

try:
    # hypothesis 2.x
    from hypothesis.configuration import set_hypothesis_home_dir
    from hypothesis import settings
except ImportError:
    # hypothesis 1.x
    from hypothesis.settings import set_hypothesis_home_dir
    from hypothesis import Settings as settings
import hypothesis.strategies as st
from hypothesis import given

# hypothesis store data regarding generate example and code
set_hypothesis_home_dir(os.path.join(
    os.getenv('TESTTMP'), ".hypothesis"
))

def check(*args, **kwargs):
    """decorator to make a function a hypothesis test

    Decorated function are run immediately (to be used doctest style)"""
    def accept(f):
        # Workaround for https://github.com/DRMacIver/hypothesis/issues/206
        # Fixed in version 1.13 (released 2015 october 29th)
        f.__module__ = '__anon__'
        try:
            with settings(max_examples=2000):
                given(*args, **kwargs)(f)()
        except Exception:
            traceback.print_exc(file=sys.stdout)
            sys.exit(1)
    return accept


def roundtrips(data, decode, encode):
    """helper to tests function that must do proper encode/decode roundtripping
    """
    @given(data)
    def testroundtrips(value):
        encoded = encode(value)
        decoded = decode(encoded)
        if decoded != value:
            raise ValueError(
                "Round trip failed: %s(%r) -> %s(%r) -> %r" % (
                    encode.__name__, value, decode.__name__, encoded,
                    decoded
                ))
    try:
        testroundtrips()
    except Exception:
        # heredoc swallow traceback, we work around it
        traceback.print_exc(file=sys.stdout)
        raise
    print("Round trip OK")


# strategy for generating bytestring that might be an issue for Mercurial
bytestrings = (
    st.builds(lambda s, e: s.encode(e), st.text(), st.sampled_from([
        'utf-8', 'utf-16',
    ]))) | st.binary()