cpython/Lib/test/test_support.py
Tim Peters 2f228e75e4 Get rid of the superstitious "~" in dict hashing's "i = (~hash) & mask".
The comment following used to say:
	/* We use ~hash instead of hash, as degenerate hash functions, such
	   as for ints <sigh>, can have lots of leading zeros. It's not
	   really a performance risk, but better safe than sorry.
	   12-Dec-00 tim:  so ~hash produces lots of leading ones instead --
	   what's the gain? */
That is, there was never a good reason for doing it.  And to the contrary,
as explained on Python-Dev last December, it tended to make the *sum*
(i + incr) & mask (which is the first table index examined in case of
collison) the same "too often" across distinct hashes.

Changing to the simpler "i = hash & mask" reduced the number of string-dict
collisions (== # number of times we go around the lookup for-loop) from about
6 million to 5 million during a full run of the test suite (these are
approximate because the test suite does some random stuff from run to run).
The number of collisions in non-string dicts also decreased, but not as
dramatically.

Note that this may, for a given dict, change the order (wrt previous
releases) of entries exposed by .keys(), .values() and .items().  A number
of std tests suffered bogus failures as a result.  For dicts keyed by
small ints, or (less so) by characters, the order is much more likely to be
in increasing order of key now; e.g.,

>>> d = {}
>>> for i in range(10):
...    d[i] = i
...
>>> d
{0: 0, 1: 1, 2: 2, 3: 3, 4: 4, 5: 5, 6: 6, 7: 7, 8: 8, 9: 9}
>>>

Unfortunately. people may latch on to that in small examples and draw a
bogus conclusion.

test_support.py
    Moved test_extcall's sortdict() into test_support, made it stronger,
    and imported sortdict into other std tests that needed it.
test_unicode.py
    Excluced cp875 from the "roundtrip over range(128)" test, because
    cp875 doesn't have a well-defined inverse for unicode("?", "cp875").
    See Python-Dev for excruciating details.
Cookie.py
    Chaged various output functions to sort dicts before building
    strings from them.
test_extcall
    Fiddled the expected-result file.  This remains sensitive to native
    dict ordering, because, e.g., if there are multiple errors in a
    keyword-arg dict (and test_extcall sets up many cases like that), the
    specific error Python complains about first depends on native dict
    ordering.
2001-05-13 00:19:31 +00:00

135 lines
3.3 KiB
Python

"""Supporting definitions for the Python regression test."""
import sys
class Error(Exception):
"""Base class for regression test exceptions."""
class TestFailed(Error):
"""Test failed."""
class TestSkipped(Error):
"""Test skipped.
This can be raised to indicate that a test was deliberatly
skipped, but not because a feature wasn't available. For
example, if some resource can't be used, such as the network
appears to be unavailable, this should be raised instead of
TestFailed.
"""
verbose = 1 # Flag set to 0 by regrtest.py
use_large_resources = 1 # Flag set to 0 by regrtest.py
def unload(name):
try:
del sys.modules[name]
except KeyError:
pass
def forget(modname):
unload(modname)
import os
for dirname in sys.path:
try:
os.unlink(os.path.join(dirname, modname + '.pyc'))
except os.error:
pass
FUZZ = 1e-6
def fcmp(x, y): # fuzzy comparison function
if type(x) == type(0.0) or type(y) == type(0.0):
try:
x, y = coerce(x, y)
fuzz = (abs(x) + abs(y)) * FUZZ
if abs(x-y) <= fuzz:
return 0
except:
pass
elif type(x) == type(y) and type(x) in (type(()), type([])):
for i in range(min(len(x), len(y))):
outcome = fcmp(x[i], y[i])
if outcome != 0:
return outcome
return cmp(len(x), len(y))
return cmp(x, y)
import os
# Filename used for testing
if os.name == 'java':
# Jython disallows @ in module names
TESTFN = '$test'
elif os.name != 'riscos':
TESTFN = '@test'
else:
TESTFN = 'test'
del os
from os import unlink
def findfile(file, here=__file__):
import os
if os.path.isabs(file):
return file
path = sys.path
path = [os.path.dirname(here)] + path
for dn in path:
fn = os.path.join(dn, file)
if os.path.exists(fn): return fn
return file
def verify(condition, reason='test failed'):
"""Verify that condition is true. If not, raise TestFailed.
The optional argument reason can be given to provide
a better error text.
"""
if not condition:
raise TestFailed(reason)
def sortdict(dict):
"Like repr(dict), but in sorted order."
items = dict.items()
items.sort()
reprpairs = ["%r: %r" % pair for pair in items]
withcommas = ", ".join(reprpairs)
return "{%s}" % withcommas
def check_syntax(statement):
try:
compile(statement, '<string>', 'exec')
except SyntaxError:
pass
else:
print 'Missing SyntaxError: "%s"' % statement
#=======================================================================
# Preliminary PyUNIT integration.
import unittest
class BasicTestRunner:
def run(self, test):
result = unittest.TestResult()
test(result)
return result
def run_unittest(testclass):
"""Run tests from a unittest.TestCase-derived class."""
if verbose:
runner = unittest.TextTestRunner(sys.stdout, verbosity=2)
else:
runner = BasicTestRunner()
suite = unittest.makeSuite(testclass)
result = runner.run(suite)
if not result.wasSuccessful():
raise TestFailed("errors occurred in %s.%s"
% (testclass.__module__, testclass.__name__))