from test
.test_support
import TestFailed
# A test for SF bug 422177: manifest float constants varied way too much in
# precision depending on whether Python was loading a module for the first
# time, or reloading it from a precompiled .pyc. The "expected" failure
# mode is that when test_import imports this after all .pyc files have been
# erased, it passes, but when test_import imports this from
# double_const.pyc, it fails. This indicates a woeful loss of precision in
# the marshal format for doubles. It's also possible that repr() doesn't
# produce enough digits to get reasonable precision for this box.
TWOPI
= 6.28318530717958648
PI_str
= "3.14159265358979324"
TWOPI_str
= "6.28318530717958648"
# Verify that the double x is within a few bits of eval(x_str).
# If diff is no larger than 3 ULP (wrt x2), then diff/8 is no larger
# than 0.375 ULP, so adding diff/8 to x2 should have no effect.
if x2
+ (diff
/ 8.) != x2
:
raise TestFailed("Manifest const %s lost too much precision " % x_str
)
check_ok(TWOPI
, TWOPI_str
)