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#!/usr/bin/env python
"""
Tests tightening preconditions... which should fail with an
InvalidPreconditionError
>>> b = Base()
>>> b.method(10)
90
>>> d = Derived()
>>> d.method(20)
200
>>> d.method(10)
Traceback (most recent call last):
...
PreconditionViolationError: ('testdbc9d.Derived.method', 6)
"""
from testdbc9b import Base
class Derived(Base):
def method(self, a):
"""We cannot tighten preconditions, we must only be able to loosen
them. Otherwise, abstract classes cannot work. The client thinks
they're calling with a particular contract and Surprise! it
doesn't work now.
pre: a > 10
"""
return a * 10
def _test():
import contract, doctest, testdbc9d
contract.checkmod(testdbc9d, contract.CHECK_ALL)
return doctest.testmod(testdbc9d)
if __name__ == '__main__':
t = _test()
if t[0]:
print "test: %d/%d failures" % t
else:
print "test: %d successes" % t[1]
b = Base()
b.method(10)
b.method(6)
d = Derived()
d.method(20)
d.method(10)
|
