Viewing file:  test_decorators.py (8.77 KB) -rw-r--r--
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import unittest
from test import test_support
def funcattrs(**kwds):
def decorate(func):
func.__dict__.update(kwds)
return func
return decorate
class MiscDecorators (object):
@staticmethod
def author(name):
def decorate(func):
func.__dict__['author'] = name
return func
return decorate
# -----------------------------------------------
class DbcheckError (Exception):
def __init__(self, exprstr, func, args, kwds):
# A real version of this would set attributes here
Exception.__init__(self, "dbcheck %r failed (func=%s args=%s kwds=%s)" %
(exprstr, func, args, kwds))
def dbcheck(exprstr, globals=None, locals=None):
"Decorator to implement debugging assertions"
def decorate(func):
expr = compile(exprstr, "dbcheck-%s" % func.func_name, "eval")
def check(*args, **kwds):
if not eval(expr, globals, locals):
raise DbcheckError(exprstr, func, args, kwds)
return func(*args, **kwds)
return check
return decorate
# -----------------------------------------------
def countcalls(counts):
"Decorator to count calls to a function"
def decorate(func):
func_name = func.func_name
counts[func_name] = 0
def call(*args, **kwds):
counts[func_name] += 1
return func(*args, **kwds)
call.func_name = func_name
return call
return decorate
# -----------------------------------------------
def memoize(func):
saved = {}
def call(*args):
try:
return saved[args]
except KeyError:
res = func(*args)
saved[args] = res
return res
except TypeError:
# Unhashable argument
return func(*args)
call.func_name = func.func_name
return call
# -----------------------------------------------
class TestDecorators(unittest.TestCase):
def test_single(self):
class C(object):
@staticmethod
def foo(): return 42
self.assertEqual(C.foo(), 42)
self.assertEqual(C().foo(), 42)
def test_staticmethod_function(self):
@staticmethod
def notamethod(x):
return x
self.assertRaises(TypeError, notamethod, 1)
def test_dotted(self):
decorators = MiscDecorators()
@decorators.author('Cleese')
def foo(): return 42
self.assertEqual(foo(), 42)
self.assertEqual(foo.author, 'Cleese')
def test_argforms(self):
# A few tests of argument passing, as we use restricted form
# of expressions for decorators.
def noteargs(*args, **kwds):
def decorate(func):
setattr(func, 'dbval', (args, kwds))
return func
return decorate
args = ( 'Now', 'is', 'the', 'time' )
kwds = dict(one=1, two=2)
@noteargs(*args, **kwds)
def f1(): return 42
self.assertEqual(f1(), 42)
self.assertEqual(f1.dbval, (args, kwds))
@noteargs('terry', 'gilliam', eric='idle', john='cleese')
def f2(): return 84
self.assertEqual(f2(), 84)
self.assertEqual(f2.dbval, (('terry', 'gilliam'),
dict(eric='idle', john='cleese')))
@noteargs(1, 2,)
def f3(): pass
self.assertEqual(f3.dbval, ((1, 2), {}))
def test_dbcheck(self):
@dbcheck('args[1] is not None')
def f(a, b):
return a + b
self.assertEqual(f(1, 2), 3)
self.assertRaises(DbcheckError, f, 1, None)
def test_memoize(self):
counts = {}
@memoize
@countcalls(counts)
def double(x):
return x * 2
self.assertEqual(double.func_name, 'double')
self.assertEqual(counts, dict(double=0))
# Only the first call with a given argument bumps the call count:
#
self.assertEqual(double(2), 4)
self.assertEqual(counts['double'], 1)
self.assertEqual(double(2), 4)
self.assertEqual(counts['double'], 1)
self.assertEqual(double(3), 6)
self.assertEqual(counts['double'], 2)
# Unhashable arguments do not get memoized:
#
self.assertEqual(double([10]), [10, 10])
self.assertEqual(counts['double'], 3)
self.assertEqual(double([10]), [10, 10])
self.assertEqual(counts['double'], 4)
def test_errors(self):
# Test syntax restrictions - these are all compile-time errors:
#
for expr in [ "1+2", "x[3]", "(1, 2)" ]:
# Sanity check: is expr is a valid expression by itself?
compile(expr, "testexpr", "exec")
codestr = "@%s\ndef f(): pass" % expr
self.assertRaises(SyntaxError, compile, codestr, "test", "exec")
# You can't put multiple decorators on a single line:
#
self.assertRaises(SyntaxError, compile,
"@f1 @f2\ndef f(): pass", "test", "exec")
# Test runtime errors
def unimp(func):
raise NotImplementedError
context = dict(nullval=None, unimp=unimp)
for expr, exc in [ ("undef", NameError),
("nullval", TypeError),
("nullval.attr", AttributeError),
("unimp", NotImplementedError)]:
codestr = "@%s\ndef f(): pass\nassert f() is None" % expr
code = compile(codestr, "test", "exec")
self.assertRaises(exc, eval, code, context)
def test_double(self):
class C(object):
@funcattrs(abc=1, xyz="haha")
@funcattrs(booh=42)
def foo(self): return 42
self.assertEqual(C().foo(), 42)
self.assertEqual(C.foo.abc, 1)
self.assertEqual(C.foo.xyz, "haha")
self.assertEqual(C.foo.booh, 42)
def test_order(self):
# Test that decorators are applied in the proper order to the function
# they are decorating.
def callnum(num):
"""Decorator factory that returns a decorator that replaces the
passed-in function with one that returns the value of 'num'"""
def deco(func):
return lambda: num
return deco
@callnum(2)
@callnum(1)
def foo(): return 42
self.assertEqual(foo(), 2,
"Application order of decorators is incorrect")
def test_eval_order(self):
# Evaluating a decorated function involves four steps for each
# decorator-maker (the function that returns a decorator):
#
# 1: Evaluate the decorator-maker name
# 2: Evaluate the decorator-maker arguments (if any)
# 3: Call the decorator-maker to make a decorator
# 4: Call the decorator
#
# When there are multiple decorators, these steps should be
# performed in the above order for each decorator, but we should
# iterate through the decorators in the reverse of the order they
# appear in the source.
actions = []
def make_decorator(tag):
actions.append('makedec' + tag)
def decorate(func):
actions.append('calldec' + tag)
return func
return decorate
class NameLookupTracer (object):
def __init__(self, index):
self.index = index
def __getattr__(self, fname):
if fname == 'make_decorator':
opname, res = ('evalname', make_decorator)
elif fname == 'arg':
opname, res = ('evalargs', str(self.index))
else:
assert False, "Unknown attrname %s" % fname
actions.append('%s%d' % (opname, self.index))
return res
c1, c2, c3 = map(NameLookupTracer, [ 1, 2, 3 ])
expected_actions = [ 'evalname1', 'evalargs1', 'makedec1',
'evalname2', 'evalargs2', 'makedec2',
'evalname3', 'evalargs3', 'makedec3',
'calldec3', 'calldec2', 'calldec1' ]
actions = []
@c1.make_decorator(c1.arg)
@c2.make_decorator(c2.arg)
@c3.make_decorator(c3.arg)
def foo(): return 42
self.assertEqual(foo(), 42)
self.assertEqual(actions, expected_actions)
# Test the equivalence claim in chapter 7 of the reference manual.
#
actions = []
def bar(): return 42
bar = c1.make_decorator(c1.arg)(c2.make_decorator(c2.arg)(c3.make_decorator(c3.arg)(bar)))
self.assertEqual(bar(), 42)
self.assertEqual(actions, expected_actions)
def test_main():
test_support.run_unittest(TestDecorators)
if __name__=="__main__":
test_main()
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