def test_fromkeys(self): self.assertEqual(dict.fromkeys('abc'), {'a':None, 'b':None, 'c':None}) d = dict() self.assertIsNot(d.fromkeys('abc'), d) self.assertEqual(d.fromkeys('abc'), {'a':None, 'b':None, 'c':None}) self.assertEqual(d.fromkeys((4,5),0), {4:0, 5:0}) self.assertEqual(d.fromkeys([]), {}) def g(): yield 1 self.assertEqual(d.fromkeys(g()), {1:None}) self.assertRaises(TypeError, dict().fromkeys, 3) class dictlike(dict): pass self.assertEqual(dictlike.fromkeys('a'), {'a':None}) self.assertEqual(dictlike().fromkeys('a'), {'a':None}) self.assertIsInstance(dictlike.fromkeys('a'), dictlike) self.assertIsInstance(dictlike().fromkeys('a'), dictlike) # class mydict(dict): # def __new__(cls): # return UserDict.UserDict() # ud = mydict.fromkeys('ab') # self.assertEqual(ud, {'a':None, 'b':None}) # self.assertIsInstance(ud, UserDict.UserDict) # self.assertRaises(TypeError, dict.fromkeys) class Exc(Exception): pass class baddict1(dict): def __init__(self): raise Exc() self.assertRaises(Exc, baddict1.fromkeys, [1]) @implements_iterator class BadSeq(object): def __iter__(self): return self def __next__(self): raise Exc() self.assertRaises(Exc, dict.fromkeys, BadSeq()) class baddict2(dict): def __setitem__(self, key, value): raise Exc() self.assertRaises(Exc, baddict2.fromkeys, [1]) # test fast path for dictionary inputs d = dict(zip(range(6), range(6))) self.assertEqual(dict.fromkeys(d, 0), dict(zip(range(6), [0]*6))) class baddict3(dict): def __new__(cls): return d d = dict((i, i) for i in range(10)) res = d.copy() res.update(a=None, b=None, c=None)