dict.py

from testutils import assertRaises

assert dict(a=2, b=3) == {'a': 2, 'b': 3}
assert dict({'a': 2, 'b': 3}, b=4) == {'a': 2, 'b': 4}
assert dict([('a', 2), ('b', 3)]) == {'a': 2, 'b': 3}

assert {} == {}
assert not {'a': 2} == {}
assert not {} == {'a': 2}
assert not {'b': 2} == {'a': 2}
assert not {'a': 4} == {'a': 2}
assert {'a': 2} == {'a': 2}

nan = float('nan')
assert {'a': nan} == {'a': nan}

a = {'g': 5}
b = {'a': a, 'd': 9}
c = dict(b)
c['d'] = 3
c['a']['g'] = 2
assert a == {'g': 2}
assert b == {'a': a, 'd': 9}

a.clear()
assert len(a) == 0

a = {'a': 5, 'b': 6}
res = set()
for value in a.values():
        res.add(value)
assert res == set([5,6])

count = 0
for (key, value) in a.items():
        assert a[key] == value
        count += 1
assert count == len(a)

res = set()
for key in a.keys():
        res.add(key)
assert res == set(['a','b'])

# Deleted values are correctly skipped over:
x = {'a': 1, 'b': 2, 'c': 3, 'd': 3}
del x['c']
it = iter(x.items())
assert ('a', 1) == next(it)
assert ('b', 2) == next(it)
assert ('d', 3) == next(it)
with assertRaises(StopIteration):
    next(it)

with assertRaises(KeyError) as cm:
    del x[10]
assert cm.exception.args[0] == 10

# Iterating a dictionary is just its keys:
assert ['a', 'b', 'd'] == list(x)

# Iterating view captures dictionary when iterated.
data = {1: 2, 3: 4}
items = data.items()
assert list(items) == [(1, 2), (3, 4)]
data[5] = 6
assert list(items) == [(1, 2), (3, 4), (5, 6)]

# Values can be changed during iteration.
data = {1: 2, 3: 4}
items = iter(data.items())
assert (1, 2) == next(items)
data[3] = "changed"
assert (3, "changed") == next(items)

# But we can't add or delete items during iteration.
d = {}
a = iter(d.items())
d['a'] = 2
b = iter(d.items())
assert ('a', 2) == next(b)
with assertRaises(RuntimeError):
    next(a)
del d['a']
with assertRaises(RuntimeError):
    next(b)

# View isn't itself an iterator.
with assertRaises(TypeError):
    next(data.keys())

assert len(data.keys()) == 2

x = {}
x[1] = 1
assert x[1] == 1

x[7] = 7
x[2] = 2
x[(5, 6)] = 5

with assertRaises(TypeError):
    x[[]] # Unhashable type.

x["here"] = "here"
assert x.get("not here", "default") == "default"
assert x.get("here", "default") == "here"
assert x.get("not here") == None

class LengthDict(dict):
    def __getitem__(self, k):
        return len(k)

x = LengthDict()
assert type(x) == LengthDict
assert x['word'] == 4
assert x.get('word') is None

assert 5 == eval("a + word", LengthDict())


class Squares(dict):
    def __missing__(self, k):
        v = k * k
        self[k] = v
        return v

x = Squares()
assert x[-5] == 25

# An object that hashes to the same value always, and compares equal if any its values match.
class Hashable(object):
    def __init__(self, *args):
        self.values = args
    def __hash__(self):
        return 1
    def __eq__(self, other):
        for x in self.values:
            for y in other.values:
                if x == y:
                    return True
        return False

x = {}
x[Hashable(1,2)] = 8

assert x[Hashable(1,2)] == 8
assert x[Hashable(3,1)] == 8

x[Hashable(8)] = 19
x[Hashable(19,8)] = 1
assert x[Hashable(8)] == 1
assert len(x) == 2

assert list({'a': 2, 'b': 10}) == ['a', 'b']
x = {}
x['a'] = 2
x['b'] = 10
assert list(x) == ['a', 'b']

y = x.copy()
x['c'] = 12
assert y == {'a': 2, 'b': 10}

y.update({'c': 19, "d": -1, 'b': 12})
assert y == {'a': 2, 'b': 12, 'c': 19, 'd': -1}

y.update(y)
assert y == {'a': 2, 'b': 12, 'c': 19, 'd': -1}  # hasn't changed

# KeyError has object that used as key as an .args[0]
with assertRaises(KeyError) as cm:
    x['not here']
assert cm.exception.args[0] == "not here"
with assertRaises(KeyError) as cm:
    x.pop('not here')
assert cm.exception.args[0] == "not here"

with assertRaises(KeyError) as cm:
    x[10]
assert cm.exception.args[0] == 10
with assertRaises(KeyError) as cm:
    x.pop(10)
assert cm.exception.args[0] == 10

class MyClass: pass
obj = MyClass()

with assertRaises(KeyError) as cm:
    x[obj]
assert cm.exception.args[0] == obj
with assertRaises(KeyError) as cm:
    x.pop(obj)
assert cm.exception.args[0] == obj

x = {1: 'a', '1': None}
assert x.pop(1) == 'a'
assert x.pop('1') is None
assert x == {}

x = {1: 'a'}
assert (1, 'a') == x.popitem()
assert x == {}
with assertRaises(KeyError) as cm:
    x.popitem()
assert cm.exception.args == ('popitem(): dictionary is empty',)

x = {'a': 4}
assert 4 == x.setdefault('a', 0)
assert x['a'] == 4
assert 0 == x.setdefault('b', 0)
assert x['b'] == 0
assert None == x.setdefault('c')
assert x['c'] is None

assert {1: None, "b": None} == dict.fromkeys([1, "b"])
assert {1: 0, "b": 0} == dict.fromkeys([1, "b"], 0)

x = {'a': 1, 'b': 1, 'c': 1}
y = {'b': 2, 'c': 2, 'd': 2}
z = {'c': 3, 'd': 3, 'e': 3}

w = {1: 1, **x, 2: 2, **y, 3: 3, **z, 4: 4}
assert w == {1: 1, 'a': 1, 'b': 2, 'c': 3, 2: 2, 'd': 3, 3: 3, 'e': 3, 4: 4}

assert str({True: True, 1.0: 1.0}) == str({True: 1.0})

class A:
    def __hash__(self):
        return 1
    def __eq__(self, other):
        return isinstance(other, A)
class B:
    def __hash__(self):
        return 1
    def __eq__(self, other):
        return isinstance(other, B)

s = {1: 0, A(): 1, B(): 2}
assert len(s) == 3
assert s[1] == 0
assert s[A()] == 1
assert s[B()] == 2