def test_duck_attr_call():
"""
Should traverse the attributes and try to call them with the given
arguments, then return the result of the first successful call.
"""
obj = Obj(42)
duck = Duck(obj)
duck_calls = [
DuckCall(*p) for p in [
["foo"],
["bar", [3, 2]],
["baz", ["hello", "world"], {
"some_arg": 419
}],
]
]
assert duck.attr_call(*duck_calls) == obj.foo()
duck_calls = [
DuckCall(*p) for p in [
["non_existent_method_without_arguments"],
["non_existent_method_with_args", [1, 2, 3]],
["baz", ["hello", "world"], {
"some_arg": 419
}],
["foo"],
["bar", [3, 2]],
]
]
assert duck.attr_call(*duck_calls) == obj.baz("hello",
"world",
some_arg=419)
def test_duck_attr_default():
"""
Should return default value when none of the attributes is found
"""
obj = Obj(42)
duck = Duck(obj)
assert duck.attr("bad_property", "nope", default=12345426) == 12345426
def test_duck_call_default():
"""
Should return default value.
"""
obj = Obj(42)
duck = Duck(obj)
assert duck.call([["bad", "arguments"]], default=1234) == 1234
def test_duck_attr(attrs, expected):
"""
Should extract the first attribute present in obj
"""
obj = Obj(42)
duck = Duck(obj)
assert duck.attr(*attrs) == getattr(obj, expected)
def test_duck_get():
"""
Should return propery value
"""
obj = Obj(42)
duck = Duck(obj)
assert duck.attr_call(DuckGet("prop")) == obj.prop
def test_duck_call_raise():
"""
Should raise TypeError
"""
obj = Obj(42)
duck = Duck(obj)
with pytest.raises(TypeError):
duck.call([["bad", "arguments"]])
def test_duck_attr_call_fallback_property(duck_obj):
"""
If an argument is a string, attr_call interprets it a name of the property
to be returned.
"""
obj = Obj(42)
duck = Duck(obj)
assert duck.attr_call(DuckCall("non_existent"), "prop") == obj.prop
def test_duck_attr_raise():
"""
Should raise AttributeError when none of the attributes is found and
no default value given
"""
obj = Obj(42)
duck = Duck(obj)
with pytest.raises(AttributeError):
duck.attr("bad_property", "nope")
def test_duck_call():
"""
Should return the result of the first successful call the callable
object.
"""
obj = Obj(42)
duck = Duck(obj)
assert duck.call([["foo"]], [], [["hello1", "world1"]],
[["hello"], {
"argument2": "world"
}]) == obj("hello", argument2="world")
def test_duck_noargs_call():
"""
Should return the result of the first successful call the callable
object.
"""
def some_func():
return "hello!"
duck = Duck(some_func)
assert (duck.call([["foo"]], [], [["hello1", "world1"]],
[["hello"], {
"argument2": "world"
}]) == "hello!")
def test_duck_attr_call_raise():
"""
Should raise AttributeError if attribute is not present
and TypeError if the signature of the method is not compatible with
the arguments.
"""
obj = Obj(42)
duck = Duck(obj)
with pytest.raises(AttributeError):
assert duck.attr_call(DuckCall("non_existent"))
# OK method, bad signature
with pytest.raises(TypeError):
assert duck.attr_call(DuckCall("foo", ["bad", "arguments"]))
def duck_obj():
obj = Obj(42)
return Duck(obj), obj