assert dir() == ["__builtins__", "__doc__", "__name__"]

import os
assert "write" in dir(os)

assert "__add__" in dir(int)
assert "mro" not in dir(int)

class Foo(object):
    def __init__(self):
        self.x = 17
        self.y = "blah"
        self.z = 8.2

x = Foo()
assert "x" in dir(x)           # instance
assert "y" in dir(x)           # instance
assert "z" in dir(x)           # instance
assert "__init__" in dir(x)    # class
assert "__getitem__" in dir(x) # bases

class CustomDir(object):
    def __dir__(self):
        return ["kan", "ga", "roo"]

x = CustomDir()
assert dir(x) == ["ga", "kan", "roo"]

class DirNotList(object):
    def __dir__(self):
        return 7

x = DirNotList()
try:
    dir(x)
except TypeError:
    pass
else:
    raise AssertionError

class DirNotCallable(object):
    __dir__ = 7

x = DirNotCallable()
try:
    dir(x)
except TypeError:
    pass
else:
    raise AssertionError


################################################################################
# example run
################################################################################
#
# Python 2.6a0 (trunk:52633M, Nov  7 2006, 17:28:32) [MSC v.1310 32 bit (Intel)] o
# n win32
# Type "help", "copyright", "credits" or "license" for more information.
# >>> assert dir() == ["__builtins__", "__doc__", "__name__"]
# [26878 refs]
# >>>
# [26878 refs]
# >>> import os
# [26880 refs]
# >>> assert "write" in dir(os)
# [26880 refs]
# >>>
# [26880 refs]
# >>> assert "__add__" in dir(int)
# [26978 refs]
# >>> assert "mro" not in dir(int)
# [26978 refs]
# >>>
# [26978 refs]
# >>> class Foo(object):
# ...     def __init__(self):
# ...         self.x = 17
# ...         self.y = "blah"
# ...         self.z = 8.2
# ...
# [27029 refs]
# >>> x = Foo()
# [27039 refs]
# >>> assert "x" in dir(x)           # instance
# [27039 refs]
# >>> assert "y" in dir(x)           # instance
# [27039 refs]
# >>> assert "z" in dir(x)           # instance
# [27039 refs]
# >>> assert "__init__" in dir(x)    # class
# [27039 refs]
# >>> assert "__getitem__" in dir(x) # bases
# Traceback (most recent call last):
#   File "<stdin>", line 1, in <module>
# AssertionError
# [27072 refs]
# >>>
# [27072 refs]
# >>> class CustomDir(object):
# ...     def __dir__(self):
# ...         return ["kan", "ga", "roo"]
# ...
# [27124 refs]
# >>> x = CustomDir()
# [27117 refs]
# >>> assert dir(x) == ["ga", "kan", "roo"]
# [27117 refs]
# >>>
# [27117 refs]
# >>> class DirNotList(object):
# ...     def __dir__(self):
# ...         return 7
# ...
# [27161 refs]
# >>> x = DirNotList()
# [27161 refs]
# >>> try:
# ...     dir(x)
# ... except TypeError:
# ...     pass
# ... else:
# ...     raise AssertionError
# ...
# [27161 refs]
# >>> class DirNotCallable(object):
# ...     __dir__ = 7
# ...
# [27188 refs]
# >>> x = DirNotCallable()
# [27188 refs]
# >>> try:
# ...     dir(x)
# ... except TypeError:
# ...     pass
# ... else:
# ...     raise AssertionError
# ...
# [27188 refs]
# >>>
################################################################################