# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

"""
Unit tests for L{twisted.python.constants}.
"""

from __future__ import division, absolute_import

from twisted.trial.unittest import TestCase

from twisted.python.constants import (
NamedConstant, Names, ValueConstant, Values, FlagConstant, Flags)


class NamedConstantTests(TestCase):
"""
Tests for the L{twisted.python.constants.NamedConstant} class which is used
to represent individual values.
"""
def setUp(self):
"""
Create a dummy container into which constants can be placed.
"""
class foo(Names):
pass
self.container = foo


def test_name(self):
"""
The C{name} attribute of a L{NamedConstant} refers to the value passed
for the C{name} parameter to C{_realize}.
"""
name = NamedConstant()
name._realize(self.container, "bar", None)
self.assertEqual("bar", name.name)


def test_representation(self):
"""
The string representation of an instance of L{NamedConstant} includes
the container the instances belongs to as well as the instance's name.
"""
name = NamedConstant()
name._realize(self.container, "bar", None)
self.assertEqual("<foo=bar>", repr(name))


def test_equality(self):
"""
A L{NamedConstant} instance compares equal to itself.
"""
name = NamedConstant()
name._realize(self.container, "bar", None)
self.assertTrue(name == name)
self.assertFalse(name != name)


def test_nonequality(self):
"""
Two different L{NamedConstant} instances do not compare equal to each
other.
"""
first = NamedConstant()
first._realize(self.container, "bar", None)
second = NamedConstant()
second._realize(self.container, "bar", None)
self.assertFalse(first == second)
self.assertTrue(first != second)


def test_hash(self):
"""
Because two different L{NamedConstant} instances do not compare as equal
to each other, they also have different hashes to avoid collisions when
added to a C{dict} or C{set}.
"""
first = NamedConstant()
first._realize(self.container, "bar", None)
second = NamedConstant()
second._realize(self.container, "bar", None)
self.assertNotEqual(hash(first), hash(second))



class _ConstantsTestsMixin(object):
"""
Mixin defining test helpers common to multiple types of constants
collections.
"""
def _notInstantiableTest(self, name, cls):
"""
Assert that an attempt to instantiate the constants class raises
C{TypeError}.

@param name: A C{str} giving the name of the constants collection.
@param cls: The constants class to test.
"""
exc = self.assertRaises(TypeError, cls)
self.assertEqual(name + " may not be instantiated.", str(exc))


def _initializedOnceTest(self, container, constantName):
"""
Assert that C{container._enumerants} does not change as a side-effect of
one of its attributes being accessed.

@param container: A L{_ConstantsContainer} subclass which will be
tested.
@param constantName: The name of one of the constants which is an an
attribute of C{container}.
"""
first = container._enumerants

# Accessing an attribute of the container should not have any observable
# side-effect on the _enumerants attribute.
getattr(container, constantName)

second = container._enumerants
self.assertIdentical(first, second)



class NamesTests(TestCase, _ConstantsTestsMixin):
"""
Tests for L{twisted.python.constants.Names}, a base class for containers of
related constaints.
"""
def setUp(self):
"""
Create a fresh new L{Names} subclass for each unit test to use. Since
L{Names} is stateful, re-using the same subclass across test methods
makes exercising all of the implementation code paths difficult.
"""
class METHOD(Names):
"""
A container for some named constants to use in unit tests for
L{Names}.
"""
GET = NamedConstant()
PUT = NamedConstant()
POST = NamedConstant()
DELETE = NamedConstant()

extra = object()

self.METHOD = METHOD


def test_notInstantiable(self):
"""
A subclass of L{Names} raises C{TypeError} if an attempt is made to
instantiate it.
"""
self._notInstantiableTest("METHOD", self.METHOD)


def test_symbolicAttributes(self):
"""
Each name associated with a L{NamedConstant} instance in the definition
of a L{Names} subclass is available as an attribute on the resulting
class.
"""
self.assertTrue(hasattr(self.METHOD, "GET"))
self.assertTrue(hasattr(self.METHOD, "PUT"))
self.assertTrue(hasattr(self.METHOD, "POST"))
self.assertTrue(hasattr(self.METHOD, "DELETE"))


def test_withoutOtherAttributes(self):
"""
As usual, names not defined in the class scope of a L{Names}
subclass are not available as attributes on the resulting class.
"""
self.assertFalse(hasattr(self.METHOD, "foo"))


def test_representation(self):
"""
The string representation of a constant on a L{Names} subclass includes
the name of the L{Names} subclass and the name of the constant itself.
"""
self.assertEqual("<METHOD=GET>", repr(self.METHOD.GET))


def test_lookupByName(self):
"""
Constants can be looked up by name using L{Names.lookupByName}.
"""
method = self.METHOD.lookupByName("GET")
self.assertIdentical(self.METHOD.GET, method)


def test_notLookupMissingByName(self):
"""
Names not defined with a L{NamedConstant} instance cannot be looked up
using L{Names.lookupByName}.
"""
self.assertRaises(ValueError, self.METHOD.lookupByName, "lookupByName")
self.assertRaises(ValueError, self.METHOD.lookupByName, "__init__")
self.assertRaises(ValueError, self.METHOD.lookupByName, "foo")
self.assertRaises(ValueError, self.METHOD.lookupByName, "extra")


def test_name(self):
"""
The C{name} attribute of one of the named constants gives that
constant's name.
"""
self.assertEqual("GET", self.METHOD.GET.name)


def test_attributeIdentity(self):
"""
Repeated access of an attribute associated with a L{NamedConstant} value
in a L{Names} subclass results in the same object.
"""
self.assertIdentical(self.METHOD.GET, self.METHOD.GET)


def test_iterconstants(self):
"""
L{Names.iterconstants} returns an iterator over all of the constants
defined in the class, in the order they were defined.
"""
constants = list(self.METHOD.iterconstants())
self.assertEqual(
[self.METHOD.GET, self.METHOD.PUT,
self.METHOD.POST, self.METHOD.DELETE],
constants)


def test_attributeIterconstantsIdentity(self):
"""
The constants returned from L{Names.iterconstants} are identical to the
constants accessible using attributes.
"""
constants = list(self.METHOD.iterconstants())
self.assertIdentical(self.METHOD.GET, constants[0])
self.assertIdentical(self.METHOD.PUT, constants[1])
self.assertIdentical(self.METHOD.POST, constants[2])
self.assertIdentical(self.METHOD.DELETE, constants[3])


def test_iterconstantsIdentity(self):
"""
The constants returned from L{Names.iterconstants} are identical on each
call to that method.
"""
constants = list(self.METHOD.iterconstants())
again = list(self.METHOD.iterconstants())
self.assertIdentical(again[0], constants[0])
self.assertIdentical(again[1], constants[1])
self.assertIdentical(again[2], constants[2])
self.assertIdentical(again[3], constants[3])


def test_initializedOnce(self):
"""
L{Names._enumerants} is initialized once and its value re-used on
subsequent access.
"""
self._initializedOnceTest(self.METHOD, "GET")


def test_asForeignClassAttribute(self):
"""
A constant defined on a L{Names} subclass may be set as an attribute of
another class and then retrieved using that attribute.
"""
class Another(object):
something = self.METHOD.GET

self.assertIdentical(self.METHOD.GET, Another.something)


def test_asForeignClassAttributeViaInstance(self):
"""
A constant defined on a L{Names} subclass may be set as an attribute of
another class and then retrieved from an instance of that class using
that attribute.
"""
class Another(object):
something = self.METHOD.GET

self.assertIdentical(self.METHOD.GET, Another().something)


def test_notAsAlternateContainerAttribute(self):
"""
It is explicitly disallowed (via a L{ValueError}) to use a constant
defined on a L{Names} subclass as the value of an attribute of another
L{Names} subclass.
"""
def defineIt():
class AnotherNames(Names):
something = self.METHOD.GET

exc = self.assertRaises(ValueError, defineIt)
self.assertEqual(
"Cannot use <METHOD=GET> as the value of an attribute on "
"AnotherNames",
str(exc))



class ValuesTests(TestCase, _ConstantsTestsMixin):
"""
Tests for L{twisted.python.constants.Names}, a base class for containers of
related constaints with arbitrary values.
"""
def setUp(self):
"""
Create a fresh new L{Values} subclass for each unit test to use. Since
L{Values} is stateful, re-using the same subclass across test methods
makes exercising all of the implementation code paths difficult.
"""
class STATUS(Values):
OK = ValueConstant("200")
NOT_FOUND = ValueConstant("404")

self.STATUS = STATUS


def test_notInstantiable(self):
"""
A subclass of L{Values} raises C{TypeError} if an attempt is made to
instantiate it.
"""
self._notInstantiableTest("STATUS", self.STATUS)


def test_symbolicAttributes(self):
"""
Each name associated with a L{ValueConstant} instance in the definition
of a L{Values} subclass is available as an attribute on the resulting
class.
"""
self.assertTrue(hasattr(self.STATUS, "OK"))
self.assertTrue(hasattr(self.STATUS, "NOT_FOUND"))


def test_withoutOtherAttributes(self):
"""
As usual, names not defined in the class scope of a L{Values}
subclass are not available as attributes on the resulting class.
"""
self.assertFalse(hasattr(self.STATUS, "foo"))


def test_representation(self):
"""
The string representation of a constant on a L{Values} subclass includes
the name of the L{Values} subclass and the name of the constant itself.
"""
self.assertEqual("<STATUS=OK>", repr(self.STATUS.OK))


def test_lookupByName(self):
"""
Constants can be looked up by name using L{Values.lookupByName}.
"""
method = self.STATUS.lookupByName("OK")
self.assertIdentical(self.STATUS.OK, method)


def test_notLookupMissingByName(self):
"""
Names not defined with a L{ValueConstant} instance cannot be looked up
using L{Values.lookupByName}.
"""
self.assertRaises(ValueError, self.STATUS.lookupByName, "lookupByName")
self.assertRaises(ValueError, self.STATUS.lookupByName, "__init__")
self.assertRaises(ValueError, self.STATUS.lookupByName, "foo")


def test_lookupByValue(self):
"""
Constants can be looked up by their associated value, defined by the
argument passed to L{ValueConstant}, using L{Values.lookupByValue}.
"""
status = self.STATUS.lookupByValue("200")
self.assertIdentical(self.STATUS.OK, status)


def test_lookupDuplicateByValue(self):
"""
If more than one constant is associated with a particular value,
L{Values.lookupByValue} returns whichever of them is defined first.
"""
class TRANSPORT_MESSAGE(Values):
"""
Message types supported by an SSH transport.
"""
KEX_DH_GEX_REQUEST_OLD = ValueConstant(30)
KEXDH_INIT = ValueConstant(30)

self.assertIdentical(
TRANSPORT_MESSAGE.lookupByValue(30),
TRANSPORT_MESSAGE.KEX_DH_GEX_REQUEST_OLD)


def test_notLookupMissingByValue(self):
"""
L{Values.lookupByValue} raises L{ValueError} when called with a value
with which no constant is associated.
"""
self.assertRaises(ValueError, self.STATUS.lookupByValue, "OK")
self.assertRaises(ValueError, self.STATUS.lookupByValue, 200)
self.assertRaises(ValueError, self.STATUS.lookupByValue, "200.1")


def test_name(self):
"""
The C{name} attribute of one of the constants gives that constant's
name.
"""
self.assertEqual("OK", self.STATUS.OK.name)


def test_attributeIdentity(self):
"""
Repeated access of an attribute associated with a L{ValueConstant} value
in a L{Values} subclass results in the same object.
"""
self.assertIdentical(self.STATUS.OK, self.STATUS.OK)


def test_iterconstants(self):
"""
L{Values.iterconstants} returns an iterator over all of the constants
defined in the class, in the order they were defined.
"""
constants = list(self.STATUS.iterconstants())
self.assertEqual(
[self.STATUS.OK, self.STATUS.NOT_FOUND],
constants)


def test_attributeIterconstantsIdentity(self):
"""
The constants returned from L{Values.iterconstants} are identical to the
constants accessible using attributes.
"""
constants = list(self.STATUS.iterconstants())
self.assertIdentical(self.STATUS.OK, constants[0])
self.assertIdentical(self.STATUS.NOT_FOUND, constants[1])


def test_iterconstantsIdentity(self):
"""
The constants returned from L{Values.iterconstants} are identical on
each call to that method.
"""
constants = list(self.STATUS.iterconstants())
again = list(self.STATUS.iterconstants())
self.assertIdentical(again[0], constants[0])
self.assertIdentical(again[1], constants[1])


def test_initializedOnce(self):
"""
L{Values._enumerants} is initialized once and its value re-used on
subsequent access.
"""
self._initializedOnceTest(self.STATUS, "OK")



class _FlagsTestsMixin(object):
"""
Mixin defining setup code for any tests for L{Flags} subclasses.

@ivar FXF: A L{Flags} subclass created for each test method.
"""
def setUp(self):
"""
Create a fresh new L{Flags} subclass for each unit test to use. Since
L{Flags} is stateful, re-using the same subclass across test methods
makes exercising all of the implementation code paths difficult.
"""
class FXF(Flags):
# Implicitly assign three flag values based on definition order
READ = FlagConstant()
WRITE = FlagConstant()
APPEND = FlagConstant()

# Explicitly assign one flag value by passing it in
EXCLUSIVE = FlagConstant(0x20)

# Implicitly assign another flag value, following the previously
# specified explicit value.
TEXT = FlagConstant()

self.FXF = FXF



class FlagsTests(_FlagsTestsMixin, TestCase, _ConstantsTestsMixin):
"""
Tests for L{twisted.python.constants.Flags}, a base class for containers of
related, combinable flag or bitvector-like constants.
"""
def test_notInstantiable(self):
"""
A subclass of L{Flags} raises L{TypeError} if an attempt is made to
instantiate it.
"""
self._notInstantiableTest("FXF", self.FXF)


def test_symbolicAttributes(self):
"""
Each name associated with a L{FlagConstant} instance in the definition
of a L{Flags} subclass is available as an attribute on the resulting
class.
"""
self.assertTrue(hasattr(self.FXF, "READ"))
self.assertTrue(hasattr(self.FXF, "WRITE"))
self.assertTrue(hasattr(self.FXF, "APPEND"))
self.assertTrue(hasattr(self.FXF, "EXCLUSIVE"))
self.assertTrue(hasattr(self.FXF, "TEXT"))


def test_withoutOtherAttributes(self):
"""
As usual, names not defined in the class scope of a L{Flags} subclass
are not available as attributes on the resulting class.
"""
self.assertFalse(hasattr(self.FXF, "foo"))


def test_representation(self):
"""
The string representation of a constant on a L{Flags} subclass includes
the name of the L{Flags} subclass and the name of the constant itself.
"""
self.assertEqual("<FXF=READ>", repr(self.FXF.READ))


def test_lookupByName(self):
"""
Constants can be looked up by name using L{Flags.lookupByName}.
"""
flag = self.FXF.lookupByName("READ")
self.assertIdentical(self.FXF.READ, flag)


def test_notLookupMissingByName(self):
"""
Names not defined with a L{FlagConstant} instance cannot be looked up
using L{Flags.lookupByName}.
"""
self.assertRaises(ValueError, self.FXF.lookupByName, "lookupByName")
self.assertRaises(ValueError, self.FXF.lookupByName, "__init__")
self.assertRaises(ValueError, self.FXF.lookupByName, "foo")


def test_lookupByValue(self):
"""
Constants can be looked up by their associated value, defined implicitly
by the position in which the constant appears in the class definition or
explicitly by the argument passed to L{FlagConstant}.
"""
flag = self.FXF.lookupByValue(0x01)
self.assertIdentical(flag, self.FXF.READ)

flag = self.FXF.lookupByValue(0x02)
self.assertIdentical(flag, self.FXF.WRITE)

flag = self.FXF.lookupByValue(0x04)
self.assertIdentical(flag, self.FXF.APPEND)

flag = self.FXF.lookupByValue(0x20)
self.assertIdentical(flag, self.FXF.EXCLUSIVE)

flag = self.FXF.lookupByValue(0x40)
self.assertIdentical(flag, self.FXF.TEXT)


def test_lookupDuplicateByValue(self):
"""
If more than one constant is associated with a particular value,
L{Flags.lookupByValue} returns whichever of them is defined first.
"""
class TIMEX(Flags):
# (timex.mode)
ADJ_OFFSET = FlagConstant(0x0001) # time offset

# xntp 3.4 compatibility names
MOD_OFFSET = FlagConstant(0x0001)

self.assertIdentical(TIMEX.lookupByValue(0x0001), TIMEX.ADJ_OFFSET)


def test_notLookupMissingByValue(self):
"""
L{Flags.lookupByValue} raises L{ValueError} when called with a value
with which no constant is associated.
"""
self.assertRaises(ValueError, self.FXF.lookupByValue, 0x10)


def test_name(self):
"""
The C{name} attribute of one of the constants gives that constant's
name.
"""
self.assertEqual("READ", self.FXF.READ.name)


def test_attributeIdentity(self):
"""
Repeated access of an attribute associated with a L{FlagConstant} value
in a L{Flags} subclass results in the same object.
"""
self.assertIdentical(self.FXF.READ, self.FXF.READ)


def test_iterconstants(self):
"""
L{Flags.iterconstants} returns an iterator over all of the constants
defined in the class, in the order they were defined.
"""
constants = list(self.FXF.iterconstants())
self.assertEqual(
[self.FXF.READ, self.FXF.WRITE, self.FXF.APPEND,
self.FXF.EXCLUSIVE, self.FXF.TEXT],
constants)


def test_attributeIterconstantsIdentity(self):
"""
The constants returned from L{Flags.iterconstants} are identical to the
constants accessible using attributes.
"""
constants = list(self.FXF.iterconstants())
self.assertIdentical(self.FXF.READ, constants[0])
self.assertIdentical(self.FXF.WRITE, constants[1])
self.assertIdentical(self.FXF.APPEND, constants[2])
self.assertIdentical(self.FXF.EXCLUSIVE, constants[3])
self.assertIdentical(self.FXF.TEXT, constants[4])


def test_iterconstantsIdentity(self):
"""
The constants returned from L{Flags.iterconstants} are identical on each
call to that method.
"""
constants = list(self.FXF.iterconstants())
again = list(self.FXF.iterconstants())
self.assertIdentical(again[0], constants[0])
self.assertIdentical(again[1], constants[1])
self.assertIdentical(again[2], constants[2])
self.assertIdentical(again[3], constants[3])
self.assertIdentical(again[4], constants[4])


def test_initializedOnce(self):
"""
L{Flags._enumerants} is initialized once and its value re-used on
subsequent access.
"""
self._initializedOnceTest(self.FXF, "READ")



class FlagConstantSimpleOrTests(_FlagsTestsMixin, TestCase):
"""
Tests for the C{|} operator as defined for L{FlagConstant} instances, used
to create new L{FlagConstant} instances representing both of two existing
L{FlagConstant} instances from the same L{Flags} class.
"""
def test_value(self):
"""
The value of the L{FlagConstant} which results from C{|} has all of the
bits set which were set in either of the values of the two original
constants.
"""
flag = self.FXF.READ | self.FXF.WRITE
self.assertEqual(self.FXF.READ.value | self.FXF.WRITE.value, flag.value)


def test_name(self):
"""
The name of the L{FlagConstant} instance which results from C{|}
includes the names of both of the two original constants.
"""
flag = self.FXF.READ | self.FXF.WRITE
self.assertEqual("{READ,WRITE}", flag.name)


def test_representation(self):
"""
The string representation of a L{FlagConstant} instance which results
from C{|} includes the names of both of the two original constants.
"""
flag = self.FXF.READ | self.FXF.WRITE
self.assertEqual("<FXF={READ,WRITE}>", repr(flag))


def test_iterate(self):
"""
A L{FlagConstant} instance which results from C{|} can be
iterated upon to yield the original constants.
"""
self.assertEqual(
set(self.FXF.WRITE & self.FXF.READ), # No flags
set(()))
self.assertEqual(
set(self.FXF.WRITE),
set((self.FXF.WRITE,)))
self.assertEqual(
set(self.FXF.WRITE | self.FXF.EXCLUSIVE),
set((self.FXF.WRITE, self.FXF.EXCLUSIVE)))


def test_membership(self):
"""
A L{FlagConstant} instance which results from C{|} can be
tested for membership.
"""
flags = self.FXF.WRITE | self.FXF.EXCLUSIVE
self.assertIn(self.FXF.WRITE, flags)
self.assertNotIn(self.FXF.READ, flags)


def test_truthiness(self):
"""
Empty flags is false, non-empty flags is true.
"""
self.assertTrue(self.FXF.WRITE)
self.assertTrue(self.FXF.WRITE | self.FXF.EXCLUSIVE)
self.assertFalse(self.FXF.WRITE & self.FXF.EXCLUSIVE)



class FlagConstantSimpleAndTests(_FlagsTestsMixin, TestCase):
"""
Tests for the C{&} operator as defined for L{FlagConstant} instances, used
to create new L{FlagConstant} instances representing the common parts of two
existing L{FlagConstant} instances from the same L{Flags} class.
"""
def test_value(self):
"""
The value of the L{FlagConstant} which results from C{&} has all of the
bits set which were set in both of the values of the two original
constants.
"""
readWrite = (self.FXF.READ | self.FXF.WRITE)
writeAppend = (self.FXF.WRITE | self.FXF.APPEND)
flag = readWrite & writeAppend
self.assertEqual(self.FXF.WRITE.value, flag.value)


def test_name(self):
"""
The name of the L{FlagConstant} instance which results from C{&}
includes the names of only the flags which were set in both of the two
original constants.
"""
readWrite = (self.FXF.READ | self.FXF.WRITE)
writeAppend = (self.FXF.WRITE | self.FXF.APPEND)
flag = readWrite & writeAppend
self.assertEqual("WRITE", flag.name)


def test_representation(self):
"""
The string representation of a L{FlagConstant} instance which results
from C{&} includes the names of only the flags which were set in both
both of the two original constants.
"""
readWrite = (self.FXF.READ | self.FXF.WRITE)
writeAppend = (self.FXF.WRITE | self.FXF.APPEND)
flag = readWrite & writeAppend
self.assertEqual("<FXF=WRITE>", repr(flag))



class FlagConstantSimpleExclusiveOrTests(_FlagsTestsMixin, TestCase):
"""
Tests for the C{^} operator as defined for L{FlagConstant} instances, used
to create new L{FlagConstant} instances representing the uncommon parts of
two existing L{FlagConstant} instances from the same L{Flags} class.
"""
def test_value(self):
"""
The value of the L{FlagConstant} which results from C{^} has all of the
bits set which were set in exactly one of the values of the two original
constants.
"""
readWrite = (self.FXF.READ | self.FXF.WRITE)
writeAppend = (self.FXF.WRITE | self.FXF.APPEND)
flag = readWrite ^ writeAppend
self.assertEqual(self.FXF.READ.value | self.FXF.APPEND.value, flag.value)


def test_name(self):
"""
The name of the L{FlagConstant} instance which results from C{^}
includes the names of only the flags which were set in exactly one of
the two original constants.
"""
readWrite = (self.FXF.READ | self.FXF.WRITE)
writeAppend = (self.FXF.WRITE | self.FXF.APPEND)
flag = readWrite ^ writeAppend
self.assertEqual("{APPEND,READ}", flag.name)


def test_representation(self):
"""
The string representation of a L{FlagConstant} instance which results
from C{^} includes the names of only the flags which were set in exactly
one of the two original constants.
"""
readWrite = (self.FXF.READ | self.FXF.WRITE)
writeAppend = (self.FXF.WRITE | self.FXF.APPEND)
flag = readWrite ^ writeAppend
self.assertEqual("<FXF={APPEND,READ}>", repr(flag))



class FlagConstantNegationTests(_FlagsTestsMixin, TestCase):
"""
Tests for the C{~} operator as defined for L{FlagConstant} instances, used
to create new L{FlagConstant} instances representing all the flags from a
L{Flags} class not set in a particular L{FlagConstant} instance.
"""
def test_value(self):
"""
The value of the L{FlagConstant} which results from C{~} has all of the
bits set which were not set in the original constant.
"""
flag = ~self.FXF.READ
self.assertEqual(
self.FXF.WRITE.value |
self.FXF.APPEND.value |
self.FXF.EXCLUSIVE.value |
self.FXF.TEXT.value,
flag.value)

flag = ~self.FXF.WRITE
self.assertEqual(
self.FXF.READ.value |
self.FXF.APPEND.value |
self.FXF.EXCLUSIVE.value |
self.FXF.TEXT.value,
flag.value)


def test_name(self):
"""
The name of the L{FlagConstant} instance which results from C{~}
includes the names of all the flags which were not set in the original
constant.
"""
flag = ~self.FXF.WRITE
self.assertEqual("{APPEND,EXCLUSIVE,READ,TEXT}", flag.name)


def test_representation(self):
"""
The string representation of a L{FlagConstant} instance which results
from C{~} includes the names of all the flags which were not set in the
original constant.
"""
flag = ~self.FXF.WRITE
self.assertEqual("<FXF={APPEND,EXCLUSIVE,READ,TEXT}>", repr(flag))