Lib/test/test_array.py

#! /usr/bin/env python
"""Test the arraymodule.
   Roger E. Masse
"""

import unittest
from test import test_support
import array, cStringIO, math

tests = [] # list to accumulate all tests
typecodes = "cubBhHiIlLfd"

class BadConstructorTest(unittest.TestCase):

    def test_constructor(self):
        self.assertRaises(TypeError, array.array)
        self.assertRaises(TypeError, array.array, spam=42)
        self.assertRaises(TypeError, array.array, 'xx')
        self.assertRaises(ValueError, array.array, 'x')

tests.append(BadConstructorTest)

class BaseTest(unittest.TestCase):
    # Required class attributes (provided by subclasses
    # typecode: the typecode to test
    # example: an initializer usable in the constructor for this type
    # smallerexample: the same length as example, but smaller
    # biggerexample: the same length as example, but bigger
    # outside: An entry that is not in example
    # minitemsize: the minimum guaranteed itemsize

    def assertEntryEqual(self, entry1, entry2):
        self.assertEqual(entry1, entry2)

    def badtypecode(self):
        # Return a typecode that is different from our own
        return typecodes[(typecodes.index(self.typecode)+1) % len(typecodes)]

    def test_constructor(self):
        a = array.array(self.typecode)
        self.assertEqual(a.typecode, self.typecode)
        self.assert_(a.itemsize>=self.minitemsize)
        self.assertRaises(TypeError, array.array, self.typecode, None)

    def test_len(self):
        a = array.array(self.typecode)
        a.append(self.example[0])
        self.assertEqual(len(a), 1)

        a = array.array(self.typecode, self.example)
        self.assertEqual(len(a), len(self.example))

    def test_buffer_info(self):
        a = array.array(self.typecode, self.example)
        self.assertRaises(TypeError, a.buffer_info, 42)
        bi = a.buffer_info()
        self.assert_(isinstance(bi, tuple))
        self.assertEqual(len(bi), 2)
        self.assert_(isinstance(bi[0], int))
        self.assert_(isinstance(bi[1], int))
        self.assertEqual(bi[1], len(a))

    def test_byteswap(self):
        a = array.array(self.typecode, self.example)
        self.assertRaises(TypeError, a.byteswap, 42)
        if a.itemsize in (1, 2, 4, 8):
            b = array.array(self.typecode, self.example)
            b.byteswap()
            if a.itemsize==1:
                self.assertEqual(a, b)
            else:
                self.assertNotEqual(a, b)
            b.byteswap()
            self.assertEqual(a, b)

    def test_copy(self):
        import copy
        a = array.array(self.typecode, self.example)
        b = copy.copy(a)
        self.assertNotEqual(id(a), id(b))
        self.assertEqual(a, b)

    def test_insert(self):
        a = array.array(self.typecode, self.example)
        a.insert(0, self.example[0])
        self.assertEqual(len(a), 1+len(self.example))
        self.assertEqual(a[0], a[1])
        self.assertRaises(TypeError, a.insert)
        self.assertRaises(TypeError, a.insert, None)
        self.assertRaises(TypeError, a.insert, 0, None)

        a = array.array(self.typecode, self.example)
        a.insert(-1, self.example[0])
        self.assertEqual(
            a,
            array.array(
                self.typecode,
                self.example[:-1] + self.example[:1] + self.example[-1:]
            )
        )

        a = array.array(self.typecode, self.example)
        a.insert(-1000, self.example[0])
        self.assertEqual(
            a,
            array.array(self.typecode, self.example[:1] + self.example)
        )

        a = array.array(self.typecode, self.example)
        a.insert(1000, self.example[0])
        self.assertEqual(
            a,
            array.array(self.typecode, self.example + self.example[:1])
        )

    def test_tofromfile(self):
        a = array.array(self.typecode, 2*self.example)
        self.assertRaises(TypeError, a.tofile)
        self.assertRaises(TypeError, a.tofile, cStringIO.StringIO())
        f = open(test_support.TESTFN, 'wb')
        try:
            a.tofile(f)
            f.close()
            b = array.array(self.typecode)
            f = open(test_support.TESTFN, 'rb')
            self.assertRaises(TypeError, b.fromfile)
            self.assertRaises(
                TypeError,
                b.fromfile,
                cStringIO.StringIO(), len(self.example)
            )
            b.fromfile(f, len(self.example))
            self.assertEqual(b, array.array(self.typecode, self.example))
            self.assertNotEqual(a, b)
            b.fromfile(f, len(self.example))
            self.assertEqual(a, b)
            self.assertRaises(EOFError, b.fromfile, f, 1)
            f.close()
        finally:
            if not f.closed:
                f.close()
            test_support.unlink(test_support.TESTFN)

    def test_tofromlist(self):
        a = array.array(self.typecode, 2*self.example)
        b = array.array(self.typecode)
        self.assertRaises(TypeError, a.tolist, 42)
        self.assertRaises(TypeError, b.fromlist)
        self.assertRaises(TypeError, b.fromlist, 42)
        self.assertRaises(TypeError, b.fromlist, [None])
        b.fromlist(a.tolist())
        self.assertEqual(a, b)

    def test_tofromstring(self):
        a = array.array(self.typecode, 2*self.example)
        b = array.array(self.typecode)
        self.assertRaises(TypeError, a.tostring, 42)
        self.assertRaises(TypeError, b.fromstring)
        self.assertRaises(TypeError, b.fromstring, 42)
        b.fromstring(a.tostring())
        self.assertEqual(a, b)
        if a.itemsize>1:
            self.assertRaises(ValueError, b.fromstring, "x")

    def test_repr(self):
        a = array.array(self.typecode, 2*self.example)
        self.assertEqual(a, eval(repr(a), {"array": array.array}))

        a = array.array(self.typecode)
        self.assertEqual(repr(a), "array('%s')" % self.typecode)

    def test_str(self):
        a = array.array(self.typecode, 2*self.example)
        str(a)

    def test_cmp(self):
        a = array.array(self.typecode, self.example)
        self.assert_((a == 42) is False)
        self.assert_((a != 42) is True)

        self.assert_((a == a) is True)
        self.assert_((a != a) is False)
        self.assert_((a < a) is False)
        self.assert_((a <= a) is True)
        self.assert_((a > a) is False)
        self.assert_((a >= a) is True)

        as = array.array(self.typecode, self.smallerexample)
        ab = array.array(self.typecode, self.biggerexample)

        self.assert_((a == 2*a) is False)
        self.assert_((a != 2*a) is True)
        self.assert_((a < 2*a) is True)
        self.assert_((a <= 2*a) is True)
        self.assert_((a > 2*a) is False)
        self.assert_((a >= 2*a) is False)

        self.assert_((a == as) is False)
        self.assert_((a != as) is True)
        self.assert_((a < as) is False)
        self.assert_((a <= as) is False)
        self.assert_((a > as) is True)
        self.assert_((a >= as) is True)

        self.assert_((a == ab) is False)
        self.assert_((a != ab) is True)
        self.assert_((a < ab) is True)
        self.assert_((a <= ab) is True)
        self.assert_((a > ab) is False)
        self.assert_((a >= ab) is False)

    def test_add(self):
        a = array.array(self.typecode, self.example) \
            + array.array(self.typecode, self.example[::-1])
        self.assertEqual(
            a,
            array.array(self.typecode, self.example + self.example[::-1])
        )

        b = array.array(self.badtypecode())
        self.assertRaises(TypeError, a.__add__, b)

        self.assertRaises(TypeError, a.__add__, "bad")

    def test_iadd(self):
        a = array.array(self.typecode, self.example[::-1])
        b = a
        a += array.array(self.typecode, 2*self.example)
        self.assert_(a is b)
        self.assertEqual(
            a,
            array.array(self.typecode, self.example[::-1]+2*self.example)
        )

        b = array.array(self.badtypecode())
        self.assertRaises(TypeError, a.__add__, b)

        self.assertRaises(TypeError, a.__iadd__, "bad")

    def test_mul(self):
        a = 5*array.array(self.typecode, self.example)
        self.assertEqual(
            a,
            array.array(self.typecode, 5*self.example)
        )

        a = array.array(self.typecode, self.example)*5
        self.assertEqual(
            a,
            array.array(self.typecode, self.example*5)
        )

        a = 0*array.array(self.typecode, self.example)
        self.assertEqual(
            a,
            array.array(self.typecode)
        )

        a = (-1)*array.array(self.typecode, self.example)
        self.assertEqual(
            a,
            array.array(self.typecode)
        )

        self.assertRaises(TypeError, a.__mul__, "bad")

    def test_imul(self):
        a = array.array(self.typecode, self.example)
        b = a

        a *= 5
        self.assert_(a is b)
        self.assertEqual(
            a,
            array.array(self.typecode, 5*self.example)
        )

        a *= 0
        self.assert_(a is b)
        self.assertEqual(a, array.array(self.typecode))

        a *= 1000
        self.assert_(a is b)
        self.assertEqual(a, array.array(self.typecode))

        a *= -1
        self.assert_(a is b)
        self.assertEqual(a, array.array(self.typecode))

        a = array.array(self.typecode, self.example)
        a *= -1
        self.assertEqual(a, array.array(self.typecode))

        self.assertRaises(TypeError, a.__imul__, "bad")

    def test_getitem(self):
        a = array.array(self.typecode, self.example)
        self.assertEntryEqual(a[0], self.example[0])
        self.assertEntryEqual(a[0L], self.example[0])
        self.assertEntryEqual(a[-1], self.example[-1])
        self.assertEntryEqual(a[-1L], self.example[-1])
        self.assertEntryEqual(a[len(self.example)-1], self.example[-1])
        self.assertEntryEqual(a[-len(self.example)], self.example[0])
        self.assertRaises(TypeError, a.__getitem__)
        self.assertRaises(IndexError, a.__getitem__, len(self.example))
        self.assertRaises(IndexError, a.__getitem__, -len(self.example)-1)

    def test_setitem(self):
        a = array.array(self.typecode, self.example)
        a[0] = a[-1]
        self.assertEntryEqual(a[0], a[-1])

        a = array.array(self.typecode, self.example)
        a[0L] = a[-1]
        self.assertEntryEqual(a[0], a[-1])

        a = array.array(self.typecode, self.example)
        a[-1] = a[0]
        self.assertEntryEqual(a[0], a[-1])

        a = array.array(self.typecode, self.example)
        a[-1L] = a[0]
        self.assertEntryEqual(a[0], a[-1])

        a = array.array(self.typecode, self.example)
        a[len(self.example)-1] = a[0]
        self.assertEntryEqual(a[0], a[-1])

        a = array.array(self.typecode, self.example)
        a[-len(self.example)] = a[-1]
        self.assertEntryEqual(a[0], a[-1])

        self.assertRaises(TypeError, a.__setitem__)
        self.assertRaises(TypeError, a.__setitem__, None)
        self.assertRaises(TypeError, a.__setitem__, 0, None)
        self.assertRaises(
            IndexError,
            a.__setitem__,
            len(self.example), self.example[0]
        )
        self.assertRaises(
            IndexError,
            a.__setitem__,
            -len(self.example)-1, self.example[0]
        )

    def test_delitem(self):
        a = array.array(self.typecode, self.example)
        del a[0]
        self.assertEqual(
            a,
            array.array(self.typecode, self.example[1:])
        )

        a = array.array(self.typecode, self.example)
        del a[-1]
        self.assertEqual(
            a,
            array.array(self.typecode, self.example[:-1])
        )

        a = array.array(self.typecode, self.example)
        del a[len(self.example)-1]
        self.assertEqual(
            a,
            array.array(self.typecode, self.example[:-1])
        )

        a = array.array(self.typecode, self.example)
        del a[-len(self.example)]
        self.assertEqual(
            a,
            array.array(self.typecode, self.example[1:])
        )

        self.assertRaises(TypeError, a.__delitem__)
        self.assertRaises(TypeError, a.__delitem__, None)
        self.assertRaises(IndexError, a.__delitem__, len(self.example))
        self.assertRaises(IndexError, a.__delitem__, -len(self.example)-1)

    def test_getslice(self):
        a = array.array(self.typecode, self.example)
        self.assertEqual(a[:], a)

        self.assertEqual(
            a[1:],
            array.array(self.typecode, self.example[1:])
        )

        self.assertEqual(
            a[:1],
            array.array(self.typecode, self.example[:1])
        )

        self.assertEqual(
            a[:-1],
            array.array(self.typecode, self.example[:-1])
        )

        self.assertEqual(
            a[-1:],
            array.array(self.typecode, self.example[-1:])
        )

        self.assertEqual(
            a[-1:-1],
            array.array(self.typecode)
        )

        self.assertEqual(
            a[1000:],
            array.array(self.typecode)
        )
        self.assertEqual(a[-1000:], a)
        self.assertEqual(a[:1000], a)
        self.assertEqual(
            a[:-1000],
            array.array(self.typecode)
        )
        self.assertEqual(a[-1000:1000], a)
        self.assertEqual(
            a[2000:1000],
            array.array(self.typecode)
        )

    def test_setslice(self):
        a = array.array(self.typecode, self.example)
        a[:1] = a
        self.assertEqual(
            a,
            array.array(self.typecode, self.example + self.example[1:])
        )

        a = array.array(self.typecode, self.example)
        a[:-1] = a
        self.assertEqual(
            a,
            array.array(self.typecode, self.example + self.example[-1:])
        )

        a = array.array(self.typecode, self.example)
        a[-1:] = a
        self.assertEqual(
            a,
            array.array(self.typecode, self.example[:-1] + self.example)
        )

        a = array.array(self.typecode, self.example)
        a[1:] = a
        self.assertEqual(
            a,
            array.array(self.typecode, self.example[:1] + self.example)
        )

        a = array.array(self.typecode, self.example)
        a[1:-1] = a
        self.assertEqual(
            a,
            array.array(
                self.typecode,
                self.example[:1] + self.example + self.example[-1:]
            )
        )

        a = array.array(self.typecode, self.example)
        a[1000:] = a
        self.assertEqual(
            a,
            array.array(self.typecode, 2*self.example)
        )

        a = array.array(self.typecode, self.example)
        a[-1000:] = a
        self.assertEqual(
            a,
            array.array(self.typecode, self.example)
        )

        a = array.array(self.typecode, self.example)
        a[:1000] = a
        self.assertEqual(
            a,
            array.array(self.typecode, self.example)
        )

        a = array.array(self.typecode, self.example)
        a[:-1000] = a
        self.assertEqual(
            a,
            array.array(self.typecode, 2*self.example)
        )

        a = array.array(self.typecode, self.example)
        a[1:0] = a
        self.assertEqual(
            a,
            array.array(self.typecode, self.example[:1] + self.example + self.example[1:])
        )

        a = array.array(self.typecode, self.example)
        a[2000:1000] = a
        self.assertEqual(
            a,
            array.array(self.typecode, 2*self.example)
        )

        a = array.array(self.typecode, self.example)
        self.assertRaises(TypeError, a.__setslice__, 0, 0, None)
        self.assertRaises(TypeError, a.__setitem__, slice(0, 1), None)

        b = array.array(self.badtypecode())
        self.assertRaises(TypeError, a.__setslice__, 0, 0, b)
        self.assertRaises(TypeError, a.__setitem__, slice(0, 1), b)

    def test_index(self):
        example = 2*self.example
        a = array.array(self.typecode, example)
        self.assertRaises(TypeError, a.index)
        for x in example:
            self.assertEqual(a.index(x), example.index(x))
        self.assertRaises(ValueError, a.index, None)
        self.assertRaises(ValueError, a.index, self.outside)

    def test_count(self):
        example = 2*self.example
        a = array.array(self.typecode, example)
        self.assertRaises(TypeError, a.count)
        for x in example:
            self.assertEqual(a.count(x), example.count(x))
        self.assertEqual(a.count(self.outside), 0)
        self.assertEqual(a.count(None), 0)

    def test_remove(self):
        for x in self.example:
            example = 2*self.example
            a = array.array(self.typecode, example)
            pos = example.index(x)
            example2 = example[:pos] + example[pos+1:]
            a.remove(x)
            self.assertEqual(a, array.array(self.typecode, example2))

        a = array.array(self.typecode, self.example)
        self.assertRaises(ValueError, a.remove, self.outside)

        self.assertRaises(ValueError, a.remove, None)

    def test_pop(self):
        a = array.array(self.typecode)
        self.assertRaises(IndexError, a.pop)

        a = array.array(self.typecode, 2*self.example)
        self.assertRaises(TypeError, a.pop, 42, 42)
        self.assertRaises(TypeError, a.pop, None)
        self.assertRaises(IndexError, a.pop, len(a))
        self.assertRaises(IndexError, a.pop, -len(a)-1)

        self.assertEntryEqual(a.pop(0), self.example[0])
        self.assertEqual(
            a,
            array.array(self.typecode, self.example[1:]+self.example)
        )
        self.assertEntryEqual(a.pop(1), self.example[2])
        self.assertEqual(
            a,
            array.array(self.typecode, self.example[1:2]+self.example[3:]+self.example)
        )
        self.assertEntryEqual(a.pop(0), self.example[1])
        self.assertEntryEqual(a.pop(), self.example[-1])
        self.assertEqual(
            a,
            array.array(self.typecode, self.example[3:]+self.example[:-1])
        )

    def test_reverse(self):
        a = array.array(self.typecode, self.example)
        self.assertRaises(TypeError, a.reverse, 42)
        a.reverse()
        self.assertEqual(
            a,
            array.array(self.typecode, self.example[::-1])
        )

    def test_extend(self):
        a = array.array(self.typecode, self.example)
        self.assertRaises(TypeError, a.extend)
        a.extend(array.array(self.typecode, self.example[::-1]))
        self.assertEqual(
            a,
            array.array(self.typecode, self.example+self.example[::-1])
        )

        b = array.array(self.badtypecode())
        self.assertRaises(TypeError, a.extend, b)

    def test_coveritertraverse(self):
        try:
            import gc
        except ImportError:
            return
        a = array.array(self.typecode)
        l = [iter(a)]
        l.append(l)
        gc.collect()

    def test_buffer(self):
        a = array.array(self.typecode, self.example)
        b = buffer(a)
        self.assertEqual(b[0], a.tostring()[0])

    def test_bug_782369(self):
        import sys
        if hasattr(sys, "getrefcount"):
            for i in range(10):
                b = array.array('B', range(64))
            rc = sys.getrefcount(10)
            for i in range(10):
                b = array.array('B', range(64))
            self.assertEqual(rc, sys.getrefcount(10))

class StringTest(BaseTest):

    def test_setitem(self):
        super(StringTest, self).test_setitem()
        a = array.array(self.typecode, self.example)
        self.assertRaises(TypeError, a.__setitem__, 0, self.example[:2])

class CharacterTest(StringTest):
    typecode = 'c'
    example = '\x01azAZ\x00\xfe'
    smallerexample = '\x01azAY\x00\xfe'
    biggerexample = '\x01azAZ\x00\xff'
    outside = '\x33'
    minitemsize = 1

    def test_subbclassing(self):
        class EditableString(array.array):
            def __new__(cls, s, *args, **kwargs):
                return array.array.__new__(cls, 'c', s)

            def __init__(self, s, color='blue'):
                array.array.__init__(self, 'c', s)
                self.color = color

            def strip(self):
                self[:] = array.array('c', self.tostring().strip())

            def __repr__(self):
                return 'EditableString(%r)' % self.tostring()

        s = EditableString("\ttest\r\n")
        s.strip()
        self.assertEqual(s.tostring(), "test")

        self.assertEqual(s.color, "blue")
        s.color = "red"
        self.assertEqual(s.color, "red")
        self.assertEqual(s.__dict__.keys(), ["color"])

    def test_nounicode(self):
        a = array.array(self.typecode, self.example)
        self.assertRaises(ValueError, a.fromunicode, unicode(''))
        self.assertRaises(ValueError, a.tounicode)

tests.append(CharacterTest)

if test_support.have_unicode:
    class UnicodeTest(StringTest):
        typecode = 'u'
        example = unicode(r'\x01\u263a\x00\ufeff', 'unicode-escape')
        smallerexample = unicode(r'\x01\u263a\x00\ufefe', 'unicode-escape')
        biggerexample = unicode(r'\x01\u263a\x01\ufeff', 'unicode-escape')
        outside = unicode('\x33')
        minitemsize = 2

        def test_unicode(self):
            self.assertRaises(TypeError, array.array, 'b', unicode('foo', 'ascii'))

            a = array.array('u', unicode(r'\xa0\xc2\u1234', 'unicode-escape'))
            a.fromunicode(unicode(' ', 'ascii'))
            a.fromunicode(unicode('', 'ascii'))
            a.fromunicode(unicode('', 'ascii'))
            a.fromunicode(unicode(r'\x11abc\xff\u1234', 'unicode-escape'))
            s = a.tounicode()
            self.assertEqual(
                s,
                unicode(r'\xa0\xc2\u1234 \x11abc\xff\u1234', 'unicode-escape')
            )

            s = unicode(r'\x00="\'a\\b\x80\xff\u0000\u0001\u1234', 'unicode-escape')
            a = array.array('u', s)
            self.assertEqual(
                repr(a),
                r"""array('u', u'\x00="\'a\\b\x80\xff\x00\x01\u1234')"""
            )

            self.assertRaises(TypeError, a.fromunicode)

    tests.append(UnicodeTest)

class NumberTest(BaseTest):

    def test_extslice(self):
        a = array.array(self.typecode, range(5))
        self.assertEqual(a[::], a)
        self.assertEqual(a[::2], array.array(self.typecode, [0,2,4]))
        self.assertEqual(a[1::2], array.array(self.typecode, [1,3]))
        self.assertEqual(a[::-1], array.array(self.typecode, [4,3,2,1,0]))
        self.assertEqual(a[::-2], array.array(self.typecode, [4,2,0]))
        self.assertEqual(a[3::-2], array.array(self.typecode, [3,1]))
        self.assertEqual(a[-100:100:], a)
        self.assertEqual(a[100:-100:-1], a[::-1])
        self.assertEqual(a[-100L:100L:2L], array.array(self.typecode, [0,2,4]))
        self.assertEqual(a[1000:2000:2], array.array(self.typecode, []))
        self.assertEqual(a[-1000:-2000:-2], array.array(self.typecode, []))

    def test_delslice(self):
        a = array.array(self.typecode, range(5))
        del a[::2]
        self.assertEqual(a, array.array(self.typecode, [1,3]))
        a = array.array(self.typecode, range(5))
        del a[1::2]
        self.assertEqual(a, array.array(self.typecode, [0,2,4]))
        a = array.array(self.typecode, range(5))
        del a[1::-2]
        self.assertEqual(a, array.array(self.typecode, [0,2,3,4]))
        a = array.array(self.typecode, range(10))
        del a[::1000]
        self.assertEqual(a, array.array(self.typecode, [1,2,3,4,5,6,7,8,9]))

    def test_assignment(self):
        a = array.array(self.typecode, range(10))
        a[::2] = array.array(self.typecode, [42]*5)
        self.assertEqual(a, array.array(self.typecode, [42, 1, 42, 3, 42, 5, 42, 7, 42, 9]))
        a = array.array(self.typecode, range(10))
        a[::-4] = array.array(self.typecode, [10]*3)
        self.assertEqual(a, array.array(self.typecode, [0, 10, 2, 3, 4, 10, 6, 7, 8 ,10]))
        a = array.array(self.typecode, range(4))
        a[::-1] = a
        self.assertEqual(a, array.array(self.typecode, [3, 2, 1, 0]))
        a = array.array(self.typecode, range(10))
        b = a[:]
        c = a[:]
        ins = array.array(self.typecode, range(2))
        a[2:3] = ins
        b[slice(2,3)] = ins
        c[2:3:] = ins

    def test_iterationcontains(self):
        a = array.array(self.typecode, range(10))
        self.assertEqual(list(a), range(10))
        b = array.array(self.typecode, [20])
        self.assertEqual(a[-1] in a, True)
        self.assertEqual(b[0] not in a, True)

    def check_overflow(self, lower, upper):
        # method to be used by subclasses

        # should not overflow assigning lower limit
        a = array.array(self.typecode, [lower])
        a[0] = lower
        # should overflow assigning less than lower limit
        self.assertRaises(OverflowError, array.array, self.typecode, [lower-1])
        self.assertRaises(OverflowError, a.__setitem__, 0, lower-1)
        # should not overflow assigning upper limit
        a = array.array(self.typecode, [upper])
        a[0] = upper
        # should overflow assigning more than upper limit
        self.assertRaises(OverflowError, array.array, self.typecode, [upper+1])
        self.assertRaises(OverflowError, a.__setitem__, 0, upper+1)

    def test_subclassing(self):
        typecode = self.typecode
        class ExaggeratingArray(array.array):
            __slots__ = ['offset']

            def __new__(cls, typecode, data, offset):
                return array.array.__new__(cls, typecode, data)

            def __init__(self, typecode, data, offset):
                self.offset = offset

            def __getitem__(self, i):
                return array.array.__getitem__(self, i) + self.offset

        a = ExaggeratingArray(self.typecode, [3, 6, 7, 11], 4)
        self.assertEntryEqual(a[0], 7)

        self.assertRaises(AttributeError, setattr, a, "color", "blue")

class SignedNumberTest(NumberTest):
    example = [-1, 0, 1, 42, 0x7f]
    smallerexample = [-1, 0, 1, 42, 0x7e]
    biggerexample = [-1, 0, 1, 43, 0x7f]
    outside = 23

    def test_overflow(self):
        a = array.array(self.typecode)
        lower = -1 * long(pow(2, a.itemsize * 8 - 1))
        upper = long(pow(2, a.itemsize * 8 - 1)) - 1L
        self.check_overflow(lower, upper)

class UnsignedNumberTest(NumberTest):
    example = [0, 1, 17, 23, 42, 0xff]
    smallerexample = [0, 1, 17, 23, 42, 0xfe]
    biggerexample = [0, 1, 17, 23, 43, 0xff]
    outside = 0xaa

    def test_overflow(self):
        a = array.array(self.typecode)
        lower = 0
        upper = long(pow(2, a.itemsize * 8)) - 1L
        self.check_overflow(lower, upper)


class ByteTest(SignedNumberTest):
    typecode = 'b'
    minitemsize = 1
tests.append(ByteTest)

class UnsignedByteTest(UnsignedNumberTest):
    typecode = 'B'
    minitemsize = 1
tests.append(UnsignedByteTest)

class ShortTest(SignedNumberTest):
    typecode = 'h'
    minitemsize = 2
tests.append(ShortTest)

class UnsignedShortTest(UnsignedNumberTest):
    typecode = 'H'
    minitemsize = 2
tests.append(UnsignedShortTest)

class IntTest(SignedNumberTest):
    typecode = 'i'
    minitemsize = 2
tests.append(IntTest)

class UnsignedIntTest(UnsignedNumberTest):
    typecode = 'I'
    minitemsize = 2
tests.append(UnsignedIntTest)

class LongTest(SignedNumberTest):
    typecode = 'l'
    minitemsize = 4
tests.append(LongTest)

class UnsignedLongTest(UnsignedNumberTest):
    typecode = 'L'
    minitemsize = 4
tests.append(UnsignedLongTest)

class FPTest(NumberTest):
    example = [-42.0, 0, 42, 1e5, -1e10]
    smallerexample = [-42.0, 0, 42, 1e5, -2e10]
    biggerexample = [-42.0, 0, 42, 1e5, 1e10]
    outside = 23

    def assertEntryEqual(self, entry1, entry2):
        self.assertAlmostEqual(entry1, entry2)

    def test_byteswap(self):
        a = array.array(self.typecode, self.example)
        self.assertRaises(TypeError, a.byteswap, 42)
        if a.itemsize in (1, 2, 4, 8):
            b = array.array(self.typecode, self.example)
            b.byteswap()
            if a.itemsize==1:
                self.assertEqual(a, b)
            else:
                # On alphas treating the byte swapped bit patters as
                # floats/doubles results in floating point exceptions
                # => compare the 8bit string values instead
                self.assertNotEqual(a.tostring(), b.tostring())
            b.byteswap()
            self.assertEqual(a, b)

class FloatTest(FPTest):
    typecode = 'f'
    minitemsize = 4
tests.append(FloatTest)

class DoubleTest(FPTest):
    typecode = 'd'
    minitemsize = 8
tests.append(DoubleTest)

def test_main():
    test_support.run_unittest(*tests)

if __name__=="__main__":
    test_main()