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import unittest

from webkitpy.common.memoized import memoized


class _TestObject(object):

    def __init__(self):
        self.call_count = 0

    @memoized
    def memoized_add_one(self, argument):
        self.call_count += 1
        return argument + 1


class MemoizedTest(unittest.TestCase):

    def test_multiple_identical_calls(self):
        # When a function is called multiple times with identical arguments,
        # the call count doesn't increase past 1.
        test = _TestObject()
        self.assertEqual(test.memoized_add_one(1), 2)
        self.assertEqual(test.memoized_add_one(1), 2)
        self.assertEqual(test.call_count, 1)

    def test_different_calls(self):
        # Validate that call_count is working as expected.
        test = _TestObject()
        self.assertEqual(test.memoized_add_one(1), 2)
        self.assertEqual(test.memoized_add_one(2), 3)
        self.assertEqual(test.call_count, 2)

    def test_reassign_function(self):
        # The function can be assigned to a different variable.
        test = _TestObject()
        add_one = test.memoized_add_one
        self.assertEqual(add_one(4), 5)
        self.assertEqual(test.call_count, 1)

    def test_non_hashable_args(self):
        test = _TestObject()
        try:
            test.memoized_add_one([])
            self.fail('Expected TypeError.')
        except TypeError as error:
            self.assertEqual(
                error.message,
                'Cannot call memoized function memoized_add_one with '
                'unhashable arguments: unhashable type: \'list\'')