241 lines
10 KiB
Python
241 lines
10 KiB
Python
import unittest
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from forth import (
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evaluate,
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StackUnderflowError,
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)
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# Tests adapted from `problem-specifications//canonical-data.json`
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class ForthTest(unittest.TestCase):
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def test_parsing_and_numbers_numbers_just_get_pushed_onto_the_stack(self):
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self.assertEqual(evaluate(["1 2 3 4 5"]), [1, 2, 3, 4, 5])
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def test_addition_can_add_two_numbers(self):
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self.assertEqual(evaluate(["1 2 +"]), [3])
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def test_addition_errors_if_there_is_nothing_on_the_stack(self):
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with self.assertRaises(StackUnderflowError) as err:
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evaluate(["+"])
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self.assertEqual(type(err.exception), StackUnderflowError)
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self.assertEqual(
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str(err.exception.args[0]), "Insufficient number of items in stack"
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)
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def test_addition_errors_if_there_is_only_one_value_on_the_stack(self):
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with self.assertRaises(StackUnderflowError) as err:
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evaluate(["1 +"])
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self.assertEqual(type(err.exception), StackUnderflowError)
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self.assertEqual(
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str(err.exception.args[0]), "Insufficient number of items in stack"
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)
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def test_subtraction_can_subtract_two_numbers(self):
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self.assertEqual(evaluate(["3 4 -"]), [-1])
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def test_subtraction_errors_if_there_is_nothing_on_the_stack(self):
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with self.assertRaises(StackUnderflowError) as err:
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evaluate(["-"])
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self.assertEqual(type(err.exception), StackUnderflowError)
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self.assertEqual(
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str(err.exception.args[0]), "Insufficient number of items in stack"
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)
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def test_subtraction_errors_if_there_is_only_one_value_on_the_stack(self):
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with self.assertRaises(StackUnderflowError) as err:
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evaluate(["1 -"])
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self.assertEqual(type(err.exception), StackUnderflowError)
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self.assertEqual(
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str(err.exception.args[0]), "Insufficient number of items in stack"
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)
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def test_multiplication_can_multiply_two_numbers(self):
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self.assertEqual(evaluate(["2 4 *"]), [8])
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def test_multiplication_errors_if_there_is_nothing_on_the_stack(self):
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with self.assertRaises(StackUnderflowError) as err:
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evaluate(["*"])
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self.assertEqual(type(err.exception), StackUnderflowError)
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self.assertEqual(
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str(err.exception.args[0]), "Insufficient number of items in stack"
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)
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def test_multiplication_errors_if_there_is_only_one_value_on_the_stack(self):
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with self.assertRaises(StackUnderflowError) as err:
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evaluate(["1 *"])
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self.assertEqual(type(err.exception), StackUnderflowError)
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self.assertEqual(
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str(err.exception.args[0]), "Insufficient number of items in stack"
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)
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def test_division_can_divide_two_numbers(self):
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self.assertEqual(evaluate(["12 3 /"]), [4])
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def test_division_performs_integer_division(self):
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self.assertEqual(evaluate(["8 3 /"]), [2])
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def test_division_errors_if_dividing_by_zero(self):
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# divide by zero
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with self.assertRaises(ZeroDivisionError) as err:
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evaluate(["4 0 /"])
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self.assertEqual(type(err.exception), ZeroDivisionError)
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self.assertEqual(str(err.exception.args[0]), "divide by zero")
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def test_division_errors_if_there_is_nothing_on_the_stack(self):
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with self.assertRaises(StackUnderflowError) as err:
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evaluate(["/"])
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self.assertEqual(type(err.exception), StackUnderflowError)
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self.assertEqual(
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str(err.exception.args[0]), "Insufficient number of items in stack"
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)
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def test_division_errors_if_there_is_only_one_value_on_the_stack(self):
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with self.assertRaises(StackUnderflowError) as err:
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evaluate(["1 /"])
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self.assertEqual(type(err.exception), StackUnderflowError)
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self.assertEqual(
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str(err.exception.args[0]), "Insufficient number of items in stack"
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)
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def test_combined_arithmetic_addition_and_subtraction(self):
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self.assertEqual(evaluate(["1 2 + 4 -"]), [-1])
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def test_combined_arithmetic_multiplication_and_division(self):
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self.assertEqual(evaluate(["2 4 * 3 /"]), [2])
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def test_dup_copies_a_value_on_the_stack(self):
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self.assertEqual(evaluate(["1 dup"]), [1, 1])
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def test_dup_copies_the_top_value_on_the_stack(self):
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self.assertEqual(evaluate(["1 2 dup"]), [1, 2, 2])
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def test_dup_errors_if_there_is_nothing_on_the_stack(self):
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with self.assertRaises(StackUnderflowError) as err:
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evaluate(["dup"])
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self.assertEqual(type(err.exception), StackUnderflowError)
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self.assertEqual(
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str(err.exception.args[0]), "Insufficient number of items in stack"
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)
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def test_drop_removes_the_top_value_on_the_stack_if_it_is_the_only_one(self):
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self.assertEqual(evaluate(["1 drop"]), [])
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def test_drop_removes_the_top_value_on_the_stack_if_it_is_not_the_only_one(self):
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self.assertEqual(evaluate(["1 2 drop"]), [1])
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def test_drop_errors_if_there_is_nothing_on_the_stack(self):
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with self.assertRaises(StackUnderflowError) as err:
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evaluate(["drop"])
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self.assertEqual(type(err.exception), StackUnderflowError)
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self.assertEqual(
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str(err.exception.args[0]), "Insufficient number of items in stack"
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)
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def test_swap_swaps_the_top_two_values_on_the_stack_if_they_are_the_only_ones(self):
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self.assertEqual(evaluate(["1 2 swap"]), [2, 1])
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def test_swap_swaps_the_top_two_values_on_the_stack_if_they_are_not_the_only_ones(
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self,
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):
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self.assertEqual(evaluate(["1 2 3 swap"]), [1, 3, 2])
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def test_swap_errors_if_there_is_nothing_on_the_stack(self):
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with self.assertRaises(StackUnderflowError) as err:
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evaluate(["swap"])
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self.assertEqual(type(err.exception), StackUnderflowError)
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self.assertEqual(
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str(err.exception.args[0]), "Insufficient number of items in stack"
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)
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def test_swap_errors_if_there_is_only_one_value_on_the_stack(self):
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with self.assertRaises(StackUnderflowError) as err:
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evaluate(["1 swap"])
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self.assertEqual(type(err.exception), StackUnderflowError)
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self.assertEqual(
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str(err.exception.args[0]), "Insufficient number of items in stack"
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)
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def test_over_copies_the_second_element_if_there_are_only_two(self):
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self.assertEqual(evaluate(["1 2 over"]), [1, 2, 1])
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def test_over_copies_the_second_element_if_there_are_more_than_two(self):
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self.assertEqual(evaluate(["1 2 3 over"]), [1, 2, 3, 2])
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def test_over_errors_if_there_is_nothing_on_the_stack(self):
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with self.assertRaises(StackUnderflowError) as err:
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evaluate(["over"])
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self.assertEqual(type(err.exception), StackUnderflowError)
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self.assertEqual(
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str(err.exception.args[0]), "Insufficient number of items in stack"
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)
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def test_over_errors_if_there_is_only_one_value_on_the_stack(self):
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with self.assertRaises(StackUnderflowError) as err:
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evaluate(["1 over"])
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self.assertEqual(type(err.exception), StackUnderflowError)
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self.assertEqual(
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str(err.exception.args[0]), "Insufficient number of items in stack"
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)
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def test_user_defined_words_can_consist_of_built_in_words(self):
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self.assertEqual(evaluate([": dup-twice dup dup ;", "1 dup-twice"]), [1, 1, 1])
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def test_user_defined_words_execute_in_the_right_order(self):
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self.assertEqual(evaluate([": countup 1 2 3 ;", "countup"]), [1, 2, 3])
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def test_user_defined_words_can_override_other_user_defined_words(self):
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self.assertEqual(
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evaluate([": foo dup ;", ": foo dup dup ;", "1 foo"]), [1, 1, 1]
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)
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def test_user_defined_words_can_override_built_in_words(self):
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self.assertEqual(evaluate([": swap dup ;", "1 swap"]), [1, 1])
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def test_user_defined_words_can_override_built_in_operators(self):
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self.assertEqual(evaluate([": + * ;", "3 4 +"]), [12])
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def test_user_defined_words_can_use_different_words_with_the_same_name(self):
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self.assertEqual(
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evaluate([": foo 5 ;", ": bar foo ;", ": foo 6 ;", "bar foo"]), [5, 6]
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)
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def test_user_defined_words_can_define_word_that_uses_word_with_the_same_name(self):
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self.assertEqual(evaluate([": foo 10 ;", ": foo foo 1 + ;", "foo"]), [11])
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def test_user_defined_words_cannot_redefine_non_negative_numbers(self):
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with self.assertRaises(ValueError) as err:
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evaluate([": 1 2 ;"])
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self.assertEqual(type(err.exception), ValueError)
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self.assertEqual(str(err.exception.args[0]), "illegal operation")
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def test_user_defined_words_cannot_redefine_negative_numbers(self):
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with self.assertRaises(ValueError) as err:
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evaluate([": -1 2 ;"])
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self.assertEqual(type(err.exception), ValueError)
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self.assertEqual(str(err.exception.args[0]), "illegal operation")
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def test_user_defined_words_errors_if_executing_a_non_existent_word(self):
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with self.assertRaises(ValueError) as err:
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evaluate(["foo"])
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self.assertEqual(type(err.exception), ValueError)
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self.assertEqual(str(err.exception.args[0]), "undefined operation")
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def test_case_insensitivity_dup_is_case_insensitive(self):
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self.assertEqual(evaluate(["1 DUP Dup dup"]), [1, 1, 1, 1])
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def test_case_insensitivity_drop_is_case_insensitive(self):
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self.assertEqual(evaluate(["1 2 3 4 DROP Drop drop"]), [1])
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def test_case_insensitivity_swap_is_case_insensitive(self):
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self.assertEqual(evaluate(["1 2 SWAP 3 Swap 4 swap"]), [2, 3, 4, 1])
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def test_case_insensitivity_over_is_case_insensitive(self):
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self.assertEqual(evaluate(["1 2 OVER Over over"]), [1, 2, 1, 2, 1])
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def test_case_insensitivity_user_defined_words_are_case_insensitive(self):
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self.assertEqual(evaluate([": foo dup ;", "1 FOO Foo foo"]), [1, 1, 1, 1])
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def test_case_insensitivity_definitions_are_case_insensitive(self):
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self.assertEqual(evaluate([": SWAP DUP Dup dup ;", "1 swap"]), [1, 1, 1, 1])
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