test_simpleeval.py

'''
    Unit tests for simpleeval.
    --------------------------

    Most of this stuff is pretty basic.

'''
# pylint: disable=too-many-public-methods, missing-docstring

import unittest, operator, ast
import simpleeval
from simpleeval import SimpleEval, NameNotDefined, InvalidExpression, AttributeDoesNotExist, simple_eval

class DRYTest(unittest.TestCase):
    ''' Stuff we need to do every test, let's do here instead..
        Don't Repeat Yourself. '''

    def setUp(self):
        ''' initialize a SimpleEval '''
        self.s = SimpleEval()

    def t(self, expr, shouldbe): #pylint: disable=invalid-name
        ''' test an evaluation of an expression against an expected answer '''
        return self.assertEqual(self.s.eval(expr), shouldbe)

class TestBasic(DRYTest):
    ''' Simple expressions. '''

    def test_maths_with_ints(self):
        ''' simple maths expressions '''

        self.t("21 + 21", 42)
        self.t("6*7", 42)
        self.t("20 + 1 + (10*2) + 1", 42)
        self.t("100/10", 10)
        self.t("12*12", 144)
        self.t("2 ** 10", 1024)
        self.t("100 % 9", 1)

    def test_bools_and_or(self):
        self.t('True and False', False)
        self.t('True or False', True)
        self.t('1 - 1 or 21', True)
        self.t('1 - 1 and 11', False)
        self.t('110 == 100 + 10 and True', True)

    def test_maths_with_floats(self):
        self.t("11.02 - 9.1", 1.92)
        self.t("29.1+39", 68.1)

    def test_comparisons(self):
        # GT & LT:
        self.t("1 > 0", True)
        self.t("100000 < 28", False)
        self.t("-2 < 11", True)
        self.t("+2 < 5", True)
        self.t("0 == 0", True)

        # GtE, LtE
        self.t("-2 <= -2", True)
        self.t("2 >= 2", True)
        self.t("1 >= 12", False)
        self.t("1.09 <= 1967392", True)

    def test_mixed_comparisons(self):
        self.t("1 > 0.999999", True)
        self.t("1 == True", True)  # Note ==, not 'is'.
        self.t("0 == False", True)  # Note ==, not 'is'.
        self.t("False == False", True)
        self.t("False < True", True)

    def test_if_else(self):
        ''' x if y else z '''

        # and test if/else expressions:
        self.t("'a' if 1 == 1 else 'b'", 'a')
        self.t("'a' if 1 > 2 else 'b'", 'b')

        # and more complex expressions:
        self.t("'a' if 4 < 1 else 'b' if 1 == 2 else 'c'", 'c')

    def test_default_conversions(self):
        ''' conversion between types '''

        self.t('int("20") + int(0.22*100)', 42)
        self.t('float("42")', 42.0)
        self.t('"Test Stuff!" + str(11)', "Test Stuff!11")

    def test_slicing(self):
        self.s.operators[ast.Slice] = operator.getslice if hasattr(operator, "getslice") else operator.getitem
        self.t("'hello'[1]", "e")
        self.t("'hello'[:]", "hello")
        self.t("'hello'[:3]", "hel")
        self.t("'hello'[3:]", "lo")
        self.t("'hello'[::2]", "hlo")
        self.t("'hello'[::-1]", "olleh")
        self.t("'hello'[3::]", "lo")
        self.t("'hello'[:3:]", "hel")
        self.t("'hello'[1:3]", "el")
        self.t("'hello'[1:3:]", "el")
        self.t("'hello'[1::2]", "el")
        self.t("'hello'[:1:2]", "h")
        self.t("'hello'[1:3:1]", "el")
        self.t("'hello'[1:3:2]", "e")

class TestFunctions(DRYTest):
    ''' Functions for expressions to play with '''

    def test_load_file(self):
        ''' add in a function which loads data from an external file. '''

        # write to the file:

        with open("file.txt", 'w') as f:
            f.write("42")

        # define the function we'll send to the eval'er

        def load_file(filename):
            ''' load a file and return its contents '''
            with open(filename) as f:
                return f.read()

        # simple load:

        self.s.functions = {"read": load_file}
        self.t("read('file.txt')", "42")

        # and we should have *replaced* the default functions. Let's check:

        with self.assertRaises(simpleeval.FunctionNotDefined):
            self.t("int(read('file.txt'))", 42)

        # OK, so we can load in the default functions as well...

        self.s.functions.update(simpleeval.DEFAULT_FUNCTIONS)

        # now it works:

        self.t("int(read('file.txt'))", 42)

    def test_randoms(self):
        ''' test the rand() and randint() functions '''

        self.s.functions['type'] = type

        self.t('type(randint(1000))', int)
        self.t('type(rand())', float)

        self.t("randint(20)<20", True)
        self.t("rand()<1.0", True)

        # I don't know how to further test these functions.  Ideas?

class TestOperators(DRYTest):
    ''' Test adding in new operators, removing them, make sure it works. '''
    pass

class TestTryingToBreakOut(DRYTest):
    ''' Test various weird methods to break the security sandbox... '''

    def test_import(self):
        ''' usual suspect. import '''
        # cannot import things:
        with self.assertRaises(AttributeError):
            self.t("import sys", None)

    def test_long_running(self):
        ''' exponent operations can take a long time. '''
        old_max = simpleeval.MAX_POWER

        self.t("9**9**5", 9**9**5)

        with self.assertRaises(simpleeval.NumberTooHigh):
            self.t("9**9**8", 0)

        # and does limiting work?

        simpleeval.MAX_POWER = 100

        with self.assertRaises(simpleeval.NumberTooHigh):
            self.t("101**2", 0)

        # good, so set it back:

        simpleeval.MAX_POWER = old_max

    def test_string_length(self):

        with self.assertRaises(simpleeval.StringTooLong):
            self.t("50000*'text'", 0)

        with self.assertRaises(simpleeval.StringTooLong):
            self.t("'text'*50000", 0)

        with self.assertRaises(simpleeval.StringTooLong):
            self.t("('text'*50000)*1000", 0)

        with self.assertRaises(simpleeval.StringTooLong):
            self.t("(50000*'text')*1000", 0)

        self.t("'stuff'*20000", 20000*'stuff')

        self.t("20000*'stuff'", 20000*'stuff')

        with self.assertRaises(simpleeval.StringTooLong):
            self.t("('stuff'*20000) + ('stuff'*20000) ", 0)

        with self.assertRaises(simpleeval.StringTooLong):
            self.t("'stuff'*100000", 100000*'stuff')

        with self.assertRaises(simpleeval.StringTooLong):
            self.t("'" + (10000*"stuff") +"'*100", 0)

        with self.assertRaises(simpleeval.StringTooLong):
            self.t("'" + (50000 * "stuff") + "'", 0)

    def test_python_stuff(self):
        ''' other various pythony things. '''
        # it only evaluates the first statement:
        self.t("a = 11; x = 21; x + x", 11)

        # list comprehensions don't work:
        # this could be changed in a future release, if people want...
        with self.assertRaises(simpleeval.FeatureNotAvailable):
            self.t("[x for x in (1, 2, 3)]", (1, 2, 3))

class TestNames(DRYTest):
    ''' 'names', what other languages call variables... '''

    def test_none(self):
        ''' what to do when names isn't defined, or is 'none' '''
        with self.assertRaises(NameNotDefined):
            self.t("a == 2", None)

        self.s.names["s"] = 21

        with self.assertRaises(NameNotDefined):
            self.t("s += a", 21)

        self.s.names = None

        with self.assertRaises(InvalidExpression):
            self.t('s', 21)

        self.s.names = {'a' : {'b': {'c': 42}}}

        with self.assertRaises(AttributeDoesNotExist):
            self.t('a.b.d**2', 42)


    def test_dict(self):
        ''' using a normal dict for names lookup '''

        self.s.names = {'a': 42}
        self.t("a + a", 84)

        self.s.names['also'] = 100

        self.t("a + also - a", 100)

        # however, you can't assign to those names:

        self.t("a = 200", 200)

        self.assertEqual(self.s.names['a'], 42)

        # or assign to lists

        self.s.names['b'] = [0]

        self.t("b[0] = 11", 11)

        self.assertEqual(self.s.names['b'], [0])

        # but you can get items from a list:

        self.s.names['b'] = [6, 7]

        self.t("b[0] * b[1]", 42)

        # or from a dict

        self.s.names['c'] = {'i': 11}

        self.t("c['i']", 11)

        # you still can't assign though:

        self.t("c['b'] = 99", 99)

        self.assertFalse('b' in self.s.names['c'])

        # and going all 'inception' on it doesn't work either:

        self.s.names['c']['c'] = {'c': 11}

        self.t("c['c']['c'] = 21", 21)

        self.assertEqual(self.s.names['c']['c']['c'], 11)

        # nested dict

        self.s.names = {'a' : {'b': {'c': 42}}}

        self.t("a.b.c*2", 84)

        self.t("a.b.c = 11", 11)

        self.assertEqual(self.s.names['a']['b']['c'], 42)

        self.t("a.d = 11", 11)

        with self.assertRaises(KeyError):
            self.assertEqual(self.s.names['a']['d'], 11)

    def test_func(self):
        ''' using a function for 'names lookup' '''

        def resolver(node): # pylint: disable=unused-argument
            ''' all names now equal 1024! '''
            return 1024

        self.s.names = resolver

        self.t("a", 1024)
        self.t("a + b - c - d", 0)

        # the function can do stuff with the value it's sent:

        def my_name(node):
            ''' all names equal their textual name, twice. '''
            return node.id + node.id

        self.s.names = my_name

        self.t("a", "aa")

    def test_from_doc(self):
        ''' the 'name first letter as value' example from the docs '''

        def name_handler(node):
            ''' return the alphabet number of the first letter of
                the name's textual name '''
            return ord(node.id[0].lower())-96

        self.s.names = name_handler
        self.t('a', 1)
        self.t('a + b', 3)

class Test_simple_eval(unittest.TestCase):
    ''' test the 'simple_eval' wrapper function '''
    def test_basic_run(self):
        self.assertEqual(simple_eval('6*7'), 42)

    def test_default_functions(self):
        self.assertEqual(simple_eval('rand() < 1.0 and rand() > -0.01'), True)
        self.assertEqual(simple_eval('randint(200) < 200 and rand() > 0'), True)

if __name__ == '__main__':
    unittest.main()