cpython/Lib/test/test_future.py

# Test various flavors of legal and illegal future statements

import unittest
from test import support
import re

rx = re.compile(r'\((\S+).py, line (\d+)')

def get_error_location(msg):
    mo = rx.search(str(msg))
    return mo.group(1, 2)

class FutureTest(unittest.TestCase):

    def test_future1(self):
        with support.CleanImport('future_test1'):
            from test import future_test1
            self.assertEqual(future_test1.result, 6)

    def test_future2(self):
        with support.CleanImport('future_test2'):
            from test import future_test2
            self.assertEqual(future_test2.result, 6)

    def test_future3(self):
        with support.CleanImport('test_future3'):
            from test import test_future3

    def test_badfuture3(self):
        try:
            from test import badsyntax_future3
        except SyntaxError as msg:
            self.assertEqual(get_error_location(msg), ("badsyntax_future3", '3'))
        else:
            self.fail("expected exception didn't occur")

    def test_badfuture4(self):
        try:
            from test import badsyntax_future4
        except SyntaxError as msg:
            self.assertEqual(get_error_location(msg), ("badsyntax_future4", '3'))
        else:
            self.fail("expected exception didn't occur")

    def test_badfuture5(self):
        try:
            from test import badsyntax_future5
        except SyntaxError as msg:
            self.assertEqual(get_error_location(msg), ("badsyntax_future5", '4'))
        else:
            self.fail("expected exception didn't occur")

    def test_badfuture6(self):
        try:
            from test import badsyntax_future6
        except SyntaxError as msg:
            self.assertEqual(get_error_location(msg), ("badsyntax_future6", '3'))
        else:
            self.fail("expected exception didn't occur")

    def test_badfuture7(self):
        try:
            from test import badsyntax_future7
        except SyntaxError as msg:
            self.assertEqual(get_error_location(msg), ("badsyntax_future7", '3'))
        else:
            self.fail("expected exception didn't occur")

    def test_badfuture8(self):
        try:
            from test import badsyntax_future8
        except SyntaxError as msg:
            self.assertEqual(get_error_location(msg), ("badsyntax_future8", '3'))
        else:
            self.fail("expected exception didn't occur")

    def test_badfuture9(self):
        try:
            from test import badsyntax_future9
        except SyntaxError as msg:
            self.assertEqual(get_error_location(msg), ("badsyntax_future9", '3'))
        else:
            self.fail("expected exception didn't occur")

    def test_badfuture10(self):
        try:
            from test import badsyntax_future10
        except SyntaxError as msg:
            self.assertEqual(get_error_location(msg), ("badsyntax_future10", '3'))
        else:
            self.fail("expected exception didn't occur")

    def test_parserhack(self):
        # test that the parser.c::future_hack function works as expected
        # Note: although this test must pass, it's not testing the original
        #       bug as of 2.6 since the with statement is not optional and
        #       the parser hack disabled. If a new keyword is introduced in
        #       2.6, change this to refer to the new future import.
        try:
            exec("from __future__ import print_function; print 0")
        except SyntaxError:
            pass
        else:
            self.fail("syntax error didn't occur")

        try:
            exec("from __future__ import (print_function); print 0")
        except SyntaxError:
            pass
        else:
            self.fail("syntax error didn't occur")

    def test_multiple_features(self):
        with support.CleanImport("test.test_future5"):
            from test import test_future5

    def test_unicode_literals_exec(self):
        scope = {}
        exec("from __future__ import unicode_literals; x = ''", {}, scope)
        self.assertIsInstance(scope["x"], str)



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