Home | History | Annotate | Download | only in test 
      1 """Test correct operation of the print function.
      2 """
      3 
      4 # In 2.6, this gives us the behavior we want.  In 3.0, it has
      5 #  no function, but it still must parse correctly.
      6 from __future__ import print_function
      7 
      8 import unittest
      9 from test import test_support
     10 
     11 from StringIO import StringIO
     12 
     13 NotDefined = object()
     14 
     15 # A dispatch table all 8 combinations of providing
     16 #  sep, end, and file
     17 # I use this machinery so that I'm not just passing default
     18 #  values to print, I'm either passing or not passing in the
     19 #  arguments
     20 dispatch = {
     21     (False, False, False):
     22      lambda args, sep, end, file: print(*args),
     23     (False, False, True):
     24      lambda args, sep, end, file: print(file=file, *args),
     25     (False, True,  False):
     26      lambda args, sep, end, file: print(end=end, *args),
     27     (False, True,  True):
     28      lambda args, sep, end, file: print(end=end, file=file, *args),
     29     (True,  False, False):
     30      lambda args, sep, end, file: print(sep=sep, *args),
     31     (True,  False, True):
     32      lambda args, sep, end, file: print(sep=sep, file=file, *args),
     33     (True,  True,  False):
     34      lambda args, sep, end, file: print(sep=sep, end=end, *args),
     35     (True,  True,  True):
     36      lambda args, sep, end, file: print(sep=sep, end=end, file=file, *args),
     37     }
     38 
     39 # Class used to test __str__ and print
     40 class ClassWith__str__:
     41     def __init__(self, x):
     42         self.x = x
     43     def __str__(self):
     44         return self.x
     45 
     46 class TestPrint(unittest.TestCase):
     47     def check(self, expected, args,
     48             sep=NotDefined, end=NotDefined, file=NotDefined):
     49         # Capture sys.stdout in a StringIO.  Call print with args,
     50         #  and with sep, end, and file, if they're defined.  Result
     51         #  must match expected.
     52 
     53         # Look up the actual function to call, based on if sep, end, and file
     54         #  are defined
     55         fn = dispatch[(sep is not NotDefined,
     56                        end is not NotDefined,
     57                        file is not NotDefined)]
     58 
     59         with test_support.captured_stdout() as t:
     60             fn(args, sep, end, file)
     61 
     62         self.assertEqual(t.getvalue(), expected)
     63 
     64     def test_print(self):
     65         def x(expected, args, sep=NotDefined, end=NotDefined):
     66             # Run the test 2 ways: not using file, and using
     67             #  file directed to a StringIO
     68 
     69             self.check(expected, args, sep=sep, end=end)
     70 
     71             # When writing to a file, stdout is expected to be empty
     72             o = StringIO()
     73             self.check('', args, sep=sep, end=end, file=o)
     74 
     75             # And o will contain the expected output
     76             self.assertEqual(o.getvalue(), expected)
     77 
     78         x('\n', ())
     79         x('a\n', ('a',))
     80         x('None\n', (None,))
     81         x('1 2\n', (1, 2))
     82         x('1   2\n', (1, ' ', 2))
     83         x('1*2\n', (1, 2), sep='*')
     84         x('1 s', (1, 's'), end='')
     85         x('a\nb\n', ('a', 'b'), sep='\n')
     86         x('1.01', (1.0, 1), sep='', end='')
     87         x('1*a*1.3+', (1, 'a', 1.3), sep='*', end='+')
     88         x('a\n\nb\n', ('a\n', 'b'), sep='\n')
     89         x('\0+ +\0\n', ('\0', ' ', '\0'), sep='+')
     90 
     91         x('a\n b\n', ('a\n', 'b'))
     92         x('a\n b\n', ('a\n', 'b'), sep=None)
     93         x('a\n b\n', ('a\n', 'b'), end=None)
     94         x('a\n b\n', ('a\n', 'b'), sep=None, end=None)
     95 
     96         x('*\n', (ClassWith__str__('*'),))
     97         x('abc 1\n', (ClassWith__str__('abc'), 1))
     98 
     99         # 2.x unicode tests
    100         x(u'1 2\n', ('1', u'2'))
    101         x(u'u\1234\n', (u'u\1234',))
    102         x(u'  abc 1\n', (' ', ClassWith__str__(u'abc'), 1))
    103 
    104         # errors
    105         self.assertRaises(TypeError, print, '', sep=3)
    106         self.assertRaises(TypeError, print, '', end=3)
    107         self.assertRaises(AttributeError, print, '', file='')
    108 
    109     def test_mixed_args(self):
    110         # If a unicode arg is passed, sep and end should be unicode, too.
    111         class Recorder(object):
    112 
    113             def __init__(self, must_be_unicode):
    114                 self.buf = []
    115                 self.force_unicode = must_be_unicode
    116 
    117             def write(self, what):
    118                 if self.force_unicode and not isinstance(what, unicode):
    119                     raise AssertionError("{0!r} is not unicode".format(what))
    120                 self.buf.append(what)
    121 
    122         buf = Recorder(True)
    123         print(u'hi', file=buf)
    124         self.assertEqual(u''.join(buf.buf), 'hi\n')
    125         del buf.buf[:]
    126         print(u'hi', u'nothing', file=buf)
    127         self.assertEqual(u''.join(buf.buf), 'hi nothing\n')
    128         buf = Recorder(False)
    129         print('hi', 'bye', end=u'\n', file=buf)
    130         self.assertIsInstance(buf.buf[1], unicode)
    131         self.assertIsInstance(buf.buf[3], unicode)
    132         del buf.buf[:]
    133         print(sep=u'x', file=buf)
    134         self.assertIsInstance(buf.buf[-1], unicode)
    135 
    136 
    137 def test_main():
    138     test_support.run_unittest(TestPrint)
    139 
    140 if __name__ == "__main__":
    141     test_main()
    142