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1import unittest
2import sys
3from io import StringIO
4
5from test import support
6
7NotDefined = object()
8
9# A dispatch table all 8 combinations of providing
10# sep, end, and file.
11# I use this machinery so that I'm not just passing default
12# values to print, I'm either passing or not passing in the
13# arguments.
14dispatch = {
15    (False, False, False):
16        lambda args, sep, end, file: print(*args),
17    (False, False, True):
18        lambda args, sep, end, file: print(file=file, *args),
19    (False, True,  False):
20        lambda args, sep, end, file: print(end=end, *args),
21    (False, True,  True):
22        lambda args, sep, end, file: print(end=end, file=file, *args),
23    (True,  False, False):
24        lambda args, sep, end, file: print(sep=sep, *args),
25    (True,  False, True):
26        lambda args, sep, end, file: print(sep=sep, file=file, *args),
27    (True,  True,  False):
28        lambda args, sep, end, file: print(sep=sep, end=end, *args),
29    (True,  True,  True):
30        lambda args, sep, end, file: print(sep=sep, end=end, file=file, *args),
31}
32
33
34# Class used to test __str__ and print
35class ClassWith__str__:
36    def __init__(self, x):
37        self.x = x
38
39    def __str__(self):
40        return self.x
41
42
43class TestPrint(unittest.TestCase):
44    """Test correct operation of the print function."""
45
46    def check(self, expected, args,
47              sep=NotDefined, end=NotDefined, file=NotDefined):
48        # Capture sys.stdout in a StringIO.  Call print with args,
49        # and with sep, end, and file, if they're defined.  Result
50        # must match expected.
51
52        # Look up the actual function to call, based on if sep, end,
53        # and file are defined.
54        fn = dispatch[(sep is not NotDefined,
55                       end is not NotDefined,
56                       file is not NotDefined)]
57
58        with support.captured_stdout() as t:
59            fn(args, sep, end, file)
60
61        self.assertEqual(t.getvalue(), expected)
62
63    def test_print(self):
64        def x(expected, args, sep=NotDefined, end=NotDefined):
65            # Run the test 2 ways: not using file, and using
66            # file directed to a StringIO.
67
68            self.check(expected, args, sep=sep, end=end)
69
70            # When writing to a file, stdout is expected to be empty
71            o = StringIO()
72            self.check('', args, sep=sep, end=end, file=o)
73
74            # And o will contain the expected output
75            self.assertEqual(o.getvalue(), expected)
76
77        x('\n', ())
78        x('a\n', ('a',))
79        x('None\n', (None,))
80        x('1 2\n', (1, 2))
81        x('1   2\n', (1, ' ', 2))
82        x('1*2\n', (1, 2), sep='*')
83        x('1 s', (1, 's'), end='')
84        x('a\nb\n', ('a', 'b'), sep='\n')
85        x('1.01', (1.0, 1), sep='', end='')
86        x('1*a*1.3+', (1, 'a', 1.3), sep='*', end='+')
87        x('a\n\nb\n', ('a\n', 'b'), sep='\n')
88        x('\0+ +\0\n', ('\0', ' ', '\0'), sep='+')
89
90        x('a\n b\n', ('a\n', 'b'))
91        x('a\n b\n', ('a\n', 'b'), sep=None)
92        x('a\n b\n', ('a\n', 'b'), end=None)
93        x('a\n b\n', ('a\n', 'b'), sep=None, end=None)
94
95        x('*\n', (ClassWith__str__('*'),))
96        x('abc 1\n', (ClassWith__str__('abc'), 1))
97
98        # errors
99        self.assertRaises(TypeError, print, '', sep=3)
100        self.assertRaises(TypeError, print, '', end=3)
101        self.assertRaises(AttributeError, print, '', file='')
102
103    def test_print_flush(self):
104        # operation of the flush flag
105        class filelike:
106            def __init__(self):
107                self.written = ''
108                self.flushed = 0
109
110            def write(self, str):
111                self.written += str
112
113            def flush(self):
114                self.flushed += 1
115
116        f = filelike()
117        print(1, file=f, end='', flush=True)
118        print(2, file=f, end='', flush=True)
119        print(3, file=f, flush=False)
120        self.assertEqual(f.written, '123\n')
121        self.assertEqual(f.flushed, 2)
122
123        # ensure exceptions from flush are passed through
124        class noflush:
125            def write(self, str):
126                pass
127
128            def flush(self):
129                raise RuntimeError
130        self.assertRaises(RuntimeError, print, 1, file=noflush(), flush=True)
131
132
133class TestPy2MigrationHint(unittest.TestCase):
134    """Test that correct hint is produced analogous to Python3 syntax,
135    if print statement is executed as in Python 2.
136    """
137
138    def test_normal_string(self):
139        python2_print_str = 'print "Hello World"'
140        with self.assertRaises(SyntaxError) as context:
141            exec(python2_print_str)
142
143        self.assertIn('print("Hello World")', str(context.exception))
144
145    def test_string_with_soft_space(self):
146        python2_print_str = 'print "Hello World",'
147        with self.assertRaises(SyntaxError) as context:
148            exec(python2_print_str)
149
150        self.assertIn('print("Hello World", end=" ")', str(context.exception))
151
152    def test_string_with_excessive_whitespace(self):
153        python2_print_str = 'print  "Hello World", '
154        with self.assertRaises(SyntaxError) as context:
155            exec(python2_print_str)
156
157        self.assertIn('print("Hello World", end=" ")', str(context.exception))
158
159    def test_string_with_leading_whitespace(self):
160        python2_print_str = '''if 1:
161            print "Hello World"
162        '''
163        with self.assertRaises(SyntaxError) as context:
164            exec(python2_print_str)
165
166        self.assertIn('print("Hello World")', str(context.exception))
167
168    # bpo-32685: Suggestions for print statement should be proper when
169    # it is in the same line as the header of a compound statement
170    # and/or followed by a semicolon
171    def test_string_with_semicolon(self):
172        python2_print_str = 'print p;'
173        with self.assertRaises(SyntaxError) as context:
174            exec(python2_print_str)
175
176        self.assertIn('print(p)', str(context.exception))
177
178    def test_string_in_loop_on_same_line(self):
179        python2_print_str = 'for i in s: print i'
180        with self.assertRaises(SyntaxError) as context:
181            exec(python2_print_str)
182
183        self.assertIn('print(i)', str(context.exception))
184
185    def test_stream_redirection_hint_for_py2_migration(self):
186        # Test correct hint produced for Py2 redirection syntax
187        with self.assertRaises(TypeError) as context:
188            print >> sys.stderr, "message"
189        self.assertIn('Did you mean "print(<message>, '
190                'file=<output_stream>)"?', str(context.exception))
191
192        # Test correct hint is produced in the case where RHS implements
193        # __rrshift__ but returns NotImplemented
194        with self.assertRaises(TypeError) as context:
195            print >> 42
196        self.assertIn('Did you mean "print(<message>, '
197                'file=<output_stream>)"?', str(context.exception))
198
199        # Test stream redirection hint is specific to print
200        with self.assertRaises(TypeError) as context:
201            max >> sys.stderr
202        self.assertNotIn('Did you mean ', str(context.exception))
203
204        # Test stream redirection hint is specific to rshift
205        with self.assertRaises(TypeError) as context:
206            print << sys.stderr
207        self.assertNotIn('Did you mean', str(context.exception))
208
209        # Ensure right operand implementing rrshift still works
210        class OverrideRRShift:
211            def __rrshift__(self, lhs):
212                return 42 # Force result independent of LHS
213
214        self.assertEqual(print >> OverrideRRShift(), 42)
215
216
217
218if __name__ == "__main__":
219    unittest.main()
220