new test_print.py from cpython v.3.11.2

Author: JaeyoungAhn

Lib/test/test_print.py

@@ -0,0 +1,225 @@
+import unittest
+import sys
+from io import StringIO
+
+from test import support
+
+NotDefined = object()
+
+# A dispatch table all 8 combinations of providing
+# sep, end, and file.
+# I use this machinery so that I'm not just passing default
+# values to print, I'm either passing or not passing in the
+# arguments.
+dispatch = {
+    (False, False, False):
+        lambda args, sep, end, file: print(*args),
+    (False, False, True):
+        lambda args, sep, end, file: print(file=file, *args),
+    (False, True,  False):
+        lambda args, sep, end, file: print(end=end, *args),
+    (False, True,  True):
+        lambda args, sep, end, file: print(end=end, file=file, *args),
+    (True,  False, False):
+        lambda args, sep, end, file: print(sep=sep, *args),
+    (True,  False, True):
+        lambda args, sep, end, file: print(sep=sep, file=file, *args),
+    (True,  True,  False):
+        lambda args, sep, end, file: print(sep=sep, end=end, *args),
+    (True,  True,  True):
+        lambda args, sep, end, file: print(sep=sep, end=end, file=file, *args),
+}
+
+
+# Class used to test __str__ and print
+class ClassWith__str__:
+    def __init__(self, x):
+        self.x = x
+
+    def __str__(self):
+        return self.x
+
+
+class TestPrint(unittest.TestCase):
+    """Test correct operation of the print function."""
+
+    def check(self, expected, args,
+              sep=NotDefined, end=NotDefined, file=NotDefined):
+        # Capture sys.stdout in a StringIO.  Call print with args,
+        # and with sep, end, and file, if they're defined.  Result
+        # must match expected.
+
+        # Look up the actual function to call, based on if sep, end,
+        # and file are defined.
+        fn = dispatch[(sep is not NotDefined,
+                       end is not NotDefined,
+                       file is not NotDefined)]
+
+        with support.captured_stdout() as t:
+            fn(args, sep, end, file)
+
+        self.assertEqual(t.getvalue(), expected)
+
+    def test_print(self):
+        def x(expected, args, sep=NotDefined, end=NotDefined):
+            # Run the test 2 ways: not using file, and using
+            # file directed to a StringIO.
+
+            self.check(expected, args, sep=sep, end=end)
+
+            # When writing to a file, stdout is expected to be empty
+            o = StringIO()
+            self.check('', args, sep=sep, end=end, file=o)
+
+            # And o will contain the expected output
+            self.assertEqual(o.getvalue(), expected)
+
+        x('\n', ())
+        x('a\n', ('a',))
+        x('None\n', (None,))
+        x('1 2\n', (1, 2))
+        x('1   2\n', (1, ' ', 2))
+        x('1*2\n', (1, 2), sep='*')
+        x('1 s', (1, 's'), end='')
+        x('a\nb\n', ('a', 'b'), sep='\n')
+        x('1.01', (1.0, 1), sep='', end='')
+        x('1*a*1.3+', (1, 'a', 1.3), sep='*', end='+')
+        x('a\n\nb\n', ('a\n', 'b'), sep='\n')
+        x('\0+ +\0\n', ('\0', ' ', '\0'), sep='+')
+
+        x('a\n b\n', ('a\n', 'b'))
+        x('a\n b\n', ('a\n', 'b'), sep=None)
+        x('a\n b\n', ('a\n', 'b'), end=None)
+        x('a\n b\n', ('a\n', 'b'), sep=None, end=None)
+
+        x('*\n', (ClassWith__str__('*'),))
+        x('abc 1\n', (ClassWith__str__('abc'), 1))
+
+        # errors
+        self.assertRaises(TypeError, print, '', sep=3)
+        self.assertRaises(TypeError, print, '', end=3)
+        self.assertRaises(AttributeError, print, '', file='')
+
+    def test_print_flush(self):
+        # operation of the flush flag
+        class filelike:
+            def __init__(self):
+                self.written = ''
+                self.flushed = 0
+
+            def write(self, str):
+                self.written += str
+
+            def flush(self):
+                self.flushed += 1
+
+        f = filelike()
+        print(1, file=f, end='', flush=True)
+        print(2, file=f, end='', flush=True)
+        print(3, file=f, flush=False)
+        self.assertEqual(f.written, '123\n')
+        self.assertEqual(f.flushed, 2)
+
+        # ensure exceptions from flush are passed through
+        class noflush:
+            def write(self, str):
+                pass
+
+            def flush(self):
+                raise RuntimeError
+        self.assertRaises(RuntimeError, print, 1, file=noflush(), flush=True)
+
+
+class TestPy2MigrationHint(unittest.TestCase):
+    """Test that correct hint is produced analogous to Python3 syntax,
+    if print statement is executed as in Python 2.
+    """
+
+    def test_normal_string(self):
+        python2_print_str = 'print "Hello World"'
+        with self.assertRaises(SyntaxError) as context:
+            exec(python2_print_str)
+
+        self.assertIn("Missing parentheses in call to 'print'. Did you mean print(...)",
+                str(context.exception))
+
+    def test_string_with_soft_space(self):
+        python2_print_str = 'print "Hello World",'
+        with self.assertRaises(SyntaxError) as context:
+            exec(python2_print_str)
+
+        self.assertIn("Missing parentheses in call to 'print'. Did you mean print(...)",
+                str(context.exception))
+
+    def test_string_with_excessive_whitespace(self):
+        python2_print_str = 'print  "Hello World", '
+        with self.assertRaises(SyntaxError) as context:
+            exec(python2_print_str)
+
+        self.assertIn("Missing parentheses in call to 'print'. Did you mean print(...)",
+                str(context.exception))
+
+    def test_string_with_leading_whitespace(self):
+        python2_print_str = '''if 1:
+            print "Hello World"
+        '''
+        with self.assertRaises(SyntaxError) as context:
+            exec(python2_print_str)
+
+        self.assertIn("Missing parentheses in call to 'print'. Did you mean print(...)",
+                str(context.exception))
+
+    # bpo-32685: Suggestions for print statement should be proper when
+    # it is in the same line as the header of a compound statement
+    # and/or followed by a semicolon
+    def test_string_with_semicolon(self):
+        python2_print_str = 'print p;'
+        with self.assertRaises(SyntaxError) as context:
+            exec(python2_print_str)
+
+        self.assertIn("Missing parentheses in call to 'print'. Did you mean print(...)",
+                str(context.exception))
+
+    def test_string_in_loop_on_same_line(self):
+        python2_print_str = 'for i in s: print i'
+        with self.assertRaises(SyntaxError) as context:
+            exec(python2_print_str)
+
+        self.assertIn("Missing parentheses in call to 'print'. Did you mean print(...)",
+                str(context.exception))
+
+    def test_stream_redirection_hint_for_py2_migration(self):
+        # Test correct hint produced for Py2 redirection syntax
+        with self.assertRaises(TypeError) as context:
+            print >> sys.stderr, "message"
+        self.assertIn('Did you mean "print(<message>, '
+                'file=<output_stream>)"?', str(context.exception))
+
+        # Test correct hint is produced in the case where RHS implements
+        # __rrshift__ but returns NotImplemented
+        with self.assertRaises(TypeError) as context:
+            print >> 42
+        self.assertIn('Did you mean "print(<message>, '
+                'file=<output_stream>)"?', str(context.exception))
+
+        # Test stream redirection hint is specific to print
+        with self.assertRaises(TypeError) as context:
+            max >> sys.stderr
+        self.assertNotIn('Did you mean ', str(context.exception))
+
+        # Test stream redirection hint is specific to rshift
+        with self.assertRaises(TypeError) as context:
+            print << sys.stderr
+        self.assertNotIn('Did you mean', str(context.exception))
+
+        # Ensure right operand implementing rrshift still works
+        class OverrideRRShift:
+            def __rrshift__(self, lhs):
+                return 42 # Force result independent of LHS
+
+        self.assertEqual(print >> OverrideRRShift(), 42)
+
+
+
+if __name__ == "__main__":
+    unittest.main()