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	Fix two (in my opinion) spurious failure conditions in the lib2to3.tests.test_parser.TestParserIdempotency test_parser test.
    Use the same encoding found in the initial file to write a temp file for a diff. This retains the BOM if the encoding was initially utf-8-sig.
    If the file cannot be parsed using the normal grammar, try again with no print statement which should succeed for valid files using future print_function
For case (1), the driver was correctly handling a BOM in a utf-8 file, but then the test was not writing a comparison file using 'utf-8-sig' to diff against, so the BOM got removed. I don't think that is the fault of the parser, and lib2to3 will retain the BOM.
For case (2), lib2to3 pre-detects the use of from __future__ import print_function or allows the user to force this interpretation with a -p flag, and then selects a different grammar with the print statement removed. That makes the test cases unfair to this test as the driver itself doesn't know which grammar to use. As a minimal fix, the test will try using a grammar with the print statement, and if that fails fall back on a grammar without it. A more thorough handling of the idempotency test would to be to parse all files using both grammars and ignore if one of the two failed but otherwise check both. I didn't think this was necessary but can change.
		
	
			
		
			
				
	
	
		
			58 lines
		
	
	
	
		
			1.9 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
			
		
		
	
	
			58 lines
		
	
	
	
		
			1.9 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
"""Support code for test_*.py files"""
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# Author: Collin Winter
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# Python imports
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import unittest
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import os
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import os.path
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from textwrap import dedent
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# Local imports
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from lib2to3 import pytree, refactor
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from lib2to3.pgen2 import driver as pgen2_driver
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test_dir = os.path.dirname(__file__)
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proj_dir = os.path.normpath(os.path.join(test_dir, ".."))
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grammar_path = os.path.join(test_dir, "..", "Grammar.txt")
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grammar = pgen2_driver.load_grammar(grammar_path)
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grammar_no_print_statement = pgen2_driver.load_grammar(grammar_path)
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del grammar_no_print_statement.keywords["print"]
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driver = pgen2_driver.Driver(grammar, convert=pytree.convert)
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driver_no_print_statement = pgen2_driver.Driver(
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    grammar_no_print_statement,
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    convert=pytree.convert
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)
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def parse_string(string):
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    return driver.parse_string(reformat(string), debug=True)
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def run_all_tests(test_mod=None, tests=None):
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    if tests is None:
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        tests = unittest.TestLoader().loadTestsFromModule(test_mod)
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    unittest.TextTestRunner(verbosity=2).run(tests)
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def reformat(string):
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    return dedent(string) + "\n\n"
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def get_refactorer(fixer_pkg="lib2to3", fixers=None, options=None):
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    """
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    A convenience function for creating a RefactoringTool for tests.
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    fixers is a list of fixers for the RefactoringTool to use. By default
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    "lib2to3.fixes.*" is used. options is an optional dictionary of options to
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    be passed to the RefactoringTool.
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    """
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    if fixers is not None:
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        fixers = [fixer_pkg + ".fixes.fix_" + fix for fix in fixers]
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    else:
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        fixers = refactor.get_fixers_from_package(fixer_pkg + ".fixes")
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    options = options or {}
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    return refactor.RefactoringTool(fixers, options, explicit=True)
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def all_project_files():
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    for dirpath, dirnames, filenames in os.walk(proj_dir):
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        for filename in filenames:
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            if filename.endswith(".py"):
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                yield os.path.join(dirpath, filename)
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TestCase = unittest.TestCase
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