bpo-38870: Expose a function to unparse an ast object in the ast module (GH-17302)
Add ast.unparse() as a function in the ast module that can be used to unparse an
ast.AST object and produce a string with code that would produce an equivalent ast.AST
object when parsed.
diff --git a/Lib/test/test_tools/test_unparse.py b/Lib/test/test_unparse.py
similarity index 76%
rename from Lib/test/test_tools/test_unparse.py
rename to Lib/test/test_unparse.py
index a958ebb..9197c8a 100644
--- a/Lib/test/test_tools/test_unparse.py
+++ b/Lib/test/test_unparse.py
@@ -3,19 +3,12 @@
import unittest
import test.support
import io
-import os
+import pathlib
import random
import tokenize
import ast
+import functools
-from test.test_tools import basepath, toolsdir, skip_if_missing
-
-skip_if_missing()
-
-parser_path = os.path.join(toolsdir, "parser")
-
-with test.support.DirsOnSysPath(parser_path):
- import unparse
def read_pyfile(filename):
"""Read and return the contents of a Python source file (as a
@@ -26,6 +19,7 @@
source = pyfile.read()
return source
+
for_else = """\
def f():
for x in range(10):
@@ -119,18 +113,21 @@
suite1
"""
+
class ASTTestCase(unittest.TestCase):
def assertASTEqual(self, ast1, ast2):
self.assertEqual(ast.dump(ast1), ast.dump(ast2))
- def check_roundtrip(self, code1, filename="internal"):
- ast1 = compile(code1, filename, "exec", ast.PyCF_ONLY_AST)
- unparse_buffer = io.StringIO()
- unparse.Unparser(ast1, unparse_buffer)
- code2 = unparse_buffer.getvalue()
- ast2 = compile(code2, filename, "exec", ast.PyCF_ONLY_AST)
+ def check_roundtrip(self, code1):
+ ast1 = ast.parse(code1)
+ code2 = ast.unparse(ast1)
+ ast2 = ast.parse(code2)
self.assertASTEqual(ast1, ast2)
+ def check_invalid(self, node, raises=ValueError):
+ self.assertRaises(raises, ast.unparse, node)
+
+
class UnparseTestCase(ASTTestCase):
# Tests for specific bugs found in earlier versions of unparse
@@ -174,8 +171,8 @@
self.check_roundtrip("-1e1000j")
def test_min_int(self):
- self.check_roundtrip(str(-2**31))
- self.check_roundtrip(str(-2**63))
+ self.check_roundtrip(str(-(2 ** 31)))
+ self.check_roundtrip(str(-(2 ** 63)))
def test_imaginary_literals(self):
self.check_roundtrip("7j")
@@ -265,54 +262,67 @@
self.check_roundtrip(r"""{**{'y': 2}, 'x': 1}""")
self.check_roundtrip(r"""{**{'y': 2}, **{'x': 1}}""")
+ def test_invalid_raise(self):
+ self.check_invalid(ast.Raise(exc=None, cause=ast.Name(id="X")))
+
+ def test_invalid_fstring_constant(self):
+ self.check_invalid(ast.JoinedStr(values=[ast.Constant(value=100)]))
+
+ def test_invalid_fstring_conversion(self):
+ self.check_invalid(
+ ast.FormattedValue(
+ value=ast.Constant(value="a", kind=None),
+ conversion=ord("Y"), # random character
+ format_spec=None,
+ )
+ )
+
+ def test_invalid_set(self):
+ self.check_invalid(ast.Set(elts=[]))
+
class DirectoryTestCase(ASTTestCase):
"""Test roundtrip behaviour on all files in Lib and Lib/test."""
- NAMES = None
- # test directories, relative to the root of the distribution
- test_directories = 'Lib', os.path.join('Lib', 'test')
+ lib_dir = pathlib.Path(__file__).parent / ".."
+ test_directories = (lib_dir, lib_dir / "test")
+ skip_files = {"test_fstring.py"}
- @classmethod
- def get_names(cls):
- if cls.NAMES is not None:
- return cls.NAMES
+ @functools.cached_property
+ def files_to_test(self):
+ # bpo-31174: Use cached_property to store the names sample
+ # to always test the same files. It prevents false alarms
+ # when hunting reference leaks.
- names = []
- for d in cls.test_directories:
- test_dir = os.path.join(basepath, d)
- for n in os.listdir(test_dir):
- if n.endswith('.py') and not n.startswith('bad'):
- names.append(os.path.join(test_dir, n))
+ items = [
+ item.resolve()
+ for directory in self.test_directories
+ for item in directory.glob("*.py")
+ if not item.name.startswith("bad")
+ ]
# Test limited subset of files unless the 'cpu' resource is specified.
if not test.support.is_resource_enabled("cpu"):
- names = random.sample(names, 10)
- # bpo-31174: Store the names sample to always test the same files.
- # It prevents false alarms when hunting reference leaks.
- cls.NAMES = names
- return names
+ items = random.sample(items, 10)
+ return items
def test_files(self):
- # get names of files to test
- names = self.get_names()
-
- for filename in names:
+ for item in self.files_to_test:
if test.support.verbose:
- print('Testing %s' % filename)
+ print(f"Testing {item.absolute()}")
# Some f-strings are not correctly round-tripped by
- # Tools/parser/unparse.py. See issue 28002 for details.
- # We need to skip files that contain such f-strings.
- if os.path.basename(filename) in ('test_fstring.py', ):
+ # Tools/parser/unparse.py. See issue 28002 for details.
+ # We need to skip files that contain such f-strings.
+ if item.name in self.skip_files:
if test.support.verbose:
- print(f'Skipping {filename}: see issue 28002')
+ print(f"Skipping {item.absolute()}: see issue 28002")
continue
- with self.subTest(filename=filename):
- source = read_pyfile(filename)
+ with self.subTest(filename=item):
+ source = read_pyfile(item)
self.check_roundtrip(source)
-if __name__ == '__main__':
+if __name__ == "__main__":
unittest.main()