Update Demo/parser/unparse.py to current Python 3.x syntax. Additions:

- relative imports
 - keyword-only arguments
 - function annotations
 - class decorators
 - raise ... from ...
 - except ... as ...
 - nonlocal
 - bytes literals
 - set literals
 - set comprehensions
 - dict comprehensions
Removals:
 - print statement.

Some of this should be backported to 2.x.

Demo/parser/test_unparse.py

@@ -6,7 +6,7 @@ import ast
 import _ast
 import unparse
 
-forelse = """\
+for_else = """\
 def f():
     for x in range(10):
         break
@@ -15,7 +15,7 @@ def f():
     z = 3
 """
 
-whileelse = """\
+while_else = """\
 def g():
     while True:
         break
@@ -24,6 +24,37 @@ def g():
     z = 3
 """
 
+relative_import = """\
+from . import fred
+from .. import barney
+from .australia import shrimp as prawns
+"""
+
+nonlocal_ex = """\
+def f():
+    x = 1
+    def g():
+        nonlocal x
+        x = 2
+        y = 7
+        def h():
+            nonlocal x, y
+"""
+
+# also acts as test for 'except ... as ...'
+raise_from = """\
+try:
+    1 / 0
+except ZeroDivisionError as e:
+    raise ArithmeticError from e
+"""
+
+class_decorator = """\
+@f1(arg)
+@f2
+class Foo: pass
+"""
+
 class UnparseTestCase(unittest.TestCase):
     # Tests for specific bugs found in earlier versions of unparse
 
@@ -43,10 +74,10 @@ class UnparseTestCase(unittest.TestCase):
         self.check_roundtrip("13 >> 7")
 
     def test_for_else(self):
-        self.check_roundtrip(forelse)
+        self.check_roundtrip(for_else)
 
     def test_while_else(self):
-        self.check_roundtrip(whileelse)
+        self.check_roundtrip(while_else)
 
     def test_unary_parens(self):
         self.check_roundtrip("(-1)**7")
@@ -57,6 +88,50 @@ class UnparseTestCase(unittest.TestCase):
         self.check_roundtrip("1 < 4 <= 5")
         self.check_roundtrip("a is b is c is not d")
 
+    def test_function_arguments(self):
+        self.check_roundtrip("def f(): pass")
+        self.check_roundtrip("def f(a): pass")
+        self.check_roundtrip("def f(b = 2): pass")
+        self.check_roundtrip("def f(a, b): pass")
+        self.check_roundtrip("def f(a, b = 2): pass")
+        self.check_roundtrip("def f(a = 5, b = 2): pass")
+        self.check_roundtrip("def f(*, a = 1, b = 2): pass")
+        self.check_roundtrip("def f(*, a = 1, b): pass")
+        self.check_roundtrip("def f(*, a, b = 2): pass")
+        self.check_roundtrip("def f(a, b = None, *, c, **kwds): pass")
+        self.check_roundtrip("def f(a=2, *args, c=5, d, **kwds): pass")
+        self.check_roundtrip("def f(*args, **kwargs): pass")
+
+    def test_relative_import(self):
+        self.check_roundtrip(relative_import)
+
+    def test_nonlocal(self):
+        self.check_roundtrip(nonlocal_ex)
+
+    def test_raise_from(self):
+        self.check_roundtrip(raise_from)
+
+    def test_bytes(self):
+        self.check_roundtrip("b'123'")
+
+    def test_annotations(self):
+        self.check_roundtrip("def f(a : int): pass")
+        self.check_roundtrip("def f(a: int = 5): pass")
+        self.check_roundtrip("def f(*args: [int]): pass")
+        self.check_roundtrip("def f(**kwargs: dict): pass")
+        self.check_roundtrip("def f() -> None: pass")
+
+    def test_set_literal(self):
+        self.check_roundtrip("{'a', 'b', 'c'}")
+
+    def test_set_comprehension(self):
+        self.check_roundtrip("{x for x in range(5)}")
+
+    def test_dict_comprehension(self):
+        self.check_roundtrip("{x: x*x for x in range(10)}")
+
+    def test_class_decorators(self):
+        self.check_roundtrip(class_decorator)
 
 def test_main():
     test.support.run_unittest(UnparseTestCase)