Fix for python2.7

listcomp leaks the target and async isn't a thing

Author: dflook

src/python_minifier/transforms/remove_explicit_return_none.py

@@ -4,40 +4,35 @@
 from python_minifier.transforms.suite_transformer import SuiteTransformer
 from python_minifier.util import is_ast_node
 
+
 class RemoveExplicitReturnNone(SuiteTransformer):
     def __call__(self, node):
         return self.visit(node)
 
     def visit_Return(self, node):
         assert isinstance(node, ast.Return)
 
-        # Remove an explicit `return None`
+        # Transform `return None` -> `return`
 
-        if sys.version_info < (3, 4) and is_ast_node(node.value, 'Name') and node.value.id == 'None':
-            # explicit return None
+        if sys.version_info < (3, 4) and isinstance(node.value, ast.Name) and node.value.id == 'None':
             node.value = None
 
         elif sys.version_info >= (3, 4) and is_ast_node(node.value, 'NameConstant') and node.value.value is None:
-            # explicit return None
             node.value = None
 
         return node
 
     def visit_FunctionDef(self, node):
         assert is_ast_node(node, (ast.FunctionDef, 'AsyncFunctionDef'))
 
-        node.body = [self.visit(node) for node in node.body]
-
-        # Remove an explicit `return` from the end of a function
+        node.body = [self.visit(a) for a in node.body]
 
+        # Remove an explicit valueless `return` from the end of a function
         if len(node.body) > 0 and isinstance(node.body[-1], ast.Return) and node.body[-1].value is None:
-            # explicit return None
             node.body.pop()
 
+        # Replace empty suites with `0` expression statements
         if len(node.body) == 0:
             node.body = [self.add_child(ast.Expr(value=ast.Num(0)), parent=node)]
 
         return node
-
-    def visit_AsyncFunctionDef(self, node):
-        return self.visit_FunctionDef(node)

test/test_remove_explicit_return_none.py

@@ -1,4 +1,8 @@
 import ast
+import sys
+
+import pytest
+
 from python_minifier import unparse
 from python_minifier.ast_compare import compare_ast
 from python_minifier.transforms.remove_explicit_return_none import RemoveExplicitReturnNone
@@ -9,6 +13,7 @@ def remove_return_none(source):
 
     return RemoveExplicitReturnNone()(module)
 
+
 def test_trailing_remove_return_none():
     source = 'def a():a=4;return None'
     expected = 'def a():a=4'
@@ -19,6 +24,7 @@ def test_trailing_remove_return_none():
 
     assert unparse(actual_ast) == expected
 
+
 def test_trailing_implicit_return_none():
     source = 'def a():a=4;return'
     expected = 'def a():a=4'
@@ -38,6 +44,7 @@ def test_trailing_remove_return_none_empty_suite():
 
     assert unparse(actual_ast) == expected
 
+
 def test_trailing_implicit_return_none_empty_suite():
     source = 'def a():return'
     expected = 'def a():0'
@@ -46,6 +53,7 @@ def test_trailing_implicit_return_none_empty_suite():
     compare_ast(expected_ast, actual_ast)
     assert unparse(actual_ast) == expected
 
+
 def test_trailing_return_value_unchanged():
     source = 'def a():return 0'
     expected = source
@@ -54,6 +62,7 @@ def test_trailing_return_value_unchanged():
     compare_ast(expected_ast, actual_ast)
     assert unparse(actual_ast) == expected
 
+
 def test_remove_return_none():
     source = '''
 def a():
@@ -68,6 +77,7 @@ def a():
 
     assert unparse(actual_ast) == expected
 
+
 def test_implicit_return_none():
     source = '''
 def a():
@@ -80,6 +90,7 @@ def a():
     compare_ast(expected_ast, actual_ast)
     assert unparse(actual_ast) == expected
 
+
 def test_return_value_unchanged():
     source = '''
 def a():
@@ -92,7 +103,11 @@ def a():
     compare_ast(expected_ast, actual_ast)
     assert unparse(actual_ast) == expected
 
+
 def test_async_trailing_remove_return_none():
+    if sys.version_info < (3, 5):
+        pytest.skip('Async not allowed in python < 3.5')
+
     source = 'async def a():a=4;return None'
     expected = 'async def a():a=4'
 
@@ -102,7 +117,11 @@ def test_async_trailing_remove_return_none():
 
     assert unparse(actual_ast) == expected
 
+
 def test_async_trailing_implicit_return_none():
+    if sys.version_info < (3, 5):
+        pytest.skip('Async not allowed in python < 3.5')
+
     source = 'async def a():a=4;return'
     expected = 'async def a():a=4'
     expected_ast = ast.parse(expected)
@@ -112,6 +131,9 @@ def test_async_trailing_implicit_return_none():
 
 
 def test_async_trailing_remove_return_none_empty_suite():
+    if sys.version_info < (3, 5):
+        pytest.skip('Async not allowed in python < 3.5')
+
     source = 'async def a():return None'
     expected = 'async def a():0'
 
@@ -121,23 +143,35 @@ def test_async_trailing_remove_return_none_empty_suite():
 
     assert unparse(actual_ast) == expected
 
+
 def test_async_trailing_implicit_return_none_empty_suite():
+    if sys.version_info < (3, 5):
+        pytest.skip('Async not allowed in python < 3.5')
+
     source = 'async def a():return'
     expected = 'async def a():0'
     expected_ast = ast.parse(expected)
     actual_ast = remove_return_none(source)
     compare_ast(expected_ast, actual_ast)
     assert unparse(actual_ast) == expected
 
+
 def test_async_trailing_return_value_unchanged():
+    if sys.version_info < (3, 5):
+        pytest.skip('Async not allowed in python < 3.5')
+
     source = 'async def a():return 0'
     expected = source
     expected_ast = ast.parse(expected)
     actual_ast = remove_return_none(source)
     compare_ast(expected_ast, actual_ast)
     assert unparse(actual_ast) == expected
 
+
 def test_async_remove_return_none():
+    if sys.version_info < (3, 5):
+        pytest.skip('Async not allowed in python < 3.5')
+
     source = '''
 async def a():
     if a: return None
@@ -151,7 +185,11 @@ async def a():
 
     assert unparse(actual_ast) == expected
 
+
 def test_async_implicit_return_none():
+    if sys.version_info < (3, 5):
+        pytest.skip('Async not allowed in python < 3.5')
+
     source = '''
 async def a():
     if a: return
@@ -163,7 +201,11 @@ async def a():
     compare_ast(expected_ast, actual_ast)
     assert unparse(actual_ast) == expected
 
+
 def test_async_return_value_unchanged():
+    if sys.version_info < (3, 5):
+        pytest.skip('Async not allowed in python < 3.5')
+
     source = '''
 async def a():
     if a: return 1