Update unparser for py 3.12 and setup minimal testing

Finally fixes #79

gast/unparser.py

@@ -412,6 +412,8 @@ def visit_ClassDef(self, node):
             self.fill("@")
             self.traverse(deco)
         self.fill("class " + node.name)
+        if hasattr(node, "type_params"):
+            self._type_params_helper(node.type_params)
         with self.delimit_if("(", ")", condition = node.bases or node.keywords):
             comma = False
             for e in node.bases:
@@ -443,6 +445,8 @@ def _function_helper(self, node, fill_suffix):
             self.traverse(deco)
         def_str = fill_suffix + " " + node.name
         self.fill(def_str)
+        if hasattr(node, "type_params"):
+            self._type_params_helper(node.type_params)
         with self.delimit("(", ")"):
             self.traverse(node.args)
         if node.returns:
@@ -451,6 +455,30 @@ def _function_helper(self, node, fill_suffix):
         with self.block(extra=self.get_type_comment(node)):
             self._write_docstring_and_traverse_body(node)
 
+    def _type_params_helper(self, type_params):
+        if type_params is not None and len(type_params) > 0:
+            with self.delimit("[", "]"):
+                self.interleave(lambda: self.write(", "), self.traverse, type_params)
+
+    def visit_TypeVar(self, node):
+        self.write(node.name)
+        if node.bound:
+            self.write(": ")
+            self.traverse(node.bound)
+
+    def visit_TypeVarTuple(self, node):
+        self.write("*" + node.name)
+
+    def visit_ParamSpec(self, node):
+        self.write("**" + node.name)
+
+    def visit_TypeAlias(self, node):
+        self.fill("type ")
+        self.traverse(node.name)
+        self._type_params_helper(node.type_params)
+        self.write(" = ")
+        self.traverse(node.value)
+
     def visit_For(self, node):
         self._for_helper("for ", node)
 

tests/test_unparser.py

@@ -0,0 +1,37 @@
+import unittest
+
+import ast
+import gast
+import sys
+
+
+class UnparserTestCase(unittest.TestCase):
+
+    def __init__(self, *args, **kwargs):
+        unittest.TestCase.__init__(self, *args, **kwargs)
+        self.maxDiff = None
+
+    def assertUnparse(self, code):
+        normalized_code = ast.unparse(ast.parse(code))
+        tree = gast.parse(normalized_code)
+        compile(gast.gast_to_ast(tree), '<test>', 'exec')
+        unparsed = gast.unparse(tree)
+        self.assertEqual(normalized_code, unparsed)
+
+    def test_FunctionDef(self):
+        self.assertUnparse('def foo(x, y): return x, y')
+
+    def test_BinaryOp(self):
+        self.assertUnparse('1 + 3')
+
+    if sys.version_info >= (3, 12):
+
+        def test_TypeParameter(self):
+            self.assertUnparse('type x[T] = list[T]')
+
+
+if sys.version_info < (3, 9):
+    del UnparserTestCase
+
+if __name__ == '__main__':
+    unittest.main()