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# Copyright (c) Meta Platforms, Inc. and affiliates.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.
from typing import List
import libcst as cst
from libcst import CSTTransformer, CSTVisitor, parse_module
from libcst.testing.utils import UnitTest
class VisitorTest(UnitTest):
def test_visitor(self) -> None:
class SomeVisitor(CSTVisitor):
def __init__(self) -> None:
self.visit_order: List[str] = []
def visit_If(self, node: cst.If) -> None:
self.visit_order.append("visit_If")
def leave_If(self, original_node: cst.If) -> None:
self.visit_order.append("leave_If")
def visit_If_test(self, node: cst.If) -> None:
self.visit_order.append("visit_If_test")
def leave_If_test(self, node: cst.If) -> None:
self.visit_order.append("leave_If_test")
def visit_Name(self, node: cst.Name) -> None:
self.visit_order.append("visit_Name")
def leave_Name(self, original_node: cst.Name) -> None:
self.visit_order.append("leave_Name")
# Create and visit a simple module.
module = parse_module("if True:\n pass")
visitor = SomeVisitor()
module.visit(visitor)
# Check that visits worked.
self.assertEqual(
visitor.visit_order,
[
"visit_If",
"visit_If_test",
"visit_Name",
"leave_Name",
"leave_If_test",
"leave_If",
],
)
def test_transformer(self) -> None:
class SomeTransformer(CSTTransformer):
def __init__(self) -> None:
self.visit_order: List[str] = []
def visit_If(self, node: cst.If) -> None:
self.visit_order.append("visit_If")
def leave_If(self, original_node: cst.If, updated_node: cst.If) -> cst.If:
self.visit_order.append("leave_If")
return updated_node
def visit_If_test(self, node: cst.If) -> None:
self.visit_order.append("visit_If_test")
def leave_If_test(self, node: cst.If) -> None:
self.visit_order.append("leave_If_test")
def visit_Name(self, node: cst.Name) -> None:
self.visit_order.append("visit_Name")
def leave_Name(
self, original_node: cst.Name, updated_node: cst.Name
) -> cst.Name:
self.visit_order.append("leave_Name")
return updated_node
# Create and visit a simple module.
module = parse_module("if True:\n pass")
transformer = SomeTransformer()
module.visit(transformer)
# Check that visits worked.
self.assertEqual(
transformer.visit_order,
[
"visit_If",
"visit_If_test",
"visit_Name",
"leave_Name",
"leave_If_test",
"leave_If",
],
)
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