runtime/Lib/site-packages/Cython/Compiler/Tests/TestVisitor.py

from Cython.Compiler.ModuleNode import ModuleNode
from Cython.Compiler.Symtab import ModuleScope
from Cython.TestUtils import TransformTest
from Cython.Compiler.Visitor import MethodDispatcherTransform
from Cython.Compiler.ParseTreeTransforms import (
    NormalizeTree, AnalyseDeclarationsTransform,
    AnalyseExpressionsTransform, InterpretCompilerDirectives)


class TestMethodDispatcherTransform(TransformTest):
    _tree = None

    def _build_tree(self):
        if self._tree is None:
            context = None

            def fake_module(node):
                scope = ModuleScope('test', None, None)
                return ModuleNode(node.pos, doc=None, body=node,
                                  scope=scope, full_module_name='test',
                                  directive_comments={})
            pipeline = [
                fake_module,
                NormalizeTree(context),
                InterpretCompilerDirectives(context, {}),
                AnalyseDeclarationsTransform(context),
                AnalyseExpressionsTransform(context),
            ]
            self._tree = self.run_pipeline(pipeline, u"""
                cdef bytes s = b'asdfg'
                cdef dict d = {1:2}
                x = s * 3
                d.get('test')
            """)
        return self._tree

    def test_builtin_method(self):
        calls = [0]
        class Test(MethodDispatcherTransform):
            def _handle_simple_method_dict_get(self, node, func, args, unbound):
                calls[0] += 1
                return node

        tree = self._build_tree()
        Test(None)(tree)
        self.assertEqual(1, calls[0])

    def test_binop_method(self):
        calls = {'bytes': 0, 'object': 0}
        class Test(MethodDispatcherTransform):
            def _handle_simple_method_bytes___mul__(self, node, func, args, unbound):
                calls['bytes'] += 1
                return node
            def _handle_simple_method_object___mul__(self, node, func, args, unbound):
                calls['object'] += 1
                return node

        tree = self._build_tree()
        Test(None)(tree)
        self.assertEqual(1, calls['bytes'])
        self.assertEqual(0, calls['object'])