add tests for MethodDispatcherTransform

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, 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, args, unbound):
+                calls['bytes'] += 1
+                return node
+            def _handle_simple_method_object___mul__(self, node, args, unbound):
+                calls['object'] += 1
+                return node
+
+        tree = self._build_tree()
+        Test(None)(tree)
+        self.assertEqual(1, calls['bytes'])
+        self.assertEqual(0, calls['object'])