Make py__iter__ work as well for Interpreter

jedi/inference/value/instance.py

@@ -150,6 +150,16 @@ class AbstractInstanceValue(Value):
         args = ValuesArguments([index_value_set])
         return ValueSet.from_sets(name.infer().execute(args) for name in names)
 
+    def py__iter__(self, contextualized_node=None):
+        iter_slot_names = self.get_function_slot_names('__iter__')
+        if not iter_slot_names:
+            return super().py__iter__(contextualized_node)
+
+        def iterate():
+            for generator in self.execute_function_slots(iter_slot_names):
+                yield from generator.py__next__(contextualized_node)
+        return iterate()
+
     def __repr__(self):
         return "<%s of %s>" % (self.__class__.__name__, self.class_value)
 
@@ -254,16 +264,6 @@ class _BaseTreeInstance(AbstractInstanceValue):
                  or self.get_function_slot_names('__getattribute__'))
         return self.execute_function_slots(names, name)
 
-    def py__iter__(self, contextualized_node=None):
-        iter_slot_names = self.get_function_slot_names('__iter__')
-        if not iter_slot_names:
-            return super().py__iter__(contextualized_node)
-
-        def iterate():
-            for generator in self.execute_function_slots(iter_slot_names):
-                yield from generator.py__next__(contextualized_node)
-        return iterate()
-
     def py__next__(self, contextualized_node=None):
         name = u'__next__'
         next_slot_names = self.get_function_slot_names(name)

test/test_api/test_interpreter.py

@@ -600,16 +600,31 @@ def test_dict_getitem(code, types):
 
 
 @pytest.mark.parametrize('class_is_findable', [False, True])
-def test__getitem__(class_is_findable):
+@pytest.mark.parametrize(
-    class GetitemCls:
+    'code, expected', [
+        ('DunderCls()[0]', 'int'),
+        ('next(DunderCls())', 'float'),
+        ('for x in DunderCls(): x', 'str'),
+    ]
+)
+def test_dunders(class_is_findable, code, expected):
+    from typing import Iterator
+
+    class DunderCls:
         def __getitem__(self, key) -> int:
             pass
 
-    if not class_is_findable:
+        def __iter__(self, key) -> Iterator[str]:
-        GetitemCls.__name__ = 'asdf'
+            pass
 
-    n, = jedi.Interpreter('GetitemCls()[0]', [locals()]).infer()
+        def __next__(self, key) -> float:
-    assert n.name == 'int'
+            pass
+
+    if not class_is_findable:
+        DunderCls.__name__ = 'asdf'
+
+    n, = jedi.Interpreter(code, [locals()]).infer()
+    assert n.name == expected
 
 
 def foo():