Solve import cycles in expandtype and testtypes.py (#15580)

Author: sobolevn

mypy/expandtype.py

@@ -5,7 +5,6 @@
 
 from mypy.nodes import ARG_POS, ARG_STAR, ArgKind, Var
 from mypy.state import state
-from mypy.type_visitor import TypeTranslator
 from mypy.types import (
     ANY_STRATEGY,
     AnyType,
@@ -44,6 +43,9 @@
 )
 from mypy.typevartuples import find_unpack_in_list, split_with_instance
 
+# Solving the import cycle:
+import mypy.type_visitor  # ruff: isort: skip
+
 # WARNING: these functions should never (directly or indirectly) depend on
 # is_subtype(), meet_types(), join_types() etc.
 # TODO: add a static dependency test for this.
@@ -167,7 +169,7 @@ def freshen_all_functions_type_vars(t: T) -> T:
         return result
 
 
-class FreshenCallableVisitor(TypeTranslator):
+class FreshenCallableVisitor(mypy.type_visitor.TypeTranslator):
     def visit_callable_type(self, t: CallableType) -> Type:
         result = super().visit_callable_type(t)
         assert isinstance(result, ProperType) and isinstance(result, CallableType)

mypy/test/testtypes.py

@@ -5,9 +5,7 @@
 import re
 from unittest import TestCase, skipUnless
 
-import mypy.expandtype
 from mypy.erasetype import erase_type, remove_instance_last_known_values
-from mypy.expandtype import expand_type
 from mypy.indirection import TypeIndirectionVisitor
 from mypy.join import join_simple, join_types
 from mypy.meet import meet_types, narrow_declared_type
@@ -53,6 +51,9 @@
     has_recursive_types,
 )
 
+# Solving the import cycle:
+import mypy.expandtype  # ruff: isort: skip
+
 
 class TypesSuite(Suite):
     def setUp(self) -> None:
@@ -268,7 +269,7 @@ def assert_expand(
         for id, t in map_items:
             lower_bounds[id] = t
 
-        exp = expand_type(orig, lower_bounds)
+        exp = mypy.expandtype.expand_type(orig, lower_bounds)
         # Remove erased tags (asterisks).
         assert_equal(str(exp).replace("*", ""), str(result))