[core] Type represent_sensitive and hoist SensitiveStr import in test

esphome/yaml_util.py

@@ -1013,7 +1013,7 @@ class ESPHomeDumper(yaml.SafeDumper):
             return self.represent_secret(value)
         return self.represent_scalar(tag="tag:yaml.org,2002:str", value=str(value))
 
-    def represent_sensitive(self, value):
+    def represent_sensitive(self, value: SensitiveStr) -> yaml.ScalarNode:
         # ``!secret`` references win: keep the original representation so the
         # dumped YAML round-trips back to ``!secret name`` instead of leaking
         # the resolved value.

tests/unit_tests/test_config_validation.py

@@ -27,6 +27,7 @@ from esphome.const import (
     SCHEDULER_DONT_RUN,
 )
 from esphome.core import CORE, HexInt, Lambda
+from esphome.yaml_util import SensitiveStr
 
 
 def test_check_not_templatable__invalid():
@@ -146,8 +147,6 @@ def test_sensitive__custom_inner_delegates_validation() -> None:
 
 
 def test_sensitive__wraps_string_result_in_sensitive_str() -> None:
-    from esphome.yaml_util import SensitiveStr
-
     validator = config_validation.sensitive()
     result = validator("hunter2")
 
@@ -157,8 +156,6 @@ def test_sensitive__wraps_string_result_in_sensitive_str() -> None:
 
 
 def test_sensitive__does_not_double_tag_already_sensitive() -> None:
-    from esphome.yaml_util import SensitiveStr
-
     # If the inner validator already returns a SensitiveStr (e.g., nested
     # cv.sensitive wrappers), re-tagging is a no-op rather than a new
     # SensitiveStr around the same value.