Type Annotations: ext.scrub

- Resolves Issue #724
    - Related to PR #628

CHANGELOG.md

@@ -58,6 +58,7 @@ Refactoring:
     - `[ext.plugin]` [Issue #721](https://github.com/datafolklabs/cement/issues/721)
     - `[ext.print]` [Issue #722](https://github.com/datafolklabs/cement/issues/722)
     - `[ext.redis]` [Issue #723](https://github.com/datafolklabs/cement/issues/723)
+    - `[ext.scrub]` [Issue #724](https://github.com/datafolklabs/cement/issues/724)
     - `[utils.fs]` [Issue #688](https://github.com/datafolklabs/cement/issues/688)
     - `[utils.misc]` [Issue #689](https://github.com/datafolklabs/cement/issues/689)
     - `[utils.shell]` [Issue #690](https://github.com/datafolklabs/cement/issues/690)

cement/ext/ext_scrub.py

@@ -2,21 +2,26 @@
 Cement scrub extension module.
 """
 
+from __future__ import annotations
 import re
+from typing import TYPE_CHECKING
 from .. import Controller
 from ..utils.misc import minimal_logger
 
+if TYPE_CHECKING:
+    from ..core.foundation import App  # pragma: nocover
+
 LOG = minimal_logger(__name__)
 
 
-def scrub_output(app, text):
+def scrub_output(app: App, text: str) -> str:
     if app.pargs.scrub:
         text = app.scrub(text)
     return text
 
 
-def extend_scrub(app):
-    def scrub(text):
+def extend_scrub(app: App) -> None:
+    def scrub(text: str) -> str:
         if not hasattr(app._meta, 'scrub') or app._meta.scrub is None:
             return text  # pragma: nocover
         elif isinstance(text, str):
@@ -34,7 +39,7 @@ class ScrubController(Controller):
     Add embedded options to the base controller to support scrubbing output.
     """
 
-    class Meta:
+    class Meta(Controller.Meta):
         #: Controller label
         label = 'scrub'
 
@@ -50,7 +55,9 @@ class ScrubController(Controller):
         #: Command line argument options help
         argument_help = 'obfuscate sensitive data from rendered output'
 
-    def _pre_argument_parsing(self):
+    _meta: Meta  # type: ignore
+
+    def _pre_argument_parsing(self) -> None:
         if self._meta.argument_options is not None:
             assert isinstance(self._meta.argument_options, list), \
                 "ScrubController.Meta.argument_options must be a list"
@@ -60,7 +67,7 @@ class ScrubController(Controller):
                                        dest='scrub')
 
 
-def load(app):
+def load(app: App) -> None:
     app.handler.register(ScrubController)
     app.hook.register('post_render', scrub_output)
     app.hook.register('pre_argument_parsing', extend_scrub)