feat: replace 'assert' added to satisfy type checking

Based on feedback from @T4rk1n, removed assertions added to satisfy
type checker and used other mechanisms instead.

Author: gvwilson

dash/_pages.py

@@ -8,6 +8,7 @@
 from pathlib import Path
 from os.path import isfile, join
 from urllib.parse import parse_qs, unquote
+from typing import cast
 
 import flask
 
@@ -86,8 +87,7 @@ def _infer_path(module_name, template):
 
 
 def _module_name_is_package(module_name):
-    file_path = sys.modules[module_name].__file__
-    assert file_path is not None  # to make type checker happy
+    file_path = cast(str, sys.modules[module_name].__file__)  # to satisfy type checking
     return module_name in sys.modules and Path(file_path).name == "__init__.py"
 
 
@@ -441,11 +441,8 @@ def _import_layouts_from_pages(pages_folder):
 
             module_name = _infer_module_name(page_path)
             spec = importlib.util.spec_from_file_location(module_name, page_path)
-            assert (
-                spec is not None and spec.loader is not None
-            )  # to satisfy type checking
-            page_module = importlib.util.module_from_spec(spec)
-            spec.loader.exec_module(page_module)
+            page_module = importlib.util.module_from_spec(spec)  # type: ignore[reportArgumentType]
+            spec.loader.exec_module(page_module)  # type: ignore[reportOptionalMemberAccess]
             sys.modules[module_name] = page_module
 
             if (

dash/background_callback/managers/celery_manager.py

@@ -157,8 +157,7 @@ def _set_props(_id, props):
         ctx = copy_context()
 
         def run():
-            assert isinstance(context, dict)  # to help type checking
-            c = AttributeDict(**context)
+            c = AttributeDict(**context)  # type: ignore[reportCallIssue]
             c.ignore_register_page = False
             c.updated_props = ProxySetProps(_set_props)
             context_value.set(c)

dash/dash.py

@@ -18,7 +18,7 @@
 import base64
 import traceback
 from urllib.parse import urlparse
-from typing import Any, Callable, Dict, Optional, Union, Sequence
+from typing import Any, Callable, Dict, Optional, Union, Sequence, cast
 
 import flask
 
@@ -452,7 +452,7 @@ def __init__(  # pylint: disable=too-many-statements
             url_base_pathname, routes_pathname_prefix, requests_pathname_prefix
         )
 
-        assert isinstance(name, str)  # to satisfy type checking
+        name = cast(str, name)  # to satisfy type checking
         self.config = AttributeDict(
             name=name,
             assets_folder=os.path.join(
@@ -767,8 +767,7 @@ def layout(self, value):
 
     def _layout_value(self):
         if self._layout_is_function:
-            assert callable(self._layout)
-            layout = self._layout()
+            layout = self._layout()  # type: ignore[reportOptionalCall]
         else:
             layout = self._layout
 

dash/development/base_component.py

@@ -301,12 +301,10 @@ def _get_set_or_delete(self, id, operation, new_item=None):
                     if operation == "get":
                         return item
                     if operation == "set":
-                        assert self.children is not None  # to satisfy type checking
-                        self.children[i] = new_item
+                        self.children[i] = new_item  # type: ignore[reportOptionalSubscript]
                         return
                     if operation == "delete":
-                        assert self.children is not None  # to satisfy type checking
-                        del self.children[i]
+                        del self.children[i]  # type: ignore[reportOptionalSubscript]
                         return
 
                 # Otherwise, recursively dig into that item's subtree

dash/testing/application_runners.py

@@ -9,6 +9,7 @@
 import logging
 import inspect
 import ctypes
+from typing import cast
 
 import runpy
 import requests
@@ -353,15 +354,16 @@ def start(self, app, start_timeout=2, cwd=None):  # type: ignore[reportIncompati
             # app is a string chunk, we make a temporary folder to store app.R
             # and its relevant assets
             tmp_dir = "/tmp" if not self.is_windows else os.getenv("TEMP")
-            assert isinstance(tmp_dir, str)
+            tmp_dir = cast(str, tmp_dir)  # to satisfy type checking
             hex_id = uuid.uuid4().hex
-            self._tmp_app_path = os.path.join(tmp_dir, hex_id)
-            assert isinstance(self.tmp_app_path, str)  # to satisfy type checking
+            self._tmp_app_path = cast(
+                str, os.path.join(tmp_dir, hex_id)
+            )  # to satisfy type checking
             try:
-                os.mkdir(self.tmp_app_path)
+                os.mkdir(self.tmp_app_path)  # type: ignore[reportArgumentType]
             except OSError:
                 logger.exception("cannot make temporary folder %s", self.tmp_app_path)
-            path = os.path.join(self.tmp_app_path, "app.R")
+            path = os.path.join(self.tmp_app_path, "app.R")  # type: ignore[reportCallIssue]
 
             logger.info("RRunner start => app is R code chunk")
             logger.info("make a temporary R file for execution => %s", path)
@@ -392,7 +394,7 @@ def start(self, app, start_timeout=2, cwd=None):  # type: ignore[reportIncompati
                 ]
 
                 for asset in assets:
-                    target = os.path.join(self.tmp_app_path, os.path.basename(asset))
+                    target = os.path.join(self.tmp_app_path, os.path.basename(asset))  # type: ignore[reportCallIssue]
                     if os.path.exists(target):
                         logger.debug("delete existing target %s", target)
                         shutil.rmtree(target)

dash/testing/browser.py

@@ -3,6 +3,7 @@
 import sys
 import time
 import logging
+from typing import cast
 import warnings
 import percy
 import requests
@@ -119,7 +120,7 @@ def visit_and_snapshot(
         try:
             if path != resource_path:
                 logger.warning("we stripped the left '/' in resource_path")
-            assert isinstance(self.server_url, str)  # to satisfy type checking
+            self.server_url = cast(str, self.server_url)  # to satisfy type checking
             self.driver.get(f"{self.server_url.rstrip('/')}/{path}")
 
             # wait for the hook_id to present and all callbacks get fired
@@ -228,7 +229,7 @@ def take_snapshot(self, name):
         running selenium session id
         """
         target = "/tmp/dash_artifacts" if not self._is_windows() else os.getenv("TEMP")
-        assert isinstance(target, str)  # to satisfy type checking
+        target = cast(str, target)  # to satisfy type checking
         if not os.path.exists(target):
             try:
                 os.mkdir(target)
@@ -533,7 +534,7 @@ def _get_firefox(self):
             "browser.helperApps.neverAsk.saveToDisk",
             "application/octet-stream",  # this MIME is generic for binary
         )
-        assert isinstance(self._remote_url, str)  # to satisfy type checking
+        self._remote_url = cast(str, self._remote_url)  # to satisfy type checking
         return (
             webdriver.Remote(
                 command_executor=self._remote_url,