Fix pages modules is package

.github/workflows/testing.yml

@@ -2,6 +2,10 @@ name: Dash Testing
 
 on:
   push:
+    branches:
+      - dev
+      - master
+  pull_request:
   workflow_dispatch:
 
 jobs:

CHANGELOG.md

@@ -8,6 +8,7 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 ## Fixed
 - [#3279](https://github.com/plotly/dash/pull/3279) Fix an issue where persisted values were incorrectly pruned when updated via callback. Now, callback returned values are correctly stored in the persistence storage. Fix [#2678](https://github.com/plotly/dash/issues/2678)
 - [#3298](https://github.com/plotly/dash/pull/3298) Fix dev_only resources filtering.
+- [#3315](https://github.com/plotly/dash/pull/3315) Fix pages module is package check.
 
 ## Added
 - [#3294](https://github.com/plotly/dash/pull/3294) Added the ability to pass `allow_optional` to Input and State to allow callbacks to work even if these components are not in the dash layout.

dash/_pages.py

@@ -86,12 +86,10 @@ def _infer_path(module_name, template):
 
 
 def _module_name_is_package(module_name):
-    file_path = sys.modules[module_name].__file__
-    return (
-        file_path
-        and module_name in sys.modules
-        and Path(file_path).name == "__init__.py"
-    )
+    if module_name not in sys.modules:
+        return False
+    file = sys.modules[module_name].__file__
+    return file and file.endswith("__init__.py")
 
 
 def _path_to_module_name(path):