fix tests and add new versions

Author: cloudQuant

.github/workflows/test.yml

@@ -55,7 +55,9 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          # Ubuntu - test all stable Python versions (3.9 to 3.13)
+          # Ubuntu - test all Python versions (3.8 to 3.13)
+          - os: ubuntu-latest
+            python-version: '3.8'
           - os: ubuntu-latest
             python-version: '3.9'
           - os: ubuntu-latest
@@ -67,19 +69,31 @@ jobs:
           - os: ubuntu-latest
             python-version: '3.13'
 
-          # macOS - test representative Python versions
+          # macOS - test all Python versions (3.8 to 3.13)
+          - os: macos-latest
+            python-version: '3.8'
           - os: macos-latest
             python-version: '3.9'
+          - os: macos-latest
+            python-version: '3.10'
           - os: macos-latest
             python-version: '3.11'
+          - os: macos-latest
+            python-version: '3.12'
           - os: macos-latest
             python-version: '3.13'
 
-          # Windows - test representative Python versions
+          # Windows - test all Python versions (3.8 to 3.13)
+          - os: windows-latest
+            python-version: '3.8'
           - os: windows-latest
             python-version: '3.9'
+          - os: windows-latest
+            python-version: '3.10'
           - os: windows-latest
             python-version: '3.11'
+          - os: windows-latest
+            python-version: '3.12'
           - os: windows-latest
             python-version: '3.13'
 

backtrader/mixins/singleton.py

@@ -20,7 +20,7 @@
 """
 import threading
 import weakref
-from typing import Any
+from typing import Any, Dict, Optional
 
 
 class SingletonMixin:
@@ -41,7 +41,7 @@ class SingletonMixin:
 
     # Class-level storage for singleton instances
     # Using WeakValueDictionary for automatic cleanup
-    _instances: dict[type, Any] = weakref.WeakValueDictionary()
+    _instances: Dict[type, Any] = weakref.WeakValueDictionary()
     _lock = threading.Lock()
 
     def __new__(cls, *args, **kwargs):
@@ -86,7 +86,7 @@ def _reset_instance(cls):
                 del cls._instances[cls]
 
     @classmethod
-    def _get_instance(cls) -> Any | None:
+    def _get_instance(cls) -> Optional[Any]:
         """Get the current singleton instance if it exists.
 
         Returns:

setup.py

@@ -16,7 +16,7 @@
     long_description_content_type="text/markdown",  # Long description content type
     url="https://gitee.com/yunjinqi/backtrader.git",  # Project URL
     install_requires=[
-        # Use flexible numpy version for Python 3.9-3.13 compatibility
+        # Use flexible numpy version for Python 3.8-3.13 compatibility
         "numpy>=1.20.0,<3.0.0",
         "pytz>=2021.1",
         "pandas>=1.3.0",
@@ -43,6 +43,7 @@
     },  # List of project dependencies
     classifiers=[
         "Programming Language :: Python :: 3",
+        "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
         "Programming Language :: Python :: 3.10",
         "Programming Language :: Python :: 3.11",