Addon Manager: refactor process_string_to_datetime (#18492)

* Addon Manager: Refactor utilities tests to remove filesystem use

* Addon Manager: Move process_date_string_to_python_datetime to utilities

Also add unit tests and modify the exception type

* Addon Manager: Add tests for other date separators

* Addon Manager: Refactor to reduce duplication

* Addon Manager: add explanation of why the function exists

* Addon Manager: use exception chaining

* Addon Manager: Remove unused test files

src/Mod/AddonManager/addonmanager_utilities.py

@@ -24,8 +24,12 @@
 
 """ Utilities to work across different platforms, providers and python versions """
 
+from datetime import datetime
+from typing import Optional, Any
+import ctypes
 import os
 import platform
+import re
 import shutil
 import stat
 import subprocess
@@ -443,6 +447,37 @@ def run_interruptable_subprocess(args, timeout_secs: int = 10) -> subprocess.Com
     return subprocess.CompletedProcess(args, return_code, stdout, stderr)
 
 
+def process_date_string_to_python_datetime(date_string: str) -> datetime:
+    """For modern macros the expected date format is ISO 8601, YYYY-MM-DD. For older macros this standard was not always
+    used, and various orderings and separators were used. This function tries to match the majority of those older
+    macros. Commonly-used separators are periods, slashes, and dashes."""
+
+    def raise_error(bad_string: str, root_cause: Exception = None):
+        raise ValueError(
+            f"Unrecognized date string '{bad_string}' (expected YYYY-MM-DD)"
+        ) from root_cause
+
+    split_result = re.split(r"[ ./-]+", date_string.strip())
+    if len(split_result) != 3:
+        raise_error(date_string)
+
+    try:
+        split_result = [int(x) for x in split_result]
+        # The earliest possible year an addon can be created or edited is 2001:
+        if split_result[0] > 2000:
+            return datetime(split_result[0], split_result[1], split_result[2])
+        elif split_result[2] > 2000:
+            # Generally speaking it's not possible to distinguish between DD-MM and MM-DD, so try the first, and
+            # only if that fails try the second
+            if split_result[1] <= 12:
+                return datetime(split_result[2], split_result[1], split_result[0])
+            return datetime(split_result[2], split_result[0], split_result[1])
+        else:
+            raise ValueError(f"Invalid year in date string '{date_string}'")
+    except ValueError as exception:
+        raise_error(date_string, exception)
+
+
 def get_main_am_window():
     windows = QtWidgets.QApplication.topLevelWidgets()
     for widget in windows: