chore: import upstream snapshot with attribution

tests/utils/test_document_validator.py

@@ -0,0 +1,54 @@
+from __future__ import annotations
+
+from deeptutor.services.rag.file_routing import FileTypeRouter
+from deeptutor.utils.document_validator import DocumentValidator
+
+
+def test_validate_upload_safety_preserves_unicode_and_lowercases_extension() -> None:
+    safe_name = DocumentValidator.validate_upload_safety(
+        "中文资料/数学 讲义#1(最终版).PDF",
+        1024,
+        allowed_extensions=FileTypeRouter.get_supported_extensions(),
+    )
+
+    assert safe_name == "数学 讲义#1(最终版).pdf"
+
+
+def test_validate_upload_safety_strips_windows_path_components() -> None:
+    safe_name = DocumentValidator.validate_upload_safety(
+        r"C:\Users\frank\资料\报告.MD",
+        128,
+        allowed_extensions=FileTypeRouter.get_supported_extensions(),
+    )
+
+    assert safe_name == "报告.md"
+
+
+def test_validate_upload_safety_accepts_chat_office_formats_for_kb_policy() -> None:
+    safe_name = DocumentValidator.validate_upload_safety(
+        "Lecture Notes.DOCX",
+        1024,
+        allowed_extensions=FileTypeRouter.get_supported_extensions(),
+    )
+
+    assert safe_name == "Lecture Notes.docx"
+
+
+def test_validate_upload_safety_custom_policy_allows_supported_code_mimes() -> None:
+    safe_name = DocumentValidator.validate_upload_safety(
+        "solver.PY",
+        1024,
+        allowed_extensions=FileTypeRouter.get_supported_extensions(),
+    )
+
+    assert safe_name == "solver.py"
+
+
+def test_validate_upload_safety_custom_policy_allows_images() -> None:
+    safe_name = DocumentValidator.validate_upload_safety(
+        "diagram.PNG",
+        1024,
+        allowed_extensions=FileTypeRouter.get_supported_extensions(),
+    )
+
+    assert safe_name == "diagram.png"