fix: file path handling for cross-os compatibility (#5342)

* test: add more unit tests

* fix: correct file path splitting to handle OS differences

* [autofix.ci] apply automated fixes

* fix: ruff error

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

src/backend/tests/unit/schema/test_image.py

@@ -0,0 +1,84 @@
+import tempfile
+
+import aiofiles
+import pytest
+from langflow.schema.image import (
+    get_file_paths,
+    get_files,
+    is_image_file,
+)
+from PIL import Image as PILImage
+
+
+@pytest.fixture
+def file_image():
+    image = PILImage.new("RGB", (100, 100), (255, 0, 0))
+    with tempfile.NamedTemporaryFile(suffix=".png", delete=True) as temp_file:
+        image.save(temp_file.name)
+        yield temp_file.name
+
+
+@pytest.fixture
+def file_txt():
+    content = """\
+line1: This is an example text file.
+line2: It can be used for testing.
+line3: End of file.
+"""
+    with tempfile.NamedTemporaryFile(suffix=".txt", delete=False) as temp_file:
+        temp_file.write(content.encode())
+        temp_file.flush()
+        yield temp_file.name
+
+
+def test_is_image_file(file_image):
+    assert is_image_file(file_image) is True
+
+
+def test_is_image_file__not_image(file_txt):
+    assert is_image_file(file_txt) is False
+
+
+def test_get_file_paths(file_image, file_txt):
+    files = [file_image, file_txt]
+
+    result = get_file_paths(files)
+
+    assert len(result) == 2
+    assert result[0].endswith(".png")
+    assert result[1].endswith(".txt")
+
+
+def test_get_file_paths__empty():
+    result = get_file_paths([])
+
+    assert len(result) == 0
+
+
+@pytest.mark.asyncio
+async def test_get_files(file_image, file_txt, caplog):  # noqa: ARG001
+    file_paths = [file_image, file_txt]
+
+    result = await get_files(file_paths)
+
+    for index, file in enumerate(result):
+        async with aiofiles.open(file_paths[index], "rb") as f:
+            assert file == await f.read()
+
+
+@pytest.mark.asyncio
+async def test_get_files__convert_to_base64(file_image, file_txt, caplog):  # noqa: ARG001
+    file_paths = [file_image, file_txt]
+
+    result = await get_files(file_paths, convert_to_base64=True)
+
+    for index, file in enumerate(result):
+        async with aiofiles.open(file_paths[index], "rb") as f:
+            assert file != await f.read()
+
+
+@pytest.mark.asyncio
+async def test_get_files__empty():
+    result = await get_files([])
+
+    assert len(result) == 0