Add unit test for safetensors embedded image previews

tests-unit/app_test/model_manager_test.py

@@ -0,0 +1,62 @@
+import pytest
+import base64
+import json
+import struct
+from io import BytesIO
+from PIL import Image
+from aiohttp import web
+from unittest.mock import patch
+from app.model_manager import ModelFileManager
+
+pytestmark = (
+    pytest.mark.asyncio
+)  # This applies the asyncio mark to all test functions in the module
+
+@pytest.fixture
+def model_manager():
+    return ModelFileManager()
+
+@pytest.fixture
+def app(model_manager):
+    app = web.Application()
+    routes = web.RouteTableDef()
+    model_manager.add_routes(routes)
+    app.add_routes(routes)
+    return app
+
+async def test_get_model_preview_safetensors(aiohttp_client, app, tmp_path):
+    img = Image.new('RGB', (100, 100), 'white')
+    img_byte_arr = BytesIO()
+    img.save(img_byte_arr, format='PNG')
+    img_byte_arr.seek(0)
+    img_b64 = base64.b64encode(img_byte_arr.getvalue()).decode('utf-8')
+
+    safetensors_file = tmp_path / "test_model.safetensors"
+    header_bytes = json.dumps({
+        "__metadata__": {
+            "ssmd_cover_images": json.dumps([img_b64])
+        }
+    }).encode('utf-8')
+    length_bytes = struct.pack('<Q', len(header_bytes))
+    with open(safetensors_file, 'wb') as f:
+        f.write(length_bytes)
+        f.write(header_bytes)
+
+    with patch('folder_paths.folder_names_and_paths', {
+        'test_folder': ([str(tmp_path)], None)
+    }):
+        client = await aiohttp_client(app)
+        response = await client.get('/experiment/models/preview/test_folder/0/test_model.safetensors')
+
+        # Verify response
+        assert response.status == 200
+        assert response.content_type == 'image/webp'
+
+        # Verify the response contains valid image data
+        img_bytes = BytesIO(await response.read())
+        img = Image.open(img_bytes)
+        assert img.format
+        assert img.format.lower() == 'webp'
+
+        # Clean up
+        img.close()