feat: support image inputs in assistant tests

backend/services/test_assets.py

@@ -0,0 +1,44 @@
+"""Persistent image fixtures used by repeatable assistant test cases."""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+from services.image_processing import normalize_image
+from services.object_storage import delete_object, get_object, put_object
+
+
+TEST_ASSET_PREFIX = "test-assets/"
+
+
+@dataclass(frozen=True)
+class StoredTestImage:
+    storage_key: str
+    width: int
+    height: int
+    size_bytes: int
+    mime_type: str = "image/jpeg"
+
+
+def store_test_image(asset_id: str, data: bytes) -> StoredTestImage:
+    normalized, width, height = normalize_image(data)
+    key = f"{TEST_ASSET_PREFIX}{asset_id}.jpg"
+    put_object(key, normalized, "image/jpeg")
+    return StoredTestImage(
+        storage_key=key,
+        width=width,
+        height=height,
+        size_bytes=len(normalized),
+    )
+
+
+def read_test_image(storage_key: str) -> bytes:
+    if not storage_key.startswith(TEST_ASSET_PREFIX):
+        raise ValueError("测试图片存储位置无效")
+    return get_object(storage_key)
+
+
+def delete_test_image(storage_key: str) -> None:
+    if not storage_key.startswith(TEST_ASSET_PREFIX):
+        raise ValueError("测试图片存储位置无效")
+    delete_object(storage_key)