avoid importing gradio in tests because it spams warnings

test/conftest.py

 import os
 
 import pytest
-from PIL import Image
-from gradio.processing_utils import encode_pil_to_base64
+import base64
+
 
 test_files_path = os.path.dirname(__file__) + "/test_files"
 
 
+def file_to_base64(filename):
+    with open(filename, "rb") as file:
+        data = file.read()
+
+    base64_str = str(base64.b64encode(data), "utf-8")
+    return "data:image/png;base64," + base64_str
+
+
 @pytest.fixture(scope="session")  # session so we don't read this over and over
 def img2img_basic_image_base64() -> str:
-    return encode_pil_to_base64(Image.open(os.path.join(test_files_path, "img2img_basic.png")))
+    return file_to_base64(os.path.join(test_files_path, "img2img_basic.png"))
 
 
 @pytest.fixture(scope="session")  # session so we don't read this over and over
 def mask_basic_image_base64() -> str:
-    return encode_pil_to_base64(Image.open(os.path.join(test_files_path, "mask_basic.png")))
+    return file_to_base64(os.path.join(test_files_path, "mask_basic.png"))