Update mm test: create dummy image in case file corrput (#2258)

Author: BeibinLi

test/agentchat/contrib/capabilities/test_vision_capability.py

@@ -1,10 +1,13 @@
+import os
 from unittest.mock import MagicMock, patch
 
 import pytest
 
 from autogen.agentchat.conversable_agent import ConversableAgent
 
 try:
+    from PIL import Image
+
     from autogen.agentchat.contrib.capabilities.vision_capability import VisionCapability
 except ImportError:
     skip_test = True
@@ -21,6 +24,15 @@ def lmm_config():
     }
 
 
+def png_filename() -> str:
+    filename = "tmp/test_image.png"
+    if not os.path.exists(filename):
+        # Setup: Create a PNG file
+        image = Image.new("RGB", (100, 100), color="blue")
+        image.save(filename)
+    return filename  # This is what the test will use
+
+
 @pytest.fixture
 def vision_capability(lmm_config):
     return VisionCapability(lmm_config, custom_caption_func=None)
@@ -72,9 +84,9 @@ def test_process_last_received_message_text(mock_lmm_client, vision_capability):
 def test_process_last_received_message_with_image(
     mock_get_caption, mock_convert_base64, mock_get_image_data, vision_capability
 ):
-    content = [{"type": "image_url", "image_url": {"url": "notebook/viz_gc.png"}}]
+    content = [{"type": "image_url", "image_url": {"url": (png_filename())}}]
     expected_caption = (
-        "<img notebook/viz_gc.png> in case you can not see, the caption of this image is: A sample image caption.\n"
+        f"<img {png_filename()}> in case you can not see, the caption of this image is: A sample image caption.\n"
     )
     processed_content = vision_capability.process_last_received_message(content)
     assert processed_content == expected_caption
@@ -101,15 +113,15 @@ def caption_func(image_url: str, image_data=None, lmm_client=None) -> str:
 class TestCustomCaptionFunc:
     def test_custom_caption_func_with_valid_url(self, custom_caption_func):
         """Test custom caption function with a valid image URL."""
-        image_url = "notebook/viz_gc.png"
+        image_url = png_filename()
         expected_caption = f"An image description. The image is from {image_url}."
         assert custom_caption_func(image_url) == expected_caption, "Caption does not match expected output."
 
     def test_process_last_received_message_with_custom_func(self, lmm_config, custom_caption_func):
         """Test processing a message containing an image URL with a custom caption function."""
         vision_capability = VisionCapability(lmm_config, custom_caption_func=custom_caption_func)
 
-        image_url = "notebook/viz_gc.png"
+        image_url = png_filename()
         content = [{"type": "image_url", "image_url": {"url": image_url}}]
         expected_output = f" An image description. The image is from {image_url}."
         processed_content = vision_capability.process_last_received_message(content)