feat: Add NO_IMAGE enum value to FinishReason

PiperOrigin-RevId: 814377707

Author: matthew29tang

google/genai/tests/models/test_generate_content_image_generation.py

@@ -50,6 +50,19 @@
             ),
         ),
     ),
+    pytest_helper.TestTableItem(
+        name='test_image_generation_no_image',
+        parameters=types._GenerateContentParameters(
+            model='gemini-2.5-flash-image',
+            contents=t.t_contents('What is your name?'),
+            config=types.GenerateContentConfig(
+                response_modalities=['IMAGE'],
+                image_config=types.ImageConfig(
+                    aspect_ratio='16:9',
+                )
+            ),
+        ),
+    ),
     pytest_helper.TestTableItem(
         name='test_image_generation_config_validation_none',
         parameters=types._GenerateContentParameters(

google/genai/types.py

@@ -287,6 +287,8 @@ class FinishReason(_common.CaseInSensitiveEnum):
   """The tool call generated by the model is invalid."""
   IMAGE_PROHIBITED_CONTENT = 'IMAGE_PROHIBITED_CONTENT'
   """Image generation stopped because the generated images have prohibited content."""
+  NO_IMAGE = 'NO_IMAGE'
+  """The model was expected to generate an image, but none was generated."""
 
 
 class HarmProbability(_common.CaseInSensitiveEnum):