test: add unit test for fallback path non_default_params forwarding

This test ensures that non-default parameters are correctly forwarded to the fallback image_edit_handler, addressing a regression issue.

tests/image_gen_tests/test_image_edit.py

@@ -0,0 +1,69 @@
+"""
+Tests for the image_edit() function in litellm/images/main.py
+"""
+
+import io
+import os
+import sys
+from unittest.mock import MagicMock, patch
+
+sys.path.insert(0, os.path.abspath("../.."))
+
+import litellm
+
+
+def test_image_edit_fallback_forwards_non_default_params():
+    """
+    Regression test: non_default_params must reach the fallback image_edit_handler
+    path (i.e. providers other than bedrock / stability / black_forest_labs).
+
+    Before gh-30814 the fallback path was missing::
+
+        image_edit_request_params.update(non_default_params)
+
+    so provider-specific kwargs such as ``image_config`` were silently dropped
+    before the call to base_llm_http_handler.image_edit_handler.
+    """
+    captured = {}
+
+    def _capture_handler(**kwargs):
+        captured.update(kwargs)
+        return litellm.ImageResponse(data=[])
+
+    mock_image = io.BytesIO(b"\x89PNGfake")
+    mock_image.name = "test.png"
+
+    mock_provider_config = MagicMock()
+    mock_utils = MagicMock()
+    mock_utils.get_requested_image_edit_optional_param.return_value = MagicMock()
+    mock_utils.get_optional_params_image_edit.return_value = {}
+
+    with (
+        patch(
+            "litellm.images.main.base_llm_http_handler.image_edit_handler",
+            side_effect=_capture_handler,
+        ),
+        patch(
+            "litellm.utils.ProviderConfigManager.get_provider_image_edit_config",
+            return_value=mock_provider_config,
+        ),
+        patch(
+            "litellm.images.main._get_ImageEditRequestUtils",
+            return_value=mock_utils,
+        ),
+    ):
+        litellm.image_edit(
+            model="openrouter/gpt-image-1",
+            image=mock_image,
+            prompt="a cute sea otter",
+            image_config={"style": "vivid"},
+            api_key="fake-key",
+        )
+
+    forwarded = captured.get("image_edit_optional_request_params", {})
+    assert "image_config" in forwarded, (
+        f"Provider-specific kwargs not forwarded to fallback handler. "
+        f"Got image_edit_optional_request_params={forwarded!r}. "
+        f"Expected 'image_config' to be present (regression: gh-30814)."
+    )
+    assert forwarded["image_config"] == {"style": "vivid"}