[CI/Build] Use Common Event Map Fixture in Harmony / MCP Server Tests (#32531)

Signed-off-by: Alex-Brooks <Alex.Brooks@ibm.com>

tests/entrypoints/openai/responses/conftest.py

@@ -0,0 +1,30 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+import pytest
+
+
+@pytest.fixture
+def pairs_of_event_types() -> dict[str, str]:
+    """Links the 'done' event type with the corresponding 'start' event type.
+
+    This mapping should link all done <-> start events; if tests mean to
+    restrict the allowed events, they should filter this fixture to avoid
+    copy + paste errors in the mappings or unexpected KeyErrors due to missing
+    events.
+    """
+    # fmt: off
+    event_pairs = {
+        "response.completed": "response.created",
+        "response.output_item.done": "response.output_item.added",
+        "response.content_part.done": "response.content_part.added",
+        "response.output_text.done": "response.output_text.delta",
+        "response.reasoning_text.done": "response.reasoning_text.delta",
+        "response.reasoning_part.done": "response.reasoning_part.added",
+        "response.mcp_call_arguments.done": "response.mcp_call_arguments.delta",
+        "response.mcp_call.completed": "response.mcp_call.in_progress",
+        "response.function_call_arguments.done": "response.function_call_arguments.delta", # noqa: E501
+        "response.code_interpreter_call_code.done": "response.code_interpreter_call_code.delta", # noqa: E501
+        "response.web_search_call.completed": "response.web_search_call.in_progress",
+    }
+    # fmt: on
+    return event_pairs