[CI][MCP][Harmony] Heavy refactoring Harmony & MCP response tests and stabilizing with deterministic test infrastructure

tests/entrypoints/openai/responses/conftest.py

@@ -1,7 +1,22 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+from __future__ import annotations
+
+import json
+import logging
+from collections.abc import Callable
+from typing import Any
+
 import pytest
 
+logger = logging.getLogger(__name__)
+
+BASE_TEST_ENV = {
+    # The day vLLM said "hello world" on arxiv 🚀
+    "VLLM_GPT_OSS_SYSTEM_START_DATE": "2023-09-12",
+}
+DEFAULT_MAX_RETRIES = 3
+
 
 @pytest.fixture
 def pairs_of_event_types() -> dict[str, str]:
@@ -28,3 +43,159 @@ def pairs_of_event_types() -> dict[str, str]:
     }
     # fmt: on
     return event_pairs
+
+
+async def retry_for_tool_call(
+    client,
+    *,
+    model: str,
+    expected_tool_type: str = "function_call",
+    max_retries: int = DEFAULT_MAX_RETRIES,
+    **create_kwargs: Any,
+):
+    """Call ``client.responses.create`` up to *max_retries* times, returning
+    the first response that contains an output item of *expected_tool_type*.
+
+    Returns the **last** response if none match so the caller's assertions
+    fire with a clear diagnostic.
+    """
+    last_response = None
+    for attempt in range(max_retries):
+        response = await client.responses.create(model=model, **create_kwargs)
+        last_response = response
+        if any(
+            getattr(item, "type", None) == expected_tool_type
+            for item in response.output
+        ):
+            return response
+    assert last_response is not None
+    return last_response
+
+
+async def retry_streaming_for(
+    client,
+    *,
+    model: str,
+    validate_events: Callable[[list], bool],
+    max_retries: int = DEFAULT_MAX_RETRIES,
+    **create_kwargs: Any,
+) -> list:
+    """Call ``client.responses.create(stream=True)`` up to *max_retries*
+    times, returning the first event list where *validate_events* returns
+    ``True``.
+    """
+    last_events: list = []
+    for attempt in range(max_retries):
+        stream = await client.responses.create(
+            model=model, stream=True, **create_kwargs
+        )
+        events: list = []
+        async for event in stream:
+            events.append(event)
+        last_events = events
+        if validate_events(events):
+            return events
+    return last_events
+
+
+def has_output_type(response, type_name: str) -> bool:
+    """Return True if *response* has at least one output item of *type_name*."""
+    return any(getattr(item, "type", None) == type_name for item in response.output)
+
+
+def events_contain_type(events: list, type_substring: str) -> bool:
+    """Return True if any event's type contains *type_substring*."""
+    return any(type_substring in getattr(e, "type", "") for e in events)
+
+
+def validate_streaming_event_stack(
+    events: list, pairs_of_event_types: dict[str, str]
+) -> None:
+    """Validate that streaming events are properly nested/paired."""
+    stack: list[str] = []
+    for event in events:
+        etype = event.type
+        if etype == "response.created":
+            stack.append(etype)
+        elif etype == "response.completed":
+            assert stack and stack[-1] == pairs_of_event_types[etype], (
+                f"Unexpected stack top for {etype}: "
+                f"got {stack[-1] if stack else '<empty>'}"
+            )
+            stack.pop()
+        elif etype.endswith("added") or etype == "response.mcp_call.in_progress":
+            stack.append(etype)
+        elif etype.endswith("delta"):
+            if stack and stack[-1] == etype:
+                continue
+            stack.append(etype)
+        elif etype.endswith("done") or etype == "response.mcp_call.completed":
+            assert etype in pairs_of_event_types, f"Unknown done event: {etype}"
+            expected_start = pairs_of_event_types[etype]
+            assert stack and stack[-1] == expected_start, (
+                f"Stack mismatch for {etype}: "
+                f"expected {expected_start}, "
+                f"got {stack[-1] if stack else '<empty>'}"
+            )
+            stack.pop()
+    assert len(stack) == 0, f"Unclosed events on stack: {stack}"
+
+
+def log_response_diagnostics(
+    response,
+    *,
+    label: str = "Response Diagnostics",
+) -> dict[str, Any]:
+    """Extract and log diagnostic info from a Responses API response.
+
+    Logs reasoning, tool-call attempts, MCP items, and output types so
+    that CI output (``pytest -s`` or ``--log-cli-level=INFO``) gives
+    full visibility into model behaviour even on passing runs.
+
+    Returns the extracted data so callers can make additional assertions
+    if needed.
+    """
+    reasoning_texts = [
+        text
+        for item in response.output
+        if getattr(item, "type", None) == "reasoning"
+        for content in getattr(item, "content", [])
+        if (text := getattr(content, "text", None))
+    ]
+
+    tool_call_attempts = [
+        {
+            "recipient": msg.get("recipient"),
+            "channel": msg.get("channel"),
+        }
+        for msg in response.output_messages
+        if (msg.get("recipient") or "").startswith("python")
+    ]
+
+    mcp_items = [
+        {
+            "name": getattr(item, "name", None),
+            "status": getattr(item, "status", None),
+        }
+        for item in response.output
+        if getattr(item, "type", None) == "mcp_call"
+    ]
+
+    output_types = [getattr(o, "type", None) for o in response.output]
+
+    diagnostics = {
+        "model_attempted_tool_calls": bool(tool_call_attempts),
+        "tool_call_attempts": tool_call_attempts,
+        "mcp_items": mcp_items,
+        "reasoning": reasoning_texts,
+        "output_text": response.output_text,
+        "output_types": output_types,
+    }
+
+    logger.info(
+        "\n====== %s ======\n%s\n==============================",
+        label,
+        json.dumps(diagnostics, indent=2, default=str),
+    )
+
+    return diagnostics