test(verification): add streaming tool calling test (#1933)

# What does this PR do?


## Test Plan

---
[//]: # (BEGIN SAPLING FOOTER)
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* #1934
* __->__ #1933

tests/verifications/openai_api/test_chat_completion.py

@@ -4,6 +4,7 @@
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
 
+import json
 import re
 from typing import Any
 
@@ -225,6 +226,60 @@ def test_chat_non_streaming_tool_calling(request, openai_client, model, provider
     # TODO: add detailed type validation
 
 
+@pytest.mark.parametrize(
+    "case",
+    chat_completion_test_cases["test_tool_calling"]["test_params"]["case"],
+    ids=case_id_generator,
+)
+def test_chat_streaming_tool_calling(request, openai_client, model, provider, verification_config, case):
+    test_name_base = get_base_test_name(request)
+    if should_skip_test(verification_config, provider, model, test_name_base):
+        pytest.skip(f"Skipping {test_name_base} for model {model} on provider {provider} based on config.")
+
+    stream = openai_client.chat.completions.create(
+        model=model,
+        messages=case["input"]["messages"],
+        tools=case["input"]["tools"],
+        stream=True,
+    )
+
+    # Accumulate partial tool_calls here
+    tool_calls_buffer = {}
+    current_id = None
+    # Process streaming chunks
+    for chunk in stream:
+        choice = chunk.choices[0]
+        delta = choice.delta
+
+        if delta.tool_calls is None:
+            continue
+
+        for tool_call_delta in delta.tool_calls:
+            if tool_call_delta.id:
+                current_id = tool_call_delta.id
+            call_id = current_id
+            func_delta = tool_call_delta.function
+
+            if call_id not in tool_calls_buffer:
+                tool_calls_buffer[call_id] = {
+                    "id": call_id,
+                    "type": tool_call_delta.type,
+                    "name": func_delta.name,
+                    "arguments": "",
+                }
+
+            if func_delta.arguments:
+                tool_calls_buffer[call_id]["arguments"] += func_delta.arguments
+
+    assert len(tool_calls_buffer) == 1
+    for call in tool_calls_buffer.values():
+        assert len(call["id"]) > 0
+        assert call["name"] == "get_weather"
+
+        args_dict = json.loads(call["arguments"])
+        assert "san francisco" in args_dict["location"].lower()
+
+
 # --- Helper functions (structured output validation) ---