[Chore]: Stream tokens vs characters in tool call parser tests (#26513)

Signed-off-by: Ben Browning <bbrownin@redhat.com>

tests/entrypoints/openai/tool_parsers/conftest.py

+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+import pytest
+from transformers import AutoTokenizer
+
+from vllm.transformers_utils.tokenizer import AnyTokenizer
+
+
+@pytest.fixture(scope="function")
+def default_tokenizer() -> AnyTokenizer:
+    return AutoTokenizer.from_pretrained("gpt2")

tests/entrypoints/openai/tool_parsers/test_llama3_json_tool_parser.py

@@ -2,17 +2,15 @@
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
 import pytest
-from transformers import AutoTokenizer
 
 from vllm.entrypoints.openai.protocol import ExtractedToolCallInformation
 from vllm.entrypoints.openai.tool_parsers.llama_tool_parser import Llama3JsonToolParser
+from vllm.transformers_utils.tokenizer import AnyTokenizer
 
 
 @pytest.fixture
-def parser():
-    # Use a small tokenizer for testing
-    tokenizer = AutoTokenizer.from_pretrained("gpt2")
-    return Llama3JsonToolParser(tokenizer)
+def parser(default_tokenizer: AnyTokenizer):
+    return Llama3JsonToolParser(default_tokenizer)
 
 
 def test_extract_tool_calls_simple(parser):

tests/entrypoints/openai/tool_parsers/test_llama4_pythonic_tool_parser.py

@@ -11,6 +11,7 @@ from tests.entrypoints.openai.tool_parsers.utils import (
 )
 from vllm.entrypoints.openai.protocol import FunctionCall
 from vllm.entrypoints.openai.tool_parsers import ToolParser, ToolParserManager
+from vllm.transformers_utils.tokenizer import AnyTokenizer
 
 # Test cases similar to pythonic parser but with Llama4 specific format
 SIMPLE_FUNCTION_OUTPUT = "[get_weather(city='LA', metric='C')]"
@@ -63,10 +64,9 @@ PYTHON_TAG_FUNCTION_OUTPUT = (
 
 
 @pytest.mark.parametrize("streaming", [True, False])
-def test_no_tool_call(streaming: bool):
-    mock_tokenizer = MagicMock()
+def test_no_tool_call(streaming: bool, default_tokenizer: AnyTokenizer):
     tool_parser: ToolParser = ToolParserManager.get_tool_parser("llama4_pythonic")(
-        mock_tokenizer
+        default_tokenizer
     )
     model_output = "How can I help you today?"
 
@@ -205,11 +205,13 @@ TEST_CASES = [
 
 @pytest.mark.parametrize("streaming, model_output, expected_tool_calls", TEST_CASES)
 def test_tool_call(
-    streaming: bool, model_output: str, expected_tool_calls: list[FunctionCall]
+    streaming: bool,
+    model_output: str,
+    expected_tool_calls: list[FunctionCall],
+    default_tokenizer: AnyTokenizer,
 ):
-    mock_tokenizer = MagicMock()
     tool_parser: ToolParser = ToolParserManager.get_tool_parser("llama4_pythonic")(
-        mock_tokenizer
+        default_tokenizer
     )
 
     content, tool_calls = run_tool_extraction(
@@ -222,10 +224,9 @@ def test_tool_call(
         assert actual.function == expected
 
 
-def test_streaming_tool_call_with_large_steps():
-    mock_tokenizer = MagicMock()
+def test_streaming_tool_call_with_large_steps(default_tokenizer: AnyTokenizer):
     tool_parser: ToolParser = ToolParserManager.get_tool_parser("llama4_pythonic")(
-        mock_tokenizer
+        default_tokenizer
     )
     model_output_deltas = [
         "<|python_start|>[get_weather(city='LA', metric='C'), "
@@ -245,11 +246,10 @@ def test_streaming_tool_call_with_large_steps():
 
 
 @pytest.mark.parametrize("streaming", [False])
-def test_regex_timeout_handling(streaming: bool):
+def test_regex_timeout_handling(streaming: bool, default_tokenizer: AnyTokenizer):
     """test regex timeout is handled gracefully"""
-    mock_tokenizer = MagicMock()
     tool_parser: ToolParser = ToolParserManager.get_tool_parser("llama4_pythonic")(
-        mock_tokenizer
+        default_tokenizer
     )
 
     fake_problematic_input = "hello world[A(A=" + "\t)A(A=,\t" * 2

tests/entrypoints/openai/tool_parsers/test_olmo3_tool_parser.py

@@ -11,6 +11,7 @@ from tests.entrypoints.openai.tool_parsers.utils import (
 )
 from vllm.entrypoints.openai.protocol import FunctionCall
 from vllm.entrypoints.openai.tool_parsers import ToolParser, ToolParserManager
+from vllm.transformers_utils.tokenizer import AnyTokenizer
 
 # https://github.com/meta-llama/llama-models/blob/main/models/llama3_2/text_prompt_format.md#model-response-format-1
 SIMPLE_FUNCTION_OUTPUT = "get_weather(city='San Francisco', metric='celsius')"
@@ -68,9 +69,10 @@ ESCAPED_STRING_FUNCTION_CALL = FunctionCall(
 
 
 @pytest.mark.parametrize("streaming", [True, False])
-def test_no_tool_call(streaming: bool):
-    mock_tokenizer = MagicMock()
-    tool_parser: ToolParser = ToolParserManager.get_tool_parser("olmo3")(mock_tokenizer)
+def test_no_tool_call(streaming: bool, default_tokenizer: AnyTokenizer):
+    tool_parser: ToolParser = ToolParserManager.get_tool_parser("olmo3")(
+        default_tokenizer
+    )
     model_output = "How can I help you today?"
 
     content, tool_calls = run_tool_extraction(
@@ -183,10 +185,14 @@ TEST_CASES = [
 
 @pytest.mark.parametrize("streaming, model_output, expected_tool_calls", TEST_CASES)
 def test_tool_call(
-    streaming: bool, model_output: str, expected_tool_calls: list[FunctionCall]
+    streaming: bool,
+    model_output: str,
+    expected_tool_calls: list[FunctionCall],
+    default_tokenizer: AnyTokenizer,
 ):
-    mock_tokenizer = MagicMock()
-    tool_parser: ToolParser = ToolParserManager.get_tool_parser("olmo3")(mock_tokenizer)
+    tool_parser: ToolParser = ToolParserManager.get_tool_parser("olmo3")(
+        default_tokenizer
+    )
 
     content, tool_calls = run_tool_extraction(
         tool_parser, model_output, streaming=streaming
@@ -199,9 +205,10 @@ def test_tool_call(
         assert actual.function == expected
 
 
-def test_streaming_tool_call_with_large_steps():
-    mock_tokenizer = MagicMock()
-    tool_parser: ToolParser = ToolParserManager.get_tool_parser("olmo3")(mock_tokenizer)
+def test_streaming_tool_call_with_large_steps(default_tokenizer: AnyTokenizer):
+    tool_parser: ToolParser = ToolParserManager.get_tool_parser("olmo3")(
+        default_tokenizer
+    )
     model_output_deltas = [
         "<function_calls>get_weather(city='San",
         " Francisco', metric='celsius')\n"
@@ -221,10 +228,11 @@ def test_streaming_tool_call_with_large_steps():
 
 
 @pytest.mark.parametrize("streaming", [False])
-def test_regex_timeout_handling(streaming: bool):
+def test_regex_timeout_handling(streaming: bool, default_tokenizer: AnyTokenizer):
     """test regex timeout is handled gracefully"""
-    mock_tokenizer = MagicMock()
-    tool_parser: ToolParser = ToolParserManager.get_tool_parser("olmo3")(mock_tokenizer)
+    tool_parser: ToolParser = ToolParserManager.get_tool_parser("olmo3")(
+        default_tokenizer
+    )
 
     fake_problematic_input = "hello world[A(A=" + "\t)A(A=,\t" * 2
 

tests/entrypoints/openai/tool_parsers/test_pythonic_tool_parser.py

@@ -11,6 +11,7 @@ from tests.entrypoints.openai.tool_parsers.utils import (
 )
 from vllm.entrypoints.openai.protocol import FunctionCall
 from vllm.entrypoints.openai.tool_parsers import ToolParser, ToolParserManager
+from vllm.transformers_utils.tokenizer import AnyTokenizer
 
 # https://github.com/meta-llama/llama-models/blob/main/models/llama3_2/text_prompt_format.md#model-response-format-1
 SIMPLE_FUNCTION_OUTPUT = "get_weather(city='San Francisco', metric='celsius')"
@@ -60,10 +61,9 @@ ESCAPED_STRING_FUNCTION_CALL = FunctionCall(
 
 
 @pytest.mark.parametrize("streaming", [True, False])
-def test_no_tool_call(streaming: bool):
-    mock_tokenizer = MagicMock()
+def test_no_tool_call(streaming: bool, default_tokenizer: AnyTokenizer):
     tool_parser: ToolParser = ToolParserManager.get_tool_parser("pythonic")(
-        mock_tokenizer
+        default_tokenizer
     )
     model_output = "How can I help you today?"
 
@@ -165,11 +165,13 @@ TEST_CASES = [
 
 @pytest.mark.parametrize("streaming, model_output, expected_tool_calls", TEST_CASES)
 def test_tool_call(
-    streaming: bool, model_output: str, expected_tool_calls: list[FunctionCall]
+    streaming: bool,
+    model_output: str,
+    expected_tool_calls: list[FunctionCall],
+    default_tokenizer: AnyTokenizer,
 ):
-    mock_tokenizer = MagicMock()
     tool_parser: ToolParser = ToolParserManager.get_tool_parser("pythonic")(
-        mock_tokenizer
+        default_tokenizer
     )
 
     content, tool_calls = run_tool_extraction(
@@ -183,10 +185,9 @@ def test_tool_call(
         assert actual.function == expected
 
 
-def test_streaming_tool_call_with_large_steps():
-    mock_tokenizer = MagicMock()
+def test_streaming_tool_call_with_large_steps(default_tokenizer: AnyTokenizer):
     tool_parser: ToolParser = ToolParserManager.get_tool_parser("pythonic")(
-        mock_tokenizer
+        default_tokenizer
     )
     model_output_deltas = [
         "[get_weather(city='San",
@@ -207,11 +208,10 @@ def test_streaming_tool_call_with_large_steps():
 
 
 @pytest.mark.parametrize("streaming", [False])
-def test_regex_timeout_handling(streaming: bool):
+def test_regex_timeout_handling(streaming: bool, default_tokenizer: AnyTokenizer):
     """test regex timeout is handled gracefully"""
-    mock_tokenizer = MagicMock()
     tool_parser: ToolParser = ToolParserManager.get_tool_parser("pythonic")(
-        mock_tokenizer
+        default_tokenizer
     )
 
     fake_problematic_input = "hello world[A(A=" + "\t)A(A=,\t" * 2

tests/entrypoints/openai/tool_parsers/utils.py

@@ -11,6 +11,7 @@ from vllm.entrypoints.openai.protocol import (
     ToolCall,
 )
 from vllm.entrypoints.openai.tool_parsers import ToolParser
+from vllm.transformers_utils.tokenizer import AnyTokenizer
 
 
 class StreamingToolReconstructor:
@@ -110,12 +111,32 @@ def run_tool_extraction_nonstreaming(
     return tool_parser.extract_tool_calls(model_output, request)
 
 
+def split_string_into_token_deltas(tokenizer: AnyTokenizer, text: str) -> list[str]:
+    # Split a string into a series of deltas using the provided tokenizer. Each
+    # delta will be the string equivalent of a single token.
+    token_ids = tokenizer.encode(text, add_special_tokens=False)
+    previously_decoded_text = ""
+    deltas = []
+    for i in range(1, len(token_ids) + 1):
+        current_tokens = token_ids[:i]
+        current_text = tokenizer.decode(current_tokens)
+        new_text = current_text[len(previously_decoded_text) :]
+        previously_decoded_text = current_text
+        deltas.append(new_text)
+    return deltas
+
+
 def run_tool_extraction_streaming(
     tool_parser: ToolParser,
     model_deltas: Iterable[str],
     request: ChatCompletionRequest | None = None,
     assert_one_tool_per_delta: bool = True,
 ) -> StreamingToolReconstructor:
+    if isinstance(model_deltas, str):
+        model_deltas = split_string_into_token_deltas(
+            tool_parser.model_tokenizer, model_deltas
+        )
+
     request = request or ChatCompletionRequest(messages=[], model="test-model")
     reconstructor = StreamingToolReconstructor(
         assert_one_tool_per_delta=assert_one_tool_per_delta