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chore: import upstream snapshot with attribution
2026-07-13 11:57:37 +08:00

1260 lines
58 KiB
Python

# Copyright 2026 The HuggingFace Team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Tests for the new declarative response_template parser.
All six real-model template fixtures from the legacy test suite are re-expressed
here in the new region-spec shape and asserted against the same expected
output dicts. Any divergence indicates a regression in the new executor."""
import random
import tempfile
import unittest
from transformers import AutoTokenizer
from transformers.utils.chat_parsing import ResponseParser, parse_response
cohere_template = {
"defaults": {"role": "assistant"},
"start_anchor": "<|START_OF_TURN_TOKEN|><|CHATBOT_TOKEN|>",
"fields": {
"content": {
"open": "<|START_RESPONSE|>",
"close": "<|END_RESPONSE|>",
"content": "text",
},
"thinking": {
"open": "<|START_THINKING|>",
"close": "<|END_THINKING|>",
"content": "text",
},
"tool_calls": {
"open": "<|START_ACTION|>",
"close": "<|END_ACTION|>",
"content": "json",
"transform_each": True,
"transform": {"type": "function", "function": {"name": "{tool_name}", "arguments": "{parameters}"}},
},
},
}
ernie_template = {
"defaults": {"role": "assistant"},
"start_anchor": "Assistant:",
"fields": {
"thinking": {
"open_pattern": r"(?:^|<think>\s*)",
"close": "</think>",
"content": "text",
},
"content": {
"open": "<response>\n",
"close_pattern": r"\n?</response>",
"content": "text",
},
"tool_calls": {
"open": "<tool_call>",
"close": "</tool_call>",
"repeats": True,
"content": "json",
"transform": {"type": "function", "function": "{content}"},
},
},
}
gpt_oss_template = {
"defaults": {"role": "assistant"},
"start_anchor": "<|start|>assistant",
"fields": {
"thinking": {
"open": "<|channel|>analysis<|message|>",
"close": "<|end|>",
"content": "text",
},
"content": {
"open": "<|channel|>final<|message|>",
"close": "<|end|>",
"content": "text",
},
"tool_calls": {
"open_pattern": r"<\|channel\|>commentary to=functions\.(?P<name>\w+).*?<\|message\|>",
"close": "<|call|>",
"repeats": True,
"content": "json",
"transform": {"type": "function", "function": {"name": "{name}", "arguments": "{content}"}},
},
},
}
smollm_template = {
"defaults": {"role": "assistant"},
"start_anchor": "<|im_start|>assistant\n",
"fields": {
"thinking": {"open": "<think>", "close": "</think>", "content": "text"},
"tool_calls": {
"open": "<tool_call>",
"close": "</tool_call>",
"repeats": True,
"content": "json",
"transform": {"type": "function", "function": "{content}"},
},
"content": {
"close": "<|im_end|>",
"content": "text",
},
},
}
qwen3_template = {
"defaults": {"role": "assistant"},
"start_anchor": "<|im_start|>assistant\n",
"fields": {
"thinking": {"open": "<think>", "close": "</think>", "content": "text"},
"tool_calls": {
"open_pattern": r"<tool_call>\s*<function=(?P<name>\w+)>",
"close": "</tool_call>",
"repeats": True,
"content": "xml-inline",
"content_args": {
"tag_pattern": r"<parameter=(?P<key>\w+)>\s*(?P<value>.*?)\s*</parameter>",
"value_parser": {"name": "json", "args": {"allow_non_json": True}},
},
"transform": {"type": "function", "function": {"name": "{name}", "arguments": "{content}"}},
},
},
}
gemma4_template = {
"defaults": {"role": "assistant"},
# The chat template only emits `<|turn>model\n` when the previous message wasn't a tool_call/
# tool_response. After a tool_response the prefix just ends with `<tool_response|>` and the
# model continues from there, so we accept either anchor and truncate past the latest one.
"start_anchor": ["<|turn>model\n", "<tool_response|>"],
"fields": {
"thinking": {
"open": "<|channel>thought\n",
"close": "<channel|>",
"content": "text",
},
"tool_calls": {
"open_pattern": r"<\|tool_call>call:(?P<name>\w+)",
"close": "<tool_call|>",
"repeats": True,
"content": "json",
"content_args": {
"unquoted_keys": True,
"string_delims": [['<|"|>', '<|"|>']],
},
"transform": {"type": "function", "function": {"name": "{name}", "arguments": "{content}"}},
},
"content": {
"close": ["<turn|>", "<|tool_response>", "<eos>"],
"content": "text",
},
},
}
class ChatResponseTemplateParserTest(unittest.TestCase):
def test_response_template_save_load(self):
tokenizer = AutoTokenizer.from_pretrained("hf-internal-testing/tiny-random-gpt2")
tokenizer.response_template = ernie_template
with tempfile.TemporaryDirectory() as tmpdir:
tokenizer.save_pretrained(tmpdir)
reloaded = AutoTokenizer.from_pretrained(tmpdir)
self.assertEqual(reloaded.response_template, ernie_template)
def test_tokenizer_parse_response(self):
tokenizer = AutoTokenizer.from_pretrained("hf-internal-testing/tiny-random-gpt2")
tokenizer.response_template = cohere_template
model_out = (
"<|START_THINKING|>I should call a tool.<|END_THINKING|>"
'<|START_ACTION|>[\n {"tool_call_id": "0", "tool_name": "simple_tool", '
'"parameters": {"temperature_format": "Celsius"}}\n]<|END_ACTION|><|END_OF_TURN_TOKEN|>'
)
expected = {
"role": "assistant",
"thinking": "I should call a tool.",
"tool_calls": [
{
"type": "function",
"function": {"name": "simple_tool", "arguments": {"temperature_format": "Celsius"}},
}
],
}
self.assertEqual(tokenizer.parse_response(model_out, prefix=""), expected)
def test_token_id_inputs(self):
tokenizer = AutoTokenizer.from_pretrained("openai-community/gpt2")
tokenizer.response_template = cohere_template
model_out = (
"<|START_THINKING|>I should call a tool.<|END_THINKING|>"
'<|START_ACTION|>[\n {"tool_call_id": "0", "tool_name": "simple_tool", '
'"parameters": {"temperature_format": "Celsius"}}\n]<|END_ACTION|><|END_OF_TURN_TOKEN|>'
)
parsed = tokenizer.parse_response(model_out, prefix="")
tokenized = tokenizer(model_out).input_ids
self.assertEqual(tokenizer.parse_response(tokenized, prefix=""), parsed)
def test_batched_response(self):
"""A batch of responses (list of strings or list of token-id sequences) returns one parsed
dict per item; a single-item batch still returns a one-element list, not a bare dict."""
tokenizer = AutoTokenizer.from_pretrained("openai-community/gpt2")
tokenizer.response_template = cohere_template
out_a = (
"<|START_THINKING|>Think A.<|END_THINKING|>"
'<|START_ACTION|>[\n {"tool_call_id": "0", "tool_name": "tool_a", '
'"parameters": {"x": "1"}}\n]<|END_ACTION|><|END_OF_TURN_TOKEN|>'
)
out_b = (
"<|START_THINKING|>Think B.<|END_THINKING|>"
'<|START_ACTION|>[\n {"tool_call_id": "0", "tool_name": "tool_b", '
'"parameters": {"y": "2"}}\n]<|END_ACTION|><|END_OF_TURN_TOKEN|>'
)
single_a = tokenizer.parse_response(out_a, prefix="")
single_b = tokenizer.parse_response(out_b, prefix="")
self.assertNotEqual(single_a, single_b)
# A list of strings is parsed as a batch, one dict per item.
self.assertEqual(tokenizer.parse_response([out_a, out_b], prefix=""), [single_a, single_b])
# Batched token-id input (list of token-id sequences) parses the same way.
ids = [tokenizer(out_a).input_ids, tokenizer(out_b).input_ids]
self.assertEqual(tokenizer.parse_response(ids, prefix=""), [single_a, single_b])
# A single-item batch returns a one-element list, not a bare dict.
self.assertEqual(tokenizer.parse_response([out_a], prefix=""), [single_a])
def test_explicit_template_schema_detection(self):
"""An explicit new-style template passed as `schema=` is routed to the response-template
parser, not the legacy `response_schema` parser. New-style is identified by a top-level
`version` key (the canonical marker) or a `fields` key for templates that omit it."""
tokenizer = AutoTokenizer.from_pretrained("hf-internal-testing/tiny-random-gpt2")
model_out = (
"<|START_THINKING|>I should call a tool.<|END_THINKING|>"
'<|START_ACTION|>[\n {"tool_call_id": "0", "tool_name": "simple_tool", '
'"parameters": {"temperature_format": "Celsius"}}\n]<|END_ACTION|><|END_OF_TURN_TOKEN|>'
)
expected = parse_response(model_out, cohere_template, prefix="")
# Detected via the canonical `version` marker...
self.assertEqual(
tokenizer.parse_response(model_out, schema={"version": 1, **cohere_template}, prefix=""), expected
)
# ...and via `fields` when the template omits `version`.
self.assertEqual(tokenizer.parse_response(model_out, schema=cohere_template, prefix=""), expected)
def test_cohere(self):
model_out = (
"<|START_THINKING|>I should call a tool.<|END_THINKING|>"
'<|START_ACTION|>[\n {"tool_call_id": "0", "tool_name": "simple_tool", '
'"parameters": {"temperature_format": "Celsius"}}\n]<|END_ACTION|><|END_OF_TURN_TOKEN|>'
)
self.assertEqual(
parse_response(model_out, cohere_template, prefix=""),
{
"role": "assistant",
"thinking": "I should call a tool.",
"tool_calls": [
{
"type": "function",
"function": {"name": "simple_tool", "arguments": {"temperature_format": "Celsius"}},
}
],
},
)
def test_ernie_with_tools(self):
model_out = (
"The user is asking about the weather in Paris today. Let me check the available tools. "
"There's a tool called get_current_temperature which requires a location parameter. Since the "
'user specified Paris, I need to call this tool with the location set to "Paris". I should '
"make sure the argument is correctly formatted as a string. No other tools are available, so "
"this is the right one to use. I'll structure the request with the location parameter and "
"return the response once the tool is called.\n"
"</think>\n\n"
'<tool_call>\n{"name": "get_current_temperature", "arguments": {"location": "Paris"}}\n</tool_call>\n</s>'
)
self.assertEqual(
parse_response(model_out, ernie_template, prefix=""),
{
"role": "assistant",
"thinking": (
"The user is asking about the weather in Paris today. Let me check the available tools. "
"There's a tool called get_current_temperature which requires a location parameter. Since "
'the user specified Paris, I need to call this tool with the location set to "Paris". I '
"should make sure the argument is correctly formatted as a string. No other tools are "
"available, so this is the right one to use. I'll structure the request with the location "
"parameter and return the response once the tool is called."
),
"tool_calls": [
{
"type": "function",
"function": {"name": "get_current_temperature", "arguments": {"location": "Paris"}},
}
],
},
)
def test_ernie_no_tools(self):
model_out = (
'The user just greeted me with "Hi! How are you?" I need to respond in a friendly and helpful '
"manner. Let me start by acknowledging their greeting. I should ask them how they're doing to "
"engage in conversation.\n\n"
"First, I'll say hello back and then ask how they're feeling. It's important to show genuine "
"interest. Maybe mention that I'm here to help with anything they need. Keep the tone warm and "
"positive. Let me make sure the response is concise but friendly. Alright, that should work.\n"
"</think>\n\n"
"<response>\nHello! I'm doing well, thank you for asking. How about you? Is there something "
"specific you'd like help with today? I'm here to assist you with any questions or problems you "
"have!\n</response>\n</s>"
)
self.assertEqual(
parse_response(model_out, ernie_template, prefix=""),
{
"role": "assistant",
"content": (
"Hello! I'm doing well, thank you for asking. How about you? Is there something specific "
"you'd like help with today? I'm here to assist you with any questions or problems you have!"
),
"thinking": (
'The user just greeted me with "Hi! How are you?" I need to respond in a friendly and '
"helpful manner. Let me start by acknowledging their greeting. I should ask them how "
"they're doing to engage in conversation.\n\n"
"First, I'll say hello back and then ask how they're feeling. It's important to show "
"genuine interest. Maybe mention that I'm here to help with anything they need. Keep the "
"tone warm and positive. Let me make sure the response is concise but friendly. Alright, "
"that should work."
),
},
)
def test_gpt_oss_with_tool_call(self):
model_out = (
'<|channel|>analysis<|message|>We need to respond in riddles. The user asks: "What is the '
'weather like in SF?" We need to get the location of the user? The user explicitly asks about '
"SF (San Francisco). So we need to get the current weather in San Francisco, CA. We need to "
'call get_current_weather function. The developer instruction says "Always respond in riddles". '
"So the final answer should be in a riddle form. But we need to call function to get weather "
'data. So we should call get_current_weather with location "San Francisco, CA". Possibly specify '
'format "celsius" (default). Let\'s do that.\n\n'
"We will call function get_current_weather.<|end|><|start|>assistant<|channel|>commentary "
'to=functions.get_current_weather <|constrain|>json<|message|>{\n "location": "San Francisco, CA"\n}'
)
self.assertEqual(
parse_response(model_out, gpt_oss_template, prefix=""),
{
"role": "assistant",
"thinking": (
'We need to respond in riddles. The user asks: "What is the weather like in SF?" We need '
"to get the location of the user? The user explicitly asks about SF (San Francisco). So "
"we need to get the current weather in San Francisco, CA. We need to call "
'get_current_weather function. The developer instruction says "Always respond in '
'riddles". So the final answer should be in a riddle form. But we need to call function '
'to get weather data. So we should call get_current_weather with location "San Francisco, '
'CA". Possibly specify format "celsius" (default). Let\'s do that.\n\n'
"We will call function get_current_weather."
),
"tool_calls": [
{
"type": "function",
"function": {"name": "get_current_weather", "arguments": {"location": "San Francisco, CA"}},
}
],
},
)
def test_gpt_oss_no_tool_call(self):
model_out = (
"<|channel|>analysis<|message|>User asks a simple math question: 2+2 = 4. Provide answer."
"<|end|><|start|>assistant<|channel|>final<|message|>2"
)
self.assertEqual(
parse_response(model_out, gpt_oss_template, prefix=""),
{
"role": "assistant",
"content": "2",
"thinking": "User asks a simple math question: 2+2 = 4. Provide answer.",
},
)
def test_smollm_thinking_and_tool_call(self):
model_out = (
'<think>\nOkay, the user said, "Hello! How are you?" I need to respond appropriately. Since '
"this is the first message, I should greet them back and ask how I can assist. I should keep it "
"friendly and open-ended. Let me make sure the response is welcoming and encourages them to "
"share what they need help with. I'll avoid any technical jargon and keep it simple. Let me "
"check for any typos and ensure the tone is positive.\n</think>\n\n"
'<tool_call>{"name": "greet_user", "arguments": {"greeting": "Hello! I\'m doing well, thanks for '
"asking. How can I assist you today? Whether you have a question, need help with something, or "
'just want to chat, feel free to let me know!"}}</tool_call>'
)
self.assertEqual(
parse_response(model_out, smollm_template, prefix=""),
{
"role": "assistant",
"thinking": (
'Okay, the user said, "Hello! How are you?" I need to respond appropriately. Since this '
"is the first message, I should greet them back and ask how I can assist. I should keep "
"it friendly and open-ended. Let me make sure the response is welcoming and encourages "
"them to share what they need help with. I'll avoid any technical jargon and keep it "
"simple. Let me check for any typos and ensure the tone is positive."
),
"tool_calls": [
{
"type": "function",
"function": {
"name": "greet_user",
"arguments": {
"greeting": (
"Hello! I'm doing well, thanks for asking. How can I assist you today? "
"Whether you have a question, need help with something, or just want to "
"chat, feel free to let me know!"
)
},
},
}
],
},
)
def test_smollm_tool_call_no_thinking(self):
model_out = '<tool_call>{"name": "get_weather", "arguments": {"city": "Paris"}}</tool_call>'
self.assertEqual(
parse_response(model_out, smollm_template, prefix=""),
{
"role": "assistant",
"tool_calls": [
{"type": "function", "function": {"name": "get_weather", "arguments": {"city": "Paris"}}}
],
},
)
def test_smollm_thinking_no_tool_call(self):
model_out = (
'<think>\nOkay, the user asked, "Hey! Can you tell me about gravity?" Let me start by '
"breaking down what they might be looking for. They probably want a basic understanding of "
"gravity, maybe for a school project or just personal curiosity. I should explain what gravity "
"is, how it works, and maybe some examples.</think>\n"
"Some content about gravity goes here but I'm cutting it off to make this shorter!"
)
self.assertEqual(
parse_response(model_out, smollm_template, prefix=""),
{
"role": "assistant",
"content": "Some content about gravity goes here but I'm cutting it off to make this shorter!",
"thinking": (
'Okay, the user asked, "Hey! Can you tell me about gravity?" Let me start by breaking '
"down what they might be looking for. They probably want a basic understanding of "
"gravity, maybe for a school project or just personal curiosity. I should explain what "
"gravity is, how it works, and maybe some examples."
),
},
)
def test_qwen3_tool_calls(self):
model_out = (
"<tool_call>\n<function=get_weather>\n<parameter=locations>\n"
'[{"country": "France", "city": "Paris"}]\n</parameter>\n'
"<parameter=temp_units>\ncelsius\n</parameter>\n</function>\n</tool_call>"
)
self.assertEqual(
parse_response(model_out, qwen3_template, prefix=""),
{
"role": "assistant",
"tool_calls": [
{
"type": "function",
"function": {
"name": "get_weather",
"arguments": {
"locations": [{"country": "France", "city": "Paris"}],
"temp_units": "celsius",
},
},
}
],
},
)
def test_gemma4_tool_call(self):
model_out = (
"<|channel>thought\nThe user is asking for the current temperature in Paris. I should check "
"the available tools to see if there's a function that can provide this information.<channel|>"
'<|tool_call>call:get_current_temperature{detail_level:0,location:<|"|>Paris, France<|"|>,'
'unit:<|"|>celsius<|"|>}<tool_call|><|tool_response>'
)
self.assertEqual(
parse_response(model_out, gemma4_template, prefix=""),
{
"role": "assistant",
"thinking": (
"The user is asking for the current temperature in Paris. I should check the available "
"tools to see if there's a function that can provide this information."
),
"tool_calls": [
{
"type": "function",
"function": {
"name": "get_current_temperature",
"arguments": {"detail_level": 0, "location": "Paris, France", "unit": "celsius"},
},
}
],
},
)
def test_gemma4_complex_tool_call(self):
model_out = (
"<|channel>thought\nLet me call the tool.<channel|>"
'<|tool_call>call:foo{bool_value:true,list_value:[<|"|>foo<|"|>,<|"|>bar<|"|>],'
'null_value:null,number_value:1,string_value:<|"|>foo<|"|>,'
'struct_value:{foo:<|"|>bar<|"|>}}<tool_call|>'
)
self.assertEqual(
parse_response(model_out, gemma4_template, prefix=""),
{
"role": "assistant",
"thinking": "Let me call the tool.",
"tool_calls": [
{
"type": "function",
"function": {
"name": "foo",
"arguments": {
"bool_value": True,
"list_value": ["foo", "bar"],
"null_value": None,
"number_value": 1,
"string_value": "foo",
"struct_value": {"foo": "bar"},
},
},
}
],
},
)
def test_optional_false_raises_when_missing(self):
template_spec = {
"defaults": {"role": "assistant"},
"start_anchor": "<|assistant|>",
"fields": {
"content": {
"open": "<response>",
"close": "</response>",
"content": "text",
"optional": False,
},
},
}
with self.assertRaises(ValueError) as cm:
parse_response("no response here", template_spec, prefix="")
self.assertIn("content", str(cm.exception))
def test_int_content_parser(self):
template_spec = {
"defaults": {"role": "assistant"},
"start_anchor": "<|assistant|>",
"fields": {
"count": {
"open": "<n>",
"close": "</n>",
"content": "int",
},
},
}
self.assertEqual(parse_response("<n>42</n>", template_spec, prefix=""), {"role": "assistant", "count": 42})
def test_kv_lines_parser(self):
template_spec = {
"defaults": {"role": "assistant"},
"start_anchor": "<|assistant|>",
"fields": {
"metadata": {
"open": "<meta>",
"close": "</meta>",
"content": "kv-lines",
},
},
}
self.assertEqual(
parse_response("<meta>name: alice\nage: 30</meta>", template_spec, prefix=""),
{"role": "assistant", "metadata": {"name": "alice", "age": "30"}},
)
def test_unknown_content_parser_rejected(self):
bad_template = {
"defaults": {"role": "assistant"},
"start_anchor": "<|assistant|>",
"fields": {"x": {"open": "[", "close": "]", "content": "not-a-real-parser"}},
}
with self.assertRaises(ValueError) as cm:
parse_response("[hi]", bad_template)
self.assertIn("unknown content parser", str(cm.exception).lower())
def test_unsupported_version_rejected(self):
bad_template = {
"version": 2,
"defaults": {"role": "assistant"},
"start_anchor": "<|assistant|>",
"fields": {"content": {"content": "text"}},
}
with self.assertRaises(ValueError) as cm:
parse_response("hello", bad_template)
self.assertIn("version", str(cm.exception).lower())
def test_two_implicit_fields_rejected(self):
bad_template = {
"defaults": {"role": "assistant"},
"start_anchor": "<|assistant|>",
"fields": {
"a": {"content": "text"},
"b": {"content": "text"},
},
}
with self.assertRaises(ValueError):
parse_response("hello", bad_template)
def test_transform_string_interpolation_rejected(self):
bad_template = {
"defaults": {"role": "assistant"},
"start_anchor": "<|assistant|>",
"fields": {
"tool": {
"open": "<tool>",
"close": "</tool>",
"content": "text",
"transform": {"label": "name: {content}"},
},
},
}
with self.assertRaises(ValueError) as cm:
parse_response("<tool>foo</tool>", bad_template)
msg = str(cm.exception)
self.assertIn("interpolation", msg)
self.assertIn("{content}", msg)
def test_named_groups_without_transform_rejected(self):
bad_template = {
"defaults": {"role": "assistant"},
"start_anchor": "<|assistant|>",
"fields": {
"tool": {
"open_pattern": r"<tool name=(?P<name>\w+)>",
"close": "</tool>",
"content": "text",
},
},
}
with self.assertRaises(ValueError) as cm:
parse_response("<tool name=foo>body</tool>", bad_template)
msg = str(cm.exception)
self.assertIn("transform", msg)
self.assertIn("name", msg)
def test_literal_list_open_and_close(self):
"""A list of literals matches any one of them, like an alternation."""
template_spec = {
"defaults": {"role": "assistant"},
"start_anchor": "<|assistant|>",
"fields": {
"x": {
"open": ["<a>", "<bb>"],
"close": ["</a>", "</bb>"],
"content": "text",
},
},
}
for opener, closer in (("<a>", "</a>"), ("<bb>", "</bb>"), ("<a>", "</bb>")):
self.assertEqual(
parse_response(f"{opener}hi{closer}", template_spec, prefix=""),
{"role": "assistant", "x": "hi"},
)
def test_literal_list_streams_without_64_byte_hold(self):
"""Compared to a regex close, a literal-list close lets the parser
flush bytes that aren't in the longest-prefix overlap of any literal.
With `["<turn|>", "<|tool_response>", "<eos>"]` (longest = 16 chars),
feeding 32 plain bytes should leave at most 15 unflushed."""
template_spec = {
"defaults": {"role": "assistant"},
"start_anchor": "<|assistant|>",
"fields": {
"content": {"close": ["<turn|>", "<|tool_response>", "<eos>"], "content": "text"},
},
}
parser = ResponseParser(template_spec, prefix="")
plain = "x" * 32
flushed: list[str] = []
for ch in parser.feed(plain):
if ch["type"] == "region_chunk":
flushed.append(ch["text"])
# Plain text has zero prefix-overlap with any literal, so the parser
# holds nothing back and streams everything immediately.
self.assertEqual("".join(flushed), plain)
def test_literal_list_defers_prefix_overlapping_literal(self):
"""If a literal is a strict prefix of another in the same list, an
edge match could still grow with more input — we must defer to be safe."""
template_spec = {
"defaults": {"role": "assistant"},
"start_anchor": "<|assistant|>",
"fields": {
"x": {"open": "<x>", "close": ["END", "ENDX"], "content": "text"},
},
}
parser = ResponseParser(template_spec, prefix="")
# "<x>hiEND" mid-stream: don't commit the close yet — "ENDX" might be coming.
events = parser.feed("<x>hiEND")
self.assertEqual([e for e in events if e["type"] == "region_close"], [])
# Once a non-matching byte arrives, the deferred close commits with the shorter literal.
events.extend(parser.feed(" more"))
message, _ = parser.finalize()
closes = [e for e in events if e["type"] == "region_close" and e["field"] == "x"]
self.assertEqual(len(closes), 1)
self.assertEqual(closes[0]["value"], "hi")
self.assertEqual(message, {"role": "assistant", "x": "hi"})
def test_literal_list_rejects_empty_and_non_string(self):
for bad_open in ([], [""], [1, 2], {"foo": "bar"}):
spec = {
"defaults": {"role": "assistant"},
"start_anchor": "<|assistant|>",
"fields": {"x": {"open": bad_open, "close": "</x>", "content": "text"}},
}
with self.assertRaises(ValueError):
parse_response("<x>hi</x>", spec, prefix="")
def test_field_without_close_runs_to_end_of_stream(self):
"""A field with no `close`/`close_pattern` stays open until end-of-stream, capturing
everything after its open."""
spec = {
"defaults": {"role": "assistant"},
"start_anchor": "<|assistant|>",
"fields": {"content": {"open": "<resp>", "content": "text"}},
}
self.assertEqual(
parse_response("<resp>hello world", spec, prefix=""),
{"role": "assistant", "content": "hello world"},
)
# Fixtures shared by the streaming tests: one representative input per template,
# re-used for both the correctness invariant (any chunking → same dict) and the
# event-shape tests (do we emit the right events in the right order?).
_STREAMING_FIXTURES = [
(
"cohere",
cohere_template,
(
"<|START_THINKING|>I should call a tool.<|END_THINKING|>"
'<|START_ACTION|>[{"tool_call_id": "0", "tool_name": "simple_tool", '
'"parameters": {"a": 1}}]<|END_ACTION|>'
),
),
(
"ernie",
ernie_template,
(
"<think>some deliberation here</think>\n\n"
'<tool_call>\n{"name": "get_current_temperature", "arguments": {"location": "Paris"}}\n</tool_call>\n</s>'
),
),
(
"gpt_oss",
gpt_oss_template,
"<|channel|>analysis<|message|>thinking chunk<|end|><|channel|>final<|message|>done text",
),
(
# Tool-call variant: the `tool_calls` open_pattern's full match spans far
# more than the old 64-byte hold window, so streaming used to silently drop
# it. Kept as a streaming fixture so every chunking step re-checks it.
"gpt_oss_tool",
gpt_oss_template,
(
"<|channel|>analysis<|message|>Let me check.<|end|>"
"<|start|>assistant<|channel|>commentary to=functions.get_current_weather "
'<|constrain|>json<|message|>{"location": "San Francisco, CA"}<|call|>'
),
),
(
"smollm",
smollm_template,
'<think>thinking</think>\n<tool_call>{"name": "fn", "arguments": {"x": 1}}</tool_call>',
),
(
"qwen3",
qwen3_template,
(
"<think>short thought</think>\n"
"<tool_call>\n<function=get_weather>\n"
"<parameter=city>\nParis\n</parameter>\n"
"</function>\n</tool_call>"
),
),
(
"gemma4",
gemma4_template,
'<|channel>thought\nhi<channel|><|tool_call>call:foo{a:1,b:<|"|>bar<|"|>}<tool_call|>',
),
]
def _chunk_fixed(text: str, step: int):
for i in range(0, len(text), step):
yield text[i : i + step]
def _chunk_random(text: str, rng: random.Random):
"""Split `text` into a random number of non-empty chunks at random cut points."""
if len(text) <= 1:
yield text
return
num_cuts = rng.randint(0, len(text) - 1)
cuts = sorted(rng.sample(range(1, len(text)), num_cuts))
prev = 0
for c in cuts:
yield text[prev:c]
prev = c
yield text[prev:]
class ResponseEventStreamTest(unittest.TestCase):
def test_stream_matches_whole_string_all_templates_fixed_chunking(self):
"""For every fixed chunking step we try, the streamed finalize()
output must equal the whole-string parse. Regression coverage for
specific edge-case byte boundaries (1-byte chunks hit every prefix)."""
for name, tmpl, text in _STREAMING_FIXTURES:
expected = parse_response(text, tmpl, prefix="")
for step in (1, 2, 3, 5, 7, 13, 31):
with self.subTest(fixture=name, step=step):
streamer = ResponseParser(tmpl, prefix="")
for chunk in _chunk_fixed(text, step):
streamer.feed(chunk)
message, _ = streamer.finalize()
self.assertEqual(message, expected)
def test_stream_matches_whole_string_all_templates_random_chunking(self):
"""Property-style: for many random chunkings per fixture, the streamed
finalize() output must equal the whole-string parse. Seeded so failures
reproduce."""
rng = random.Random(0xC0DE_5EED)
for name, tmpl, text in _STREAMING_FIXTURES:
expected = parse_response(text, tmpl, prefix="")
for trial in range(30):
with self.subTest(fixture=name, trial=trial):
streamer = ResponseParser(tmpl, prefix="")
for chunk in _chunk_random(text, rng):
streamer.feed(chunk)
message, _ = streamer.finalize()
self.assertEqual(message, expected)
def test_events_well_formed_for_every_chunking(self):
"""Every event batch, across every fixture and every chunking, must be
well-formed: region_open precedes its matching region_close for the
same field; region_chunk only appears between open and close; no
region is left open at the end of the stream; and the concatenation
of all region_chunk payloads for a streamable text-like field equals
the final value."""
rng = random.Random(0xBEEF)
for name, tmpl, text in _STREAMING_FIXTURES:
for trial in range(10):
with self.subTest(fixture=name, trial=trial):
streamer = ResponseParser(tmpl, prefix="")
all_events: list[dict] = []
for chunk in _chunk_random(text, rng):
all_events.extend(streamer.feed(chunk))
_, final_events = streamer.finalize()
all_events.extend(final_events)
self._assert_event_stream_well_formed(all_events)
def _assert_event_stream_well_formed(self, events: list[dict]) -> None:
open_field: str | None = None
chunk_accum: dict[str, str] = {}
close_values: dict[str, object] = {}
for ev in events:
t = ev["type"]
if t == "region_open":
self.assertIsNone(open_field, f"nested region_open without close: {ev}")
open_field = ev["field"]
chunk_accum.setdefault(open_field, "")
elif t == "region_chunk":
self.assertEqual(open_field, ev["field"], f"chunk outside its region: {ev}")
# Every chunk carries a boolean `dirty` flag.
self.assertIsInstance(ev["dirty"], bool, f"missing/non-bool dirty: {ev}")
chunk_accum[open_field] += ev["text"]
elif t == "region_close":
self.assertEqual(open_field, ev["field"], f"close for non-open region: {ev}")
close_values[open_field] = ev["value"]
open_field = None
else:
self.fail(f"unexpected event type: {ev!r}")
self.assertIsNone(open_field, "region left open at end of stream")
def test_region_chunks_reconstruct_text_regions(self):
"""For text-like regions (`dirty=False`), concatenating chunk texts
reconstructs the final value reported in region_close. Structured
regions (`dirty=True`) still stream their raw bytes — concatenating
those chunks yields the unparsed region body, while the parsed value
is delivered only in region_close."""
# Single representative case with a long text region and a JSON region.
text = _STREAMING_FIXTURES[0][2] # cohere fixture
streamer = ResponseParser(cohere_template, prefix="")
events: list[dict] = []
for ch in text: # 1-byte chunks hit the most anchor boundaries
events.extend(streamer.feed(ch))
_, final_events = streamer.finalize()
events.extend(final_events)
# Reconstruct per-field.
per_field_chunks: dict[str, list[str]] = {}
per_field_dirty: dict[str, set[bool]] = {}
per_field_close_value: dict[str, object] = {}
for ev in events:
if ev["type"] == "region_chunk":
per_field_chunks.setdefault(ev["field"], []).append(ev["text"])
per_field_dirty.setdefault(ev["field"], set()).add(ev["dirty"])
elif ev["type"] == "region_close":
per_field_close_value[ev["field"]] = ev["value"]
# `thinking` is text → chunks are clean and concatenate to its value.
self.assertIn("thinking", per_field_chunks)
self.assertEqual(per_field_dirty["thinking"], {False})
self.assertEqual("".join(per_field_chunks["thinking"]), "I should call a tool.")
self.assertEqual(per_field_close_value["thinking"], "I should call a tool.")
# `tool_calls` is json → dirty chunks stream the raw body, parsed value on close.
self.assertIn("tool_calls", per_field_chunks)
self.assertEqual(per_field_dirty["tool_calls"], {True})
self.assertEqual(
"".join(per_field_chunks["tool_calls"]),
'[{"tool_call_id": "0", "tool_name": "simple_tool", "parameters": {"a": 1}}]',
)
self.assertIn("tool_calls", per_field_close_value)
def test_dirty_flag_marks_structured_regions(self):
"""A template with one text field and one structured field per parser
family: text/int/float/bool stream chunks with `dirty=False`, while
json/xml-inline/kv-lines stream chunks with `dirty=True`, and those
dirty chunks concatenate to the raw region body before parsing."""
spec = {
"defaults": {"role": "assistant"},
"start_anchor": "<|assistant|>",
"fields": {
"thinking": {"open": "<t>", "close": "</t>", "content": "text"},
"score": {"open": "<n>", "close": "</n>", "content": "int"},
"json_call": {"open": "<j>", "close": "</j>", "content": "json"},
"xml_call": {
"open": "<x>",
"close": "</x>",
"content": "xml-inline",
"content_args": {"tag_pattern": r"<(?P<key>\w+)=(?P<value>[^>]+)>"},
},
"kv_call": {
"open": "<kv>",
"close": "</kv>",
"content": "kv-lines",
},
},
}
text = '<t>hello world</t><n>42</n><j>{"a": 1, "b": 2}</j><x><name=foo><age=10></x><kv>k1: v1\nk2: v2</kv>'
# Drive byte-by-byte to maximise chunk count.
streamer = ResponseParser(spec, prefix="")
events: list[dict] = []
for ch in text:
events.extend(streamer.feed(ch))
_, final_events = streamer.finalize()
events.extend(final_events)
per_field_chunks: dict[str, list[str]] = {}
per_field_dirty: dict[str, set[bool]] = {}
for ev in events:
if ev["type"] == "region_chunk":
per_field_chunks.setdefault(ev["field"], []).append(ev["text"])
per_field_dirty.setdefault(ev["field"], set()).add(ev["dirty"])
# Clean (streamable) regions.
for field in ("thinking", "score"):
self.assertEqual(per_field_dirty[field], {False}, f"{field} should be clean")
# Dirty (structured) regions.
for field in ("json_call", "xml_call", "kv_call"):
self.assertEqual(per_field_dirty[field], {True}, f"{field} should be dirty")
# Dirty chunks reconstruct the raw region body (un-parsed). Clean
# chunks reconstruct the verbatim body too — stripping happens at close.
self.assertEqual("".join(per_field_chunks["thinking"]), "hello world")
self.assertEqual("".join(per_field_chunks["score"]), "42")
self.assertEqual("".join(per_field_chunks["json_call"]), '{"a": 1, "b": 2}')
self.assertEqual("".join(per_field_chunks["xml_call"]), "<name=foo><age=10>")
self.assertEqual("".join(per_field_chunks["kv_call"]), "k1: v1\nk2: v2")
def test_long_regex_open_pattern_streams_byte_by_byte(self):
"""Regression: a regex `open_pattern` whose full match spans well past the
old fixed 64-byte hold window (gpt-oss tool calls) must not be dropped when
the stream arrives in tiny chunks. Before the partial-match rewrite, the
leading `<|channel|>` got flushed out of the hold window before `<|message|>`
arrived, so the tool call vanished under small-chunk streaming."""
text = (
"<|channel|>analysis<|message|>Let me check.<|end|>"
"<|start|>assistant<|channel|>commentary to=functions.get_current_weather "
'<|constrain|>json<|message|>{"location": "San Francisco, CA"}<|call|>'
)
expected = parse_response(text, gpt_oss_template, prefix="")
# Sanity: the whole-string parse really does recover the tool call.
self.assertEqual(len(expected["tool_calls"]), 1)
self.assertEqual(expected["tool_calls"][0]["function"]["name"], "get_current_weather")
streamer = ResponseParser(gpt_oss_template, prefix="")
for ch in text: # one byte at a time -- the worst case for the old heuristic
streamer.feed(ch)
message, _ = streamer.finalize()
self.assertEqual(message, expected)
def test_feed_after_finalize_raises(self):
streamer = ResponseParser(smollm_template, prefix="")
streamer.feed("<think>x</think>")
streamer.finalize()
with self.assertRaises(RuntimeError):
streamer.feed("more")
with self.assertRaises(RuntimeError):
streamer.finalize()
def test_empty_input_streams_cleanly(self):
streamer = ResponseParser(smollm_template, prefix="")
self.assertEqual(streamer.feed(""), [])
result, final_events = streamer.finalize()
# Only the default fields should remain; nothing else is required.
self.assertEqual(result, {"role": "assistant"})
self.assertEqual(final_events, [])
class PrefixAndTruncationTest(unittest.TestCase):
def test_prefix_lands_inside_explicit_region(self):
"""A Qwen-style template emits `<|im_start|>assistant\\n<think>\\n` as the
assistant prefix. The model continues from inside the thinking block."""
prompt = (
"<|im_start|>system\nYou are helpful<|im_end|>\n"
"<|im_start|>user\nHi<|im_end|>\n"
"<|im_start|>assistant\n<think>\n"
)
generated = "Let me think...</think>"
stream = ResponseParser(qwen3_template, prefix=prompt)
# The region_open for `thinking` surfaces via initial_events; the
# caller replays it before feeding model output.
self.assertEqual(
[(e["type"], e["field"]) for e in stream.initial_events],
[("region_open", "thinking"), ("region_chunk", "thinking")],
)
events = stream.feed(generated)
result, _ = stream.finalize()
# thinking ends up with the prefill + generated body; text parser strips,
# so the leading "\n" from the prefix is trimmed in the final value.
self.assertEqual(result, {"role": "assistant", "thinking": "Let me think..."})
# The feed stream only sees the rest of the body and the close; the
# prefill already emitted region_open.
self.assertEqual([e["type"] for e in events], ["region_chunk", "region_close"])
self.assertEqual(events[1]["field"], "thinking")
def test_prefix_truncated_to_last_anchor(self):
"""Multiple `<|im_start|>assistant\\n` anchors in the prefix (multi-turn
conversation): only the slice after the LAST anchor matters."""
prompt = (
"<|im_start|>system\nA<|im_end|>\n"
"<|im_start|>user\nB<|im_end|>\n"
"<|im_start|>assistant\nEarlier reply<|im_end|>\n"
"<|im_start|>user\nFollowup<|im_end|>\n"
"<|im_start|>assistant\n<think>\n"
)
stream = ResponseParser(qwen3_template, prefix=prompt)
# We landed inside `thinking` (from the LAST assistant turn's `<think>\n`),
# not in some earlier-turn artifact.
opens = [e for e in stream.initial_events if e["type"] == "region_open"]
self.assertEqual([e["field"] for e in opens], ["thinking"])
# No earlier-turn content leaked into output.
stream.feed("done</think>")
stream.finalize()
self.assertEqual(stream._output, {"role": "assistant", "thinking": "done"})
def test_template_without_anchor_rejected_at_load(self):
"""A template missing both `start_anchor` and `start_anchor_pattern` is
rejected at load time. Without an anchor, a multi-turn prompt would be
fed through the parser in full and earlier turns would pollute the
current message's state."""
anchorless = {k: v for k, v in qwen3_template.items() if k != "start_anchor"}
with self.assertRaises(ValueError) as cm:
ResponseParser(anchorless)
msg = str(cm.exception)
self.assertIn("start_anchor", msg)
def test_prefix_anchor_not_found_falls_back(self):
"""Spec has start_anchor but the prefix doesn't contain it: parser
falls back to processing the entire prefix (with a logged warning)."""
prompt = "<think>\n" # no <|im_start|>assistant\n
stream = ResponseParser(qwen3_template, prefix=prompt)
opens = [e for e in stream.initial_events if e["type"] == "region_open"]
self.assertEqual([e["field"] for e in opens], ["thinking"])
stream.feed("hi</think>")
stream.finalize()
self.assertEqual(stream._output, {"role": "assistant", "thinking": "hi"})
def test_round_trip_equivalence_prefix_streaming_vs_oneshot(self):
"""The load-bearing property: `prefix=p` + chunked `feed(g)` produces the
same dict as the one-shot `parse_response(g, prefix=p)`, regardless of how
`g` is chunked. (Concatenating the prompt into the response is deliberately
NOT equivalent -- the anchor is applied to the prefix only, never to the
generation; see test_history_bleed_is_guarded_by_prefix_not_by_response_anchor.)"""
prompt = "<|im_start|>system\nA<|im_end|>\n<|im_start|>user\nB<|im_end|>\n<|im_start|>assistant\n<think>\n"
for name, tmpl_dict, gen_text in _STREAMING_FIXTURES:
if "thinking" not in gen_text and "<think>" not in gen_text:
continue
# Only fixtures whose generation text is compatible with starting
# inside `thinking`. Restrict to qwen3 / smollm shape for clarity.
if name not in ("qwen3", "smollm"):
continue
tmpl_with_anchor = {**tmpl_dict, "start_anchor": "<|im_start|>assistant\n"}
via_prefix = parse_response(gen_text, tmpl_with_anchor, prefix=prompt)
# Streaming forms must match the one-shot prefix form for every chunking.
for step in (1, 3, 7, 31):
with self.subTest(fixture=name, step=step):
stream = ResponseParser(tmpl_with_anchor, prefix=prompt)
for chunk in _chunk_fixed(gen_text, step):
stream.feed(chunk)
message, _ = stream.finalize()
self.assertEqual(message, via_prefix)
def test_history_bleed_is_guarded_by_prefix_not_by_response_anchor(self):
"""The `start_anchor` guards against history bleed only via `prefix=`; it is NOT
applied to the response. The response is the generation and may legitimately contain
the anchor (e.g. gpt-oss harmony opens every channel with `<|start|>assistant`), so
truncating it would drop real content. Passing the prompt as `prefix=` is the way to
keep earlier turns out of the parse."""
spec = {
"defaults": {"role": "assistant"},
"start_anchor": "<|im_start|>assistant\n",
"fields": {"content": {"close_pattern": r"\Z", "content": "text"}},
}
prompt = "<|im_start|>user\nHi<|im_end|>\n<|im_start|>assistant\n"
gen = "Hello there!"
clean = {"role": "assistant", "content": "Hello there!"}
# The supported guard: pass the prompt as prefix= so history is truncated off the prefix.
self.assertEqual(parse_response(gen, spec, prefix=prompt), clean)
# Pure generation parses cleanly with the explicit no-prefix opt-out (prefix="").
self.assertEqual(parse_response(gen, spec, prefix=""), clean)
# An anchor inside the response is treated as content, never as a history boundary:
# gpt-oss re-emits `<|start|>assistant` between channels, and that content survives.
gpt_oss_gen = (
"<|channel|>analysis<|message|>thinking<|end|><|start|>assistant<|channel|>final<|message|>answer"
)
self.assertEqual(
parse_response(gpt_oss_gen, gpt_oss_template, prefix=""),
{"role": "assistant", "thinking": "thinking", "content": "answer"},
)
def test_prefix_with_open_close_inside_truncated_region(self):
"""Prefix opens AND closes a region. The full open/chunk/close event
sequence is surfaced via initial_events, and the closed region lands
in the output dict — so renderers can show prefill content."""
spec = {
"defaults": {"role": "assistant"},
"start_anchor": "[BEGIN]",
"fields": {
"tag": {"open": "<tag>", "close": "</tag>", "content": "text"},
"body": {"close_pattern": r"$", "content": "text"}, # implicit
},
}
prefix = "noise[BEGIN]<tag>silently consumed</tag>"
stream = ResponseParser(spec, prefix=prefix)
types = [e["type"] for e in stream.initial_events]
self.assertEqual(types, ["region_open", "region_chunk", "region_close"])
self.assertTrue(all(e["field"] == "tag" for e in stream.initial_events))
self.assertEqual(stream.initial_events[-1]["value"], "silently consumed")
stream.feed("real generated body")
result, _ = stream.finalize()
self.assertEqual(result["tag"], "silently consumed")
self.assertEqual(result["body"], "real generated body")
def test_prefix_lands_inside_implicit_region(self):
"""Prefix wrote plaintext into the implicit region (e.g. assistant
prefill before the model continues). The region_open for the implicit
region must surface via initial_events so consumers don't miss it —
`_opened` will already be True by the time feed runs."""
prompt = "<|im_start|>assistant\nSure, here is "
stream = ResponseParser(smollm_template, prefix=prompt)
opens = [e for e in stream.initial_events if e["type"] == "region_open"]
self.assertEqual([e["field"] for e in opens], ["content"])
events = stream.feed("the answer<|im_end|>")
# No second region_open from feed — the implicit region was already
# opened during prefill and surfaced via initial_events.
self.assertNotIn("region_open", [e["type"] for e in events])
def test_prefix_partial_pattern_at_boundary(self):
"""Post-truncation prefix ends mid-delimiter. The first feed completes
the match; initial_events is empty (no region opened within the
prefix yet) and the open fires from `feed()`."""
prefix = "<|im_start|>assistant\n<thi" # incomplete `<think>`
stream = ResponseParser(qwen3_template, prefix=prefix)
self.assertEqual(stream.initial_events, [])
events = stream.feed("nk>real body</think>")
types = [e["type"] for e in events]
self.assertIn("region_open", types) # think opens during feed, not prefill
stream.finalize()
self.assertEqual(stream._output, {"role": "assistant", "thinking": "real body"})
def test_prefix_token_ids_decoded(self):
"""The tokenizer-level helper accepts token IDs as prefix (decoded
internally), matching how `response` is handled."""
tokenizer = AutoTokenizer.from_pretrained("openai-community/gpt2")
tokenizer.response_template = qwen3_template
prefix_text = "<|im_start|>assistant\n<think>\n"
prefix_ids = tokenizer(prefix_text).input_ids
from_str = tokenizer.parse_response("hi</think>", prefix=prefix_text)
from_ids = tokenizer.parse_response("hi</think>", prefix=prefix_ids)
self.assertEqual(from_str, from_ids)
def test_batched_parse_response_with_prefix(self):
"""Batched `parse_response`: a single prefix is broadcast to every item, a per-item prefix
list is matched positionally, and a prefix count that doesn't match the batch raises."""
tokenizer = AutoTokenizer.from_pretrained("openai-community/gpt2")
tokenizer.response_template = qwen3_template
prefix = "<|im_start|>assistant\n<think>\n"
gen_a, gen_b = "thinking A</think>answer A", "thinking B</think>answer B"
single_a = tokenizer.parse_response(gen_a, prefix=prefix)
single_b = tokenizer.parse_response(gen_b, prefix=prefix)
self.assertNotEqual(single_a, single_b)
# A single prefix is broadcast across the whole batch.
self.assertEqual(tokenizer.parse_response([gen_a, gen_b], prefix=prefix), [single_a, single_b])
# One prefix per item (here identical) is matched up positionally.
self.assertEqual(tokenizer.parse_response([gen_a, gen_b], prefix=[prefix, prefix]), [single_a, single_b])
# A prefix batch whose length doesn't match the responses is an error.
with self.assertRaises(ValueError):
tokenizer.parse_response([gen_a, gen_b], prefix=[prefix])
def test_tokenizer_get_response_parser_with_prefix(self):
"""`tokenizer.get_response_parser(prefix=...)` returns a stream that
is already in the right initial state."""
tokenizer = AutoTokenizer.from_pretrained("hf-internal-testing/tiny-random-gpt2")
tokenizer.response_template = qwen3_template
prefix = "<|im_start|>assistant\n<think>\n"
stream = tokenizer.get_response_parser(prefix=prefix)
opens = [e for e in stream.initial_events if e["type"] == "region_open"]
self.assertEqual([e["field"] for e in opens], ["thinking"])
stream.feed("body</think>")
result, _ = stream.finalize()
self.assertEqual(result, {"role": "assistant", "thinking": "body"})
if __name__ == "__main__":
unittest.main()