[ci] add vllm_test_utils (#10659)

Signed-off-by: youkaichao <youkaichao@gmail.com>

tests/vllm_test_utils/setup.py

@@ -0,0 +1,7 @@
+from setuptools import setup
+
+setup(
+    name='vllm_test_utils',
+    version='0.1',
+    packages=['vllm_test_utils'],
+)

tests/vllm_test_utils/vllm_test_utils/__init__.py

@@ -0,0 +1,8 @@
+"""
+vllm_utils is a package for vLLM testing utilities.
+It does not import any vLLM modules.
+"""
+
+from .blame import BlameResult, blame
+
+__all__ = ["blame", "BlameResult"]

tests/vllm_test_utils/vllm_test_utils/blame.py

@@ -0,0 +1,53 @@
+import contextlib
+import dataclasses
+import sys
+import traceback
+from typing import Callable, Generator
+
+
+@dataclasses.dataclass
+class BlameResult:
+    found: bool = False
+    trace_stack: str = ""
+
+
+@contextlib.contextmanager
+def blame(func: Callable) -> Generator[BlameResult, None, None]:
+    """
+    Trace the function calls to find the first function that satisfies the
+    condition. The trace stack will be stored in the result.
+
+    Usage:
+
+    ```python
+    with blame(lambda: some_condition()) as result:
+        # do something
+    
+    if result.found:
+        print(result.trace_stack)
+    """
+    result = BlameResult()
+
+    def _trace_calls(frame, event, arg=None):
+        nonlocal result
+        if event in ['call', 'return']:
+            # for every function call or return
+            try:
+                # Temporarily disable the trace function
+                sys.settrace(None)
+                # check condition here
+                if not result.found and func():
+                    result.found = True
+                    result.trace_stack = "".join(traceback.format_stack())
+                # Re-enable the trace function
+                sys.settrace(_trace_calls)
+            except NameError:
+                # modules are deleted during shutdown
+                pass
+        return _trace_calls
+
+    sys.settrace(_trace_calls)
+
+    yield result
+
+    sys.settrace(None)