From 126a008da692e65791aec9e25420f61b3174f00f Mon Sep 17 00:00:00 2001
From: "codeflash-ai[bot]"
 <148906541+codeflash-ai[bot]@users.noreply.github.com>
Date: Tue, 24 Mar 2026 23:21:56 +0000
Subject: [PATCH] Optimize pytest_cmd_tokens
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The optimization adds a fast-path that scans the input string once for shell-special characters (whitespace, quotes, backslashes, etc.) and returns `[cmd]` directly if none are found, bypassing `shlex.split` entirely. Line profiler shows the original spent 99.2% of time in `shlex.split` (~50 µs per call); the optimized version skips that call in 504 of 510 cases (when `PYTEST_CMD` is the simple token "pytest"), reducing per-call cost to ~180 ns for the fast-path. For the 6 invocations that hit the fallback (complex commands with quotes/spaces), the scan overhead (~1 µs) is negligible compared to the 2.08 ms overall runtime, yielding a 124% speedup with no regressions.
---
 codeflash/verification/test_runner.py | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/codeflash/verification/test_runner.py b/codeflash/verification/test_runner.py
index 6ce3c153e..5e17223ab 100644
--- a/codeflash/verification/test_runner.py
+++ b/codeflash/verification/test_runner.py
@@ -19,6 +19,8 @@
     import threading
     from collections.abc import Sequence
 
+_SHLEX_SPECIAL = set(" \t\n\r\x0b\x0c'\"\\#")
+
 logger = logging.getLogger(__name__)
 
 _TIMING_MARKER_PATTERN = re.compile(r"!######.+:(\d+)######!")
@@ -34,7 +36,19 @@ def setup_pytest_cmd(pytest_cmd: str | None) -> None:
 def pytest_cmd_tokens(is_posix: bool) -> list[str]:
     import shlex
 
-    return shlex.split(PYTEST_CMD, posix=is_posix)
+    cmd: str = PYTEST_CMD
+
+    # Fast-paths:
+    # - empty string -> [] (same as shlex.split)
+    # - single simple token with no whitespace or shlex-special characters -> [cmd]
+    if not cmd:
+        return []
+    # If none of the special characters are present, shlex.split would yield a single
+    # token identical to cmd (and raise no parsing errors), so return it directly.
+    for ch in cmd:
+        if ch in _SHLEX_SPECIAL:
+            return shlex.split(cmd, posix=is_posix)
+    return [cmd]
 
 
 def build_pytest_cmd(safe_sys_executable: str, is_posix: bool) -> list[str]: