test: reject WSL bash, accept only MSYS/MINGW on Windows

On Windows, verify uname -s reports MSYS, MINGW, or CYGWIN so the WSL
launcher (System32\bash.exe) is rejected — it cannot handle native
Windows paths used by test fixtures. Add SPECKIT_TEST_BASH=1 env var
escape hatch to force-enable bash tests in non-standard setups.

Author: mnriem

tests/conftest.py

@@ -1,26 +1,53 @@
 """Shared test helpers for the Spec Kit test suite."""
 
+import os
 import re
 import shutil
 import subprocess
+import sys
 
 import pytest
 
 _ANSI_ESCAPE_RE = re.compile(r"\x1b\[[0-?]*[ -/]*[@-~]")
 
 
 def _has_working_bash() -> bool:
-    """Check whether a functional bash is available (not just a WSL stub)."""
+    """Check whether a functional native bash is available.
+
+    On Windows, only Git-for-Windows bash (MSYS2/MINGW) is accepted.
+    The WSL launcher (System32\\bash.exe) is rejected because it runs in
+    a separate Linux filesystem and cannot handle native Windows paths
+    used by the test fixtures.
+
+    Set SPECKIT_TEST_BASH=1 to force-enable bash tests regardless.
+    """
+    if os.environ.get("SPECKIT_TEST_BASH") == "1":
+        return True
     if shutil.which("bash") is None:
         return False
     try:
         r = subprocess.run(
             ["bash", "-c", "echo ok"],
             capture_output=True, text=True, timeout=5,
         )
-        return r.returncode == 0 and "ok" in r.stdout
+        if r.returncode != 0 or "ok" not in r.stdout:
+            return False
     except (OSError, subprocess.TimeoutExpired):
         return False
+    # On Windows, verify we have MSYS/MINGW bash (Git for Windows),
+    # not the WSL launcher which can't handle native paths.
+    if sys.platform == "win32":
+        try:
+            u = subprocess.run(
+                ["bash", "-c", "uname -s"],
+                capture_output=True, text=True, timeout=5,
+            )
+            kernel = u.stdout.strip().upper()
+            if not any(k in kernel for k in ("MSYS", "MINGW", "CYGWIN")):
+                return False
+        except (OSError, subprocess.TimeoutExpired):
+            return False
+    return True
 
 
 requires_bash = pytest.mark.skipif(