Skip clang-tidy if not available

test/test_linter.py

@@ -1,5 +1,7 @@
 import os
 from glob import glob
+import shutil
+import unittest
 
 import pqclean
 from helpers import run_subprocess
@@ -12,6 +14,8 @@ def test_clang_tidy():
 
 
 def check_tidy(implementation: pqclean.Implementation):
+    if shutil.which('clang-tidy') is None:
+        raise unittest.SkipTest("clang-tidy unavailable in PATH")
     cfiles = glob(os.path.join(implementation.path(), '*.c'))
     common_files = glob(os.path.join('..', 'common', '*.c'))
     run_subprocess(['clang-tidy',