introduce REQUIRE_SCANDIR_EXTENSION=1 envvar

.github/workflows/tests.yml

@@ -31,7 +31,7 @@ jobs:
           python -m pip install wheel
       - name: Install
         run: |
-          python -m pip install .
+          REQUIRE_SCANDIR_EXTENSION=1 python -m pip install .
       - name: Run tests
         run: |
           python test/run_tests.py

setup.py

@@ -17,6 +17,8 @@
 import sys
 import logging
 
+REQUIRE_EXTENSION = bool(os.environ.get("REQUIRE_SCANDIR_EXTENSION"))
+
 # Get version without importing scandir because that will lock the
 # .pyd file (if scandir is already installed) so it can't be
 # overwritten during the install process
@@ -42,6 +44,9 @@ def build_extension(self, ext):
         try:
             base_build_ext.build_extension(self, ext)
         except Exception:
+            if REQUIRE_EXTENSION:
+                logging.error('REQUIRE_SCANDIR_EXTENSION is set, not falling back to Python implementation')
+                raise
             info = sys.exc_info()
             logging.warn("building %s failed with %s: %s", ext.name, info[0], info[1])