macOS is not case-sensitive by default

exdir/core/validation.py

@@ -1,7 +1,7 @@
 from enum import Enum
 import os
 import sys
-from pathlib import Path, WindowsPath
+from tempfile import NamedTemporaryFile
 from unicodedata import category
 from . import constants as exob
 
@@ -118,7 +118,8 @@ def thorough(parent_path, name):
     name_lower = name_str.lower()
     _assert_valid_characters(name_lower)
 
-    if isinstance(Path(parent_path), WindowsPath):
+    # TODO investigate replacing with sys.platform
+    if not _is_fs_case_sensitive(parent_path):
         # use _assert_unique if we're already on Windows, because it is much faster
         # than the test below
         _assert_unique(parent_path, name)
@@ -135,3 +136,13 @@ def thorough(parent_path, name):
 
 def none(parent_path, name):
     pass
+
+
+def _is_fs_case_sensitive(source_dir=None):
+    # Adapted from https://stackoverflow.com/a/36580834/
+    if not hasattr(_is_fs_case_sensitive, "case_sensitive"):
+        with NamedTemporaryFile(prefix="TmP", dir=source_dir) as tmp_file:
+            setattr(_is_fs_case_sensitive,
+                    "case_sensitive",
+                    not os.path.exists(tmp_file.name.lower()))
+    return _is_fs_case_sensitive.case_sensitive