Allow file mode="x" with get_fs_token_paths (#1333)

* Also expand paths in exclusive file creation mode=x

* Add test for filepath expandsion with file mode=x

fsspec/core.py

@@ -635,6 +635,8 @@ def get_fs_token_paths(
     else:
         if "w" in mode and expand:
             paths = _expand_paths(paths, name_function, num)
+        elif "x" in mode and expand:
+            paths = _expand_paths(paths, name_function, num)
         elif "*" in paths:
             paths = [f for f in sorted(fs.glob(paths)) if not fs.isdir(f)]
         else:

fsspec/tests/test_core.py

@@ -13,6 +13,7 @@
     _expand_paths,
     expand_paths_if_needed,
     get_compression,
+    get_fs_token_paths,
     open_files,
     open_local,
 )
@@ -75,6 +76,11 @@ def test_expand_error():
         _expand_paths("*.*", None, 1)
 
 
+@pytest.mark.parametrize("mode", ["w", "w+", "x", "x+"])
+def test_expand_fs_token_paths(mode):
+    assert len(get_fs_token_paths("path", mode, num=2, expand=True)[-1]) == 2
+
+
 def test_openfile_api(m):
     m.open("somepath", "wb").write(b"data")
     of = OpenFile(m, "somepath")