Ensure numpy hash uses tobytes and add test

Co-authored-by: mvdoc <[email protected]>

Author: Copilot

cortex/dataset/braindata.py

@@ -628,6 +628,7 @@ def __getitem__(self, masktype):
 
 def _hash(array):
     '''A simple numpy hash function'''
+    array = np.asarray(array)
     return hashlib.sha1(array.tobytes()).hexdigest()
 
 def _hdf_write(h5, data, name="data", group="/data"):

cortex/tests/test_braindata_hash_function.py

@@ -0,0 +1,11 @@
+import hashlib
+
+import numpy as np
+
+from cortex.dataset.braindata import _hash
+
+
+def test_hash_uses_tobytes():
+    array = np.arange(12, dtype=np.float32).reshape(3, 4)
+    expected = hashlib.sha1(array.tobytes()).hexdigest()
+    assert _hash(array) == expected