Allow loading npz files which use DEFLATE compression

This does not change file saving, we are still only using STORED
in this case

metatensor-core/Cargo.toml

@@ -24,7 +24,7 @@ smallvec = {version = "1", features = ["union"]}
 # implementation of the NPZ serialization format
 byteorder = {version = "1"}
 num-traits = {version = "0.2", default-features = false}
-zip = {version = "0.6", default-features = false}
+zip = {version = "0.6", default-features = false, features = ["deflate"]}
 
 [build-dependencies]
 cbindgen = { version = "0.26", default-features = false }

python/metatensor-core/tests/serialization.py

@@ -80,6 +80,30 @@ def test_load(use_numpy, memory_buffer, standalone_fn):
  assert gradient.values.shape == (59, 3, 5, 3)
 
 
+@pytest.mark.parametrize("use_numpy", (True, False))
+def test_load_deflate(use_numpy):
+ # This file was saved using DEFLATE to compress the different ZIP archive members
+ path = os.path.join(
+ os.path.dirname(__file__),
+ "..",
+ "..",
+ "metatensor-operations",
+ "tests",
+ "data",
+ "qm7-power-spectrum.npz",
+ )
+
+ tensor = metatensor.load(path, use_numpy=use_numpy)
+
+ assert isinstance(tensor, TensorMap)
+ assert tensor.keys.names == [
+ "center_type",
+ "neighbor_1_type",
+ "neighbor_2_type",
+ ]
+ assert len(tensor.keys) == 17
+
+
 # using tmpdir as pytest-built-in fixture
 # https://docs.pytest.org/en/7.1.x/how-to/tmp_path.html#the-tmpdir-and-tmpdir-factory-fixtures
 @pytest.mark.parametrize("use_numpy", (True, False))