Update tests and docs

docs/src/getting-started/usage.rst

@@ -58,15 +58,31 @@ the current directory and type
 Evaluation
 ##########
 
-The sub-command to evaluate a already trained model is
+The sub-command to evaluate an already trained model is
 
 .. code-block:: bash
 
     metatensor-models eval
 
 .. literalinclude:: ../../../examples/usage.sh
     :language: bash
-    :lines: 9-
+    :lines: 9-25
+
+
+Exporting
+#########
+
+Exporting a model is very useful if you want to use it in other frameworks,
+especially in molecular dynamics simulations.
+The sub-command to export an already trained model is
+
+.. code-block:: bash
+
+    metatensor-models export
+
+.. literalinclude:: ../../../examples/usage.sh
+    :language: bash
+    :lines: 25-
 
 In the next tutorials we show how adjust the dataset section of ``options.yaml`` file
 to use it for your own datasets.

examples/usage.sh

@@ -22,3 +22,9 @@ head -n 20 output.xyz
 # All command line flags of the eval sub-command can be listed via
 
 metatensor-models eval --help
+
+# For example, the following command
+
+metatensor-models export model.pt
+
+# creates an `exported-model.pt` file that contains the exported model.

src/metatensor/models/cli/export_model.py

@@ -47,4 +47,7 @@ def export_model(model: str, output: Optional[str]) -> None:
 
     # Export the model
     wrapper = MetatensorAtomisticModel(loaded_model.eval(), loaded_model.capabilities)
-    wrapper.export("exported-model.pt")
+    if output is None:
+        wrapper.export("exported-model.pt")
+    else:
+        wrapper.export(output)

tests/cli/test_export_model.py

@@ -0,0 +1,32 @@
+import os
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+
+# Execute the setup script which will make sum_over_samples saveable.
+current_dir = os.path.dirname(__file__)
+setup_path = os.path.join(current_dir, "..", "..", "scripts", "setup.py")
+exec(open(setup_path).read())
+
+
+RESOURCES_PATH = Path(__file__).parent.resolve() / ".." / "resources"
+
+
+@pytest.mark.parametrize("output", [None, "exported.pt"])
+def test_export(monkeypatch, tmp_path, output):
+    """Test that the export cli runs without an error raise."""
+    monkeypatch.chdir(tmp_path)
+    shutil.copy(RESOURCES_PATH / "bpnn-model.pt", "bpnn-model.pt")
+
+    command = ["metatensor-models", "export", "bpnn-model.pt"]
+
+    if output is not None:
+        command += ["-o", output]
+    else:
+        output = "exported-model.pt"
+
+    subprocess.check_call(command)
+    assert Path(output).is_file()