Improve error message on inexistent files with local server (#754)

Add a check that the file exists when calling the (no-op)
`upload_file` method on the local file transfer strategy.

This ensures a nice error is produced when trying to import an
inexistent ACPH5 file, instead of failing on H5Open.

Resolves #748.

src/ansys/acp/core/_server/acp_instance.py

@@ -58,6 +58,8 @@ def __init__(self, working_directory: _PATH) -> None:
         self._working_directory = pathlib.Path(working_directory)
 
     def upload_file(self, local_path: _PATH) -> pathlib.Path:
+        if not pathlib.Path(local_path).exists():
+            raise FileNotFoundError(f"No such file or directory: '{local_path}'")
         return self._get_remote_path(local_path)
 
     def download_file(self, remote_path: _PATH, local_path: _PATH) -> None:

tests/unittests/test_acp_instance.py

@@ -75,3 +75,14 @@ def test_import_from_differenct_cwd(acp_instance, model_data_dir):
             assert (tmp_dir_path / export_filename).exists()
         # Check that the exported file does not exist on the original CWD
         assert not pathlib.Path(export_filename).exists()
+
+
+def test_import_inexistent(acp_instance):
+    """Test that inexistent files raise a FileNotFoundError.
+
+    Regression test for #748 (when run with 'direct' launch mode).
+    """
+    filename = "inexistent_file.acph5"
+    with pytest.raises(FileNotFoundError) as exc:
+        acp_instance.import_model(filename)
+    assert filename in str(exc.value)