raise exception if projection info is missing

mllam_data_prep/ops/projection.py

@@ -191,14 +191,14 @@ def validate_projection_consistency(
     >>> validate_projection_consistency([proj2, proj4])
     Traceback (most recent call last):
         ...
-    ValueError: Multiple projections found in the dataset.Currently only one projection is supported.
+    NotImplementedError: Multiple projections found in the dataset. Currently only one projection is supported.
     """
     proj_obs = [pyproj.CRS.from_cf(proj) for proj in projections]
 
     # Check that all projections are the same
     if len(set(proj_obs)) > 1:
-        raise ValueError(
-            "Multiple projections found in the dataset."
+        raise NotImplementedError(
+            "Multiple projections found in the dataset. "
             "Currently only one projection is supported."
         )
 
@@ -256,7 +256,7 @@ def get_projection_crs(ds: xr.Dataset) -> Dict[str, Any]:
     vars_wo_proj = set(ds.data_vars) - set(vars_w_proj.keys()) - proj_vars
 
     if len(proj_vars) > 1:
-        raise ValueError(
+        raise NotImplementedError(
             f"Multiple referenced projections found in the dataset {ds.encoding.get('source',None)}: {proj_vars}. "
             "Currently only one projection is supported."
         )

tests/test_from_config.py

@@ -346,6 +346,28 @@ def test_projection_from_config(projection: Dict):
         ), "CRS mismatch"
 
 
+@pytest.mark.parametrize(
+    "projection",
+    [
+        {"proj2": {"dims": "[x y]", "crs_wkt": "EPSG:4326"}},
+    ],
+)
+def test_requirement_of_single_projection(projection: Dict):
+    """
+    Test that assertion is raised when projections
+    are missing from input datasets.
+    """
+    # Adding projection config to the example config
+    config = yaml.safe_load(testconfig.VALID_EXAMPLE_CONFIG_YAML)
+    config["inputs"]["danra_surface"]["projections"] = projection
+    config_yaml = yaml.dump(config)
+
+    config = mdp.Config.from_yaml(config_yaml)
+
+    with pytest.raises(NotImplementedError):
+        mdp.create_dataset(config=config)
+
+
 def test_danra_example():
     fp_config = Path(__file__).parent.parent / "example.danra.yaml"
     with tempfile.TemporaryDirectory(suffix=".zarr") as tmpdir: