Ability to generate planar metric terms and addition of test_eta.py unit test

.github/workflows/unit_tests.yaml

@@ -22,6 +22,10 @@ jobs:
         - name: Install Python packages
           run: pip3 install .[test]
 
+        - name: prepare input eta files
+          run: |
+            python tests/grid/generate_eta_files.py
+
         - name: Run serial-cpu tests
           run: coverage run --rcfile=setup.cfg -m pytest -x tests
 

ndsl/grid/eta.py

@@ -30,10 +30,8 @@ class HybridPressureCoefficients:
 
 
 def _load_ak_bk_from_file(eta_file: str) -> Tuple[np.ndarray, np.ndarray]:
-    if eta_file == "None":
-        raise ValueError("eta file not specified")
     if not os.path.isfile(eta_file):
-        raise ValueError("file " + eta_file + " does not exist")
+        raise ValueError(f"eta file {eta_file} does not exist")
 
     # read file into ak, bk arrays
     data = xr.open_dataset(eta_file)

ndsl/grid/generation.py

@@ -237,7 +237,7 @@ def __init__(
         dy_const: float = 1000.0,
         deglat: float = 15.0,
         extdgrid: bool = False,
-        eta_file: str = "None",
+        eta_file: Optional[str] = None,
         ak: Optional[np.ndarray] = None,
         bk: Optional[np.ndarray] = None,
     ):
@@ -297,12 +297,34 @@ def __init__(
         self._dy_center = None
         self._area = None
         self._area_c = None
-        (
-            self._ks,
-            self._ptop,
-            self._ak,
-            self._bk,
-        ) = self._set_hybrid_pressure_coefficients(eta_file, ak, bk)
+        if eta_file is not None:
+            (
+                self._ks,
+                self._ptop,
+                self._ak,
+                self._bk,
+            ) = self._set_hybrid_pressure_coefficients(eta_file, ak, bk)
+        else:
+            self._ks = self.quantity_factory.zeros(
+                [],
+                "",
+                dtype=Float,
+            )
+            self._ptop = self.quantity_factory.zeros(
+                [],
+                "Pa",
+                dtype=Float,
+            )
+            self._ak = self.quantity_factory.zeros(
+                [Z_INTERFACE_DIM],
+                "Pa",
+                dtype=Float,
+            )
+            self._bk = self.quantity_factory.zeros(
+                [Z_INTERFACE_DIM],
+                "",
+                dtype=Float,
+            )
         self._ec1 = None
         self._ec2 = None
         self._ew1 = None