Add a step for writing reconstruction coefficients

The coefficients are used to construct 3D Cartesian as well as
zonal and meridional components of a field at cell centers from
the normal component of the field at edges.

compass/ocean/tests/global_ocean/files_for_e3sm/__init__.py

@@ -38,6 +38,9 @@
 from compass.ocean.tests.global_ocean.files_for_e3sm.seaice_mesh import (  # noqa: E501
     SeaiceMesh,
 )
+from compass.ocean.tests.global_ocean.files_for_e3sm.write_coeffs_reconstruct import (  # noqa: E501
+    WriteCoeffsReconstruct,
+)
 from compass.ocean.tests.global_ocean.forward import get_forward_subdir
 from compass.testcase import TestCase
 
@@ -115,6 +118,10 @@ def __init__(self, test_group, mesh=None, init=None,
         self.add_step(RemapIcebergClimatology(
             test_case=self))
 
+        if mesh is not None and init is not None:
+            self.add_step(WriteCoeffsReconstruct(
+                test_case=self, mesh=mesh, init=init))
+
     def configure(self):
         """
         Modify the configuration options for this test case

compass/ocean/tests/global_ocean/files_for_e3sm/write_coeffs_reconstruct/__init__.py

@@ -0,0 +1,56 @@
+import os
+
+from compass.io import symlink
+from compass.ocean.tests.global_ocean.files_for_e3sm.files_for_e3sm_step import (  # noqa: E501
+    FilesForE3SMStep,
+)
+from compass.ocean.tests.global_ocean.forward import ForwardStep
+
+
+class WriteCoeffsReconstruct(ForwardStep, FilesForE3SMStep):
+    """
+    A step for writing out ``coeffs_reconstruct`` for a given MPAS mesh
+    """
+
+    def __init__(self, test_case, mesh, init):
+        """
+        Create a new step
+
+        Parameters
+        ----------
+        test_case : compass.TestCase
+            The test case this step belongs to
+
+        mesh : compass.ocean.tests.global_ocean.mesh.Mesh
+            The test case that produces the mesh for this run
+
+        init : compass.ocean.tests.global_ocean.init.Init
+            The test case that produces the initial condition for this run
+        """
+        super().__init__(test_case=test_case, mesh=mesh, init=init,
+                         time_integrator='split_explicit',
+                         name='write_coeffs_reconstruct')
+
+        package = 'compass.ocean.tests.global_ocean.files_for_e3sm.' \
+                  'write_coeffs_reconstruct'
+
+        self.add_namelist_file(package, 'namelist.reconstruct')
+        self.add_streams_file(package, 'streams.reconstruct')
+
+    def run(self):
+        """
+        Run this step of the testcase
+        """
+        super().run()
+
+        reconstruct_dir = \
+            '../assembled_files/diagnostics/mpas_analysis/reconstruct'
+        try:
+            os.makedirs(reconstruct_dir)
+        except FileExistsError:
+            pass
+
+        reconstruct_filename = f'{self.mesh_short_name}_coeffs_reconstruct.nc'
+        # make links in diagnostics directory
+        symlink(os.path.abspath('coeffs_reconstruct.nc'),
+                f'{reconstruct_dir}/{reconstruct_filename}')

compass/ocean/tests/global_ocean/files_for_e3sm/write_coeffs_reconstruct/namelist.reconstruct

@@ -0,0 +1 @@
+config_run_duration = '0000_00:00:01'

compass/ocean/tests/global_ocean/files_for_e3sm/write_coeffs_reconstruct/streams.reconstruct

@@ -0,0 +1,13 @@
+<streams>
+
+<stream name="coeffs_reconstruct"
+        type="output"
+        filename_template="coeffs_reconstruct.nc"
+        output_interval="0000_00:00:01"
+		reference_time="0001-01-01_00:00:00"
+        clobber_mode="truncate">
+
+    <var name="coeffs_reconstruct"/>
+</stream>
+
+</streams>