create a variable to hold output dimensions

test/test_flux_derivatives.py

@@ -48,6 +48,7 @@ class GridResults:
     ndim = 3
     nvars = 5
     dir_map = {"xi":1, "eta":2, "zeta":3}
+    output_dims = (nvars, nx, ny, nz)
 
     def __init__(self, dir_str):
         self.direction = self.dir_map[dir_str]
@@ -56,7 +57,7 @@ class GridResults:
         self.generalized_fluxes = np.full((self.nvars, self.nxhalo, self.nyhalo, self.nzhalo), 1.0, dtype=np.float64, order="F")
         self.metrics = np.full((self.ndim, self.ndim, self.nxhalo, self.nyhalo, self.nzhalo), 1.0, dtype=np.float64, order="F")
         self.jacobians = np.full((self.nxhalo, self.nyhalo, self.nzhalo), 1.0, dtype=np.float64, order="F")
-        self.generalized_flux_derivatives = np.full((self.nvars, self.nx, self.ny, self.nz), 0.0)
+        self.generalized_flux_derivatives = np.full(self.output_dims, 0.0)
 
 
 @pytest.fixture(scope="session", params=["xi", "eta", "zeta"])
@@ -70,7 +71,7 @@ def test_compute_flux_derivatives(queue, grid_results):
     prg = u.get_weno_program()
     prg = prg.copy(target=lp.PyOpenCLTarget(queue.device))
 
-    flux_derivatives_dev = u.empty_array_on_device(queue, data.nvars,data.nx,data.ny,data.nz)
+    flux_derivatives_dev = u.empty_array_on_device(queue, *data.output_dims)
 
     prg(queue,
             nvars=data.nvars,