test_identities: Run on sphere.

test/test_layer_pot.py

@@ -751,6 +751,9 @@ def test_identities(ctx_getter, zero_op_name, mesh_name, mesh_getter, qbx_order,
     if mesh_name == "sphere" and k != 0:
         pytest.skip("both direct eval and generating the FMM kernels are too slow")
 
+    if mesh_name == "sphere" and zero_op_name == "green_grad":
+        pytest.skip("does not achieve sufficient precision")
+
     target_order = 8
 
     order_table = {
@@ -813,11 +816,8 @@ def test_identities(ctx_getter, zero_op_name, mesh_name, mesh_getter, qbx_order,
 
         if d == 2:
             order_bump = 15
-            direct_eval = False
         elif d == 3:
             order_bump = 8
-            # FIXME: FMM kernel generation slow
-            direct_eval = (k != 0)
 
         refiner_extra_kwargs = {}