tests: Add apply test back

tests/test_petsc.py

@@ -482,31 +482,31 @@ def test_petsc_struct():
     assert all(not isinstance(i, CCompositeObject) for i in op.parameters)
 
 
-# @skipif('petsc')
-# @pytest.mark.parallel(mode=[2, 4, 8])
-# def test_apply(mode):
+@skipif('petsc')
+@pytest.mark.parallel(mode=[2, 4, 8])
+def test_apply(mode):
 
-#     grid = Grid(shape=(13, 13), dtype=np.float64)
+    grid = Grid(shape=(13, 13), dtype=np.float64)
 
-#     pn = Function(name='pn', grid=grid, space_order=2, dtype=np.float64)
-#     rhs = Function(name='rhs', grid=grid, space_order=2, dtype=np.float64)
-#     mu = Constant(name='mu', value=2.0)
+    pn = Function(name='pn', grid=grid, space_order=2, dtype=np.float64)
+    rhs = Function(name='rhs', grid=grid, space_order=2, dtype=np.float64)
+    mu = Constant(name='mu', value=2.0)
 
-#     eqn = Eq(pn.laplace*mu, rhs, subdomain=grid.interior)
+    eqn = Eq(pn.laplace*mu, rhs, subdomain=grid.interior)
 
-#     petsc = PETScSolve(eqn, pn)
+    petsc = PETScSolve(eqn, pn)
 
-#     # Build the op
-#     with switchconfig(openmp=False, mpi=True):
-#         op = Operator(petsc)
+    # Build the op
+    with switchconfig(openmp=False, mpi=True):
+        op = Operator(petsc)
 
-#     # Check the Operator runs without errors. Not verifying output for
-#     # now. Need to consolidate BC implementation
-#     op.apply()
+    # Check the Operator runs without errors. Not verifying output for
+    # now. Need to consolidate BC implementation
+    op.apply()
 
-#     # Verify that users can override `mu`
-#     mu_new = Constant(name='mu_new', value=4.0)
-#     op.apply(mu=mu_new)
+    # Verify that users can override `mu`
+    mu_new = Constant(name='mu_new', value=4.0)
+    op.apply(mu=mu_new)
 
 
 @skipif('petsc')