#1477 increase coverage

pybamm/solvers/idaklu_solver.py

@@ -53,7 +53,7 @@ def __init__(
         max_steps="deprecated",
     ):
 
-        if idaklu_spec is None:
+        if idaklu_spec is None:  # pragma: no cover
             raise ImportError("KLU is not installed")
 
         super().__init__(
@@ -140,7 +140,7 @@ def _check_atol_type(self, atol, size):
         if atol.size != size:
             raise pybamm.SolverError(
                 """Absolute tolerances must be either a scalar or a numpy arrray
-                of the same shape at y0"""
+                of the same shape as y0 ({})""".format(size)
             )
 
         return atol

tests/unit/test_solvers/test_idaklu_solver.py

@@ -130,6 +130,31 @@ def test_set_atol(self):
         variable_tols = {"Porosity times concentration": 1e-3}
         solver.set_atol_by_variable(variable_tols, model)
 
+        model = pybamm.BaseModel()
+        u = pybamm.Variable("u")
+        model.rhs = {u: -0.1 * u}
+        model.initial_conditions = {u: 1}
+        t_eval = np.linspace(0, 3, 100)
+
+        disc = pybamm.Discretisation()
+        disc.process_model(model)
+
+        # numpy array atol
+        atol = np.zeros(1)
+        solver = pybamm.IDAKLUSolver(root_method="lm", atol=atol)
+        solver.solve(model, t_eval)
+
+        # list atol
+        atol = [1]
+        solver = pybamm.IDAKLUSolver(root_method="lm", atol=atol)
+        solver.solve(model, t_eval)
+
+        # wrong size (should fail)
+        atol = [1, 2]
+        solver = pybamm.IDAKLUSolver(root_method="lm", atol=atol)
+        with self.assertRaisesRegex(pybamm.SolverError, 'Absolute tolerances'):
+            solver.solve(model, t_eval)
+
     def test_failures(self):
         # this test implements a python version of the ida Roberts
         # example provided in sundials
@@ -149,6 +174,23 @@ def test_failures(self):
         with self.assertRaisesRegex(pybamm.SolverError, "KLU requires the Jacobian"):
             solver.solve(model, t_eval)
 
+        model = pybamm.BaseModel()
+        u = pybamm.Variable("u")
+        model.rhs = {u: -0.1 * u}
+        model.initial_conditions = {u: 1}
+
+        disc = pybamm.Discretisation()
+        disc.process_model(model)
+
+        solver = pybamm.IDAKLUSolver(root_method="lm")
+
+        # will give solver error
+        t_eval = np.linspace(0, -3, 100)
+        with self.assertRaisesRegex(
+            pybamm.SolverError, 't_eval must increase monotonically'
+        ):
+            solver.solve(model, t_eval)
+
     def test_dae_solver_algebraic_model(self):
         model = pybamm.BaseModel()
         var = pybamm.Variable("var")