diff --git a/pybamm/models/submodels/particle/fast/base_fast_particle.py b/pybamm/models/submodels/particle/fast/base_fast_particle.py
index f45885cd2f..a39e00b519 100644
--- a/pybamm/models/submodels/particle/fast/base_fast_particle.py
+++ b/pybamm/models/submodels/particle/fast/base_fast_particle.py
@@ -2,7 +2,6 @@
 # Base class for particles each with uniform concentration (i.e. infinitely fast
 # diffusion in r)
 #
-import pybamm
 from ..base_particle import BaseParticle
 
 
diff --git a/tests/unit/test_models/test_submodels/test_particle/test_base_particle.py b/tests/unit/test_models/test_submodels/test_particle/test_base_particle.py
index 8cc958d1d2..084bc3b621 100644
--- a/tests/unit/test_models/test_submodels/test_particle/test_base_particle.py
+++ b/tests/unit/test_models/test_submodels/test_particle/test_base_particle.py
@@ -9,15 +9,17 @@
 
 class TestBaseParticle(unittest.TestCase):
     def test_public_functions(self):
+        variables = {
+            "Negative particle surface concentration": 0,
+            "Positive particle surface concentration": 0,
+        }
         submodel = pybamm.particle.BaseParticle(None, "Negative")
-        std_tests = tests.StandardSubModelTests(submodel)
-        with self.assertRaises(NotImplementedError):
-            std_tests.test_all()
+        std_tests = tests.StandardSubModelTests(submodel, variables)
+        std_tests.test_all()
 
         submodel = pybamm.particle.BaseParticle(None, "Positive")
-        std_tests = tests.StandardSubModelTests(submodel)
-        with self.assertRaises(NotImplementedError):
-            std_tests.test_all()
+        std_tests = tests.StandardSubModelTests(submodel, variables)
+        std_tests.test_all()
 
 
 if __name__ == "__main__":