Adding simple test for particle start times that are not multiple of dt

tests/test_particle_sets.py

@@ -168,6 +168,19 @@ def test_pset_create_with_time(fieldset, pset_mode, mode, npart=100):
     assert np.allclose([p.time for p in pset], time, rtol=1e-12)
 
 
+@pytest.mark.parametrize('pset_mode', pset_modes)
+@pytest.mark.parametrize('mode', ['scipy', 'jit'])
+def test_pset_not_multipldt_time(fieldset, pset_mode, mode):
+    times = [0, 1.1]
+    pset = pset_type[pset_mode]['pset'](fieldset, lon=[0]*2, lat=[0]*2, pclass=ptype[mode], time=times)
+
+    def Addlon(particle, fieldset, time):
+        particle.lon += particle.dt
+
+    pset.execute(Addlon, dt=1, runtime=2)
+    assert np.allclose([p.lon for p in pset], [2 - t for t in times])
+
+
 @pytest.mark.parametrize('pset_mode', pset_modes)
 @pytest.mark.parametrize('mode', ['scipy', 'jit'])
 def test_pset_repeated_release(fieldset, pset_mode, mode, npart=10):