Add a test to check that adding and removing an interaction both works and writes zeros to the data table

Author: rpep

tests/test_add_remove_interaction.py

@@ -0,0 +1,25 @@
+from fidimag.common import CuboidMesh, constant
+from fidimag.micro import UniformExchange, Sim, Zeeman
+import numpy as np
+
+def test_add_remove_interaction_simple():
+    mesh = CuboidMesh(nx=10, ny=10, nz=10, unit_length=1e-9)
+    name = 'test_add_remove_intn_simple'
+    sim = Sim(mesh, name=name)
+    sim.set_m(lambda pos: (0, 0, 1))
+    sim.set_Ms(5.8e5)
+    exch = UniformExchange(A=1e-11, name='Exchange')
+    zee = Zeeman((0, 0, 0.05 / constant.mu_0), name='Zeeman')
+    sim.add(exch)
+    sim.add(zee)
+    sim.driver.run_until(1e-9)
+    sim.remove('Zeeman')
+    sim.driver.run_until(2e-9)
+    f = open(name + '.txt')
+    lines = f.read().split('\n')
+    headers = lines[0].split()
+    first_data = lines[2].split()
+    last_data = lines[2].split()
+    # Find the position in the data table
+    position = headers.index('E_Zeeman')
+    assert np.abs(float(last_data[position])) < 1e-15