def test_potential_returns_float(self):
testObj = Charge(self.positionList, self.charge)
ppos = [1, 0, 0]
electric_potential = testObj.potential(ppos)
assert isinstance(electric_potential, float)
def test_field_returns_numpy_array(self):
testObj = Charge(self.positionList, self.charge)
fpos = [1, 0, 0]
electric_field = testObj.field(fpos)
assert isinstance(electric_field, np.ndarray)
def test_field_returns_expected_values(self):
testObj = Charge(self.positionList, -self.charge)
fpos = [1, 0, 0]
electric_field = testObj.field(fpos)
expected_field = np.array([-62.9, 0, 0])
np.testing.assert_allclose(electric_field, expected_field, atol=1e-1)
def test_field_from_potential_returns_near_analytical(self):
testObj = Charge(self.positionList, -self.charge)
fpos = [1, 0, 0]
electric_field = testObj.field(fpos, "potential")
expected_field = testObj.field(fpos, "analytical")
np.testing.assert_allclose(electric_field, expected_field, atol=1e-1)
def test_potential_returns_known_constant_case(self):
pos = [0, 0, 0]
charge = 1
testObj = Charge(pos, charge)
ppos = [1, 0, 0]
potential = testObj.potential(ppos)
expected_potential = (4 * pi * epsilon_0)**-1
np.testing.assert_equal(potential, expected_potential)
def test_field_returns_known_constant_case(self):
pos = [0, 0, 0]
charge = 1
testObj = Charge(pos, charge)
fpos = [1, 0, 0]
field = testObj.field(fpos)
field_constant = (4 * pi * epsilon_0)**-1
expected_field = np.array([field_constant, 0, 0])
np.testing.assert_equal(field, expected_field)
def test_potential_volume_at_point_equal_class_potential(self):
charge = Charge(self.position_1, self.charge)
potential_volume = volume.potential(
[charge],
x_range=[-10, 10],
y_range=[-10, 10],
z_range=[-10, 10],
h=1,
)
# Point = [-6, -6, -6]
potential_at_point = potential_volume[4][4][4]
expected_potential = charge.potential([-6, -6, -6])
np.testing.assert_equal(potential_at_point, expected_potential)
def test_field_volume_at_point_equal_class_field(self):
charge = Charge(self.position_1, self.charge)
field_volume = volume.field(
[charge],
x_range=[-10, 10],
y_range=[-10, 10],
z_range=[-10, 10],
h=1,
)
# Point = [-10, -6, -3]
field_at_point = field_volume[0][4][7]
expected_field = charge.field([-10, -6, -3])
np.testing.assert_equal(field_at_point, expected_field)
def test_two_charge_field_volume_eq_sum_of_class_field(self):
charges = [Charge(self.position_1, self.charge)]
charges.append(Charge(self.position_2, -self.charge))
field_volume = volume.field(
charges,
x_range=[-10, 10],
y_range=[-10, 10],
z_range=[-10, 10],
h=1,
)
# Point = [-6, -5, -3]
field_at_point = field_volume[4][5][7]
expected_field = np.add(charges[0].field([-6, -5, -3]),
charges[1].field([-6, -5, -3]))
np.testing.assert_equal(field_at_point, expected_field)
def test_neg_gradient_of_potiental_returns_field(self):
pos = [0, 0, 0]
charge = 7e-9
testObj = Charge(pos, charge)
ppos = [1, 2, -1]
h = 0.001
potential_grid = np.empty([3, 3, 3], dtype=object)
x = np.linspace(ppos[0] - h, ppos[0] + h, 3)
y = np.linspace(ppos[1] - h, ppos[1] + h, 3)
z = np.linspace(ppos[2] - h, ppos[2] + h, 3)
for (i, j, k), _ in np.ndenumerate(potential_grid):
potential_grid[i][j][k] = testObj.potential([x[i], y[j], z[k]])
xgrad, ygrad, zgrad = np.gradient(potential_grid, h)
grad_potential = np.array(
[xgrad[1, 1, 1], ygrad[1, 1, 1], zgrad[1, 1, 1]])
electric_field = testObj.field(ppos)
np.testing.assert_allclose(-grad_potential, electric_field, atol=1e-1)
def test_two_charge_potential_volume_eq_sum_of_class_potential(self):
charges = [Charge(self.position_1, self.charge)]
charges.append(Charge(self.position_2, -self.charge))
potential_volume = volume.potential(
charges,
x_range=[-10, 10],
y_range=[-10, 10],
z_range=[-10, 10],
h=1,
)
# Point = [-6, -5, -3]
potential_at_point = potential_volume[4][5][7]
expected_potential = np.add(
charges[0].potential([-6, -5, -3]),
charges[1].potential([-6, -5, -3]),
)
np.testing.assert_equal(potential_at_point, expected_potential)
def test_field_returns_singleton_dim_for_single_slice(self):
charge = Charge(self.position_1, self.charge)
field_volume = volume.field(
[charge],
x_range=[-10, 10],
y_range=[1, 1],
z_range=[-10, 10],
h=0.1,
)
expected_shape = (201, 1, 201)
actual_shape = field_volume.shape
np.testing.assert_equal(actual_shape, expected_shape)
def test_q_decorator_equal_to_initialized_charge_value(self):
testObj = Charge(self.positionList, self.charge)
self.assertEqual(testObj.q, self.charge)
def test_potential_returns_nan_at_particle_position(self):
testObj = Charge(self.positionList, self.charge)
ppos = self.positionList
self.assertTrue(np.isnan(testObj.potential(ppos)))
def test_that_3D_position_list_returns_an_object_of_type_Charge(self):
assert isinstance(Charge(self.positionList, self.charge), Charge)
def test_Charge_object_has_parent_type_Particle(self):
assert isinstance(Charge(self.positionList, self.charge), Particle)
def test_charge_property_equal_to_initialized_value(self):
testObj = Charge(self.positionList, self.charge)
self.assertEqual(testObj.charge, self.charge)
def test_field_returns_nan_at_particle_position(self):
testObj = Charge(self.positionList, self.charge)
fpos = self.positionList
self.assertTrue(np.isnan(testObj.field(fpos)).all())