def test_calculate_drag_should_calculate_correctly():
density = 2
velocity = 1
coef = 0.5
area = 10
expected_drag = 5
d = Drag(shape='cube', length=2)
drag = d.calculate_drag(coef, density, area, velocity)
assert expected_drag == drag
def test_drag_should_report_correctly_for_velocity():
d = Drag(velocity=1.0, shape='sphere', diameter=5.0)
expected_drag = 4729.5
assert np.isclose(expected_drag,
d.drag,
rtol=1e0,
atol=1e-02,
equal_nan=False)
def test_drag_should_report_zero_for_no_velocity():
d = Drag(shape='sphere', diameter=10)
assert 0.0 == d.drag
def test_drag_get_area_by_property():
d = Drag(shape='sphere', diameter=4.2)
expected_area = np.pi * ((4.2 / 2)**2)
assert expected_area == d.area
def test_drag_get_drag_coefficient_by_property():
d = Drag(shape='cube', length=14)
assert 1.05 == d.drag_coefficient
def test_drag_init_should_fail_if_cube_length_is_not_number():
with pytest.raises(ValueError):
d = Drag(shape='cube', length='a')
def test_drag_init_should_fail_if_cube_doesnt_include_length():
with pytest.raises(KeyError):
d = Drag(shape='cube')
def test_drag_init_should_fail_if_diameter_is_not_number():
with pytest.raises(ValueError):
d = Drag(shape='cone', diameter='a')
def test_drag_init_should_accept_length_of_side_for_non_spherical():
d = Drag(shape='cube', length=4)
area = 4**2
assert d._area == area
def test_drag_init_should_fail_if_circle_shape_doesnt_include_diameter():
with pytest.raises(KeyError):
d = Drag(shape='sphere')
def test_drag_init_should_accept_diameter_if_valid_shape():
d = Drag(shape='sphere', diameter=5.0)
area = np.pi * ((5.0 / 2)**2)
assert d._area == area
def test_drag_init_should_fail_if_shape_not_included():
with pytest.raises(KeyError):
d = Drag()
def test_drag_velocity_setter_raises_error_for_non_number():
d = Drag(shape='sphere', diameter=10)
with pytest.raises(ValueError):
d.velocity = 'now'
def test_drag_init_should_fail_if_shape_input_invalid():
with pytest.raises(ValueError):
d = Drag(shape='Rabbit')
def test_drag_velocity_setter():
d = Drag(shape='sphere', diameter=10)
d.velocity = 1144.22
assert 1144.22 == d.velocity
def test_drag_density_setter():
d = Drag(shape='sphere', diameter=10)
d.density = 2222.2
assert 2222.2 == d.density
