def test_get_depotwert_by():
component_under_test = Depotauszuege()
component_under_test.add(datum('01.01.2020'), '1isin', '1demokonto', 11)
component_under_test.add(datum('02.01.2020'), '1isin', '1demokonto', 200)
component_under_test.add(datum('02.01.2020'), '2isin', '1demokonto', 311)
component_under_test.add(datum('02.01.2020'), '1isin', '2demokonto', 400)
assert component_under_test.get_depotwert_by('1isin') == 600
def test_get_depotwert_by_with_empty_should_return_zero():
component_under_test = Depotauszuege()
assert component_under_test.get_depotwert_by('isin1') == 0