def test_multiple_filter(prefixes, count):
subset = filter_apps(apps_dict, prefixes)
assert len(subset) == count
subset = filter_apps(apps_set, prefixes)
assert len(subset) == count
def test_list_filter(prefix, count):
subset = filter_apps(apps_list, [prefix])
assert len(subset) == count
def test_dict_void_filter():
subset = filter_apps(apps_dict, [])
assert subset == apps_dict
def test_none_filter():
subset = filter_apps(None, ['a', 'b', 'c'])
assert subset is None
def test_set_filter(prefix, count):
subset = filter_apps(set(apps), [prefix])
assert len(subset) == count