diffit.py

def raise_msg(msg, path):
    if len(path) > 0:
        msg = 'At path {}: {}'.format('.'.join(path), msg)
    raise AssertionError(msg)

def list_diff(list1, list2, path):
    if len(list1) != len(list2):
        raise_msg('List lengths differ: {} vs {}'
                  .format(len(list1), len(list2)), path)
    for i, (obj1, obj2) in enumerate(zip(list1, list2)):
        diff(obj1, obj2, path + [str(i)])

def dict_diff(d1, d2, path):
    if set(d1.keys()) != set(d2.keys()):
        raise_msg('keys differ: {} vs {}'
                  .format(set(d1.keys()), set(d2.keys())), path)
    for k, v1 in d1.items():
        diff(v1, d2[k], path + [k])

def diff(obj1, obj2, path=None):
    if path is None:
        path = []
    if type(obj1) != type(obj2):
        raise_msg('Objects {} and {}, different types: {} vs {}'
                  .format(obj1, obj2, type(obj1), type(obj2)), path)
    elif isinstance(obj1, dict):
        dict_diff(obj1, obj2, path)
    elif isinstance(obj1, list):
        list_diff(obj1, obj2, path)
    elif obj1 != obj2:
        raise_msg('Not equal: {} vs {}'.format(obj1, obj2), path)