kwargs is empty with decorator about decorator HOT 3 CLOSED

This is absolutely correct. Your function (i.e. test(self, x, y, z)) has positional arguments x, y, z and has no keyword arguments. You probably misunderstand how Python argument passing works:
test.test(x=2,y=2,z=4) is passing positional arguments, not keyword arguments.

from decorator.

But if I create the decorator with out @decorator.decorator, it will return exactly what I want:

def test_decorator_raw(f):
    def _decorator_raw(*args, **kwargs):
        print('check args:')
        print(args)
        print('check kwargs')
        print(kwargs)
        return f(*args, **kwargs)
    return _decorator_raw

class TestObject(object):

    @test_decorator_raw
    def test_raw(self, x, y, z):
        return x + y +z

test = TestObject()
test.test_raw(x=2,y=2,z=4)

The output is:

check args:
(<__main__.TestObject object at 0x7f9b3c2a6cd0>,)
check kwargs
{'y': 2, 'x': 2, 'z': 4}

from decorator.

Then use test_decorator_raw, but it is not preserving the signature, so it wrong for the goals of the decorator module.

from decorator.