python 使用装饰器提示：TypeError: wrapper() takes no arguments (1 given)

tool.py
def LogClear(fn):
def wrapper():
os.system("adb logcat -c")
print 'logclear'
fn()
return wrapper

Calc.py
class Calc(unittest.TestCase):
@LogClear
def test_calc(self):
self.driver.start_activity('com.google.android.calculator','com.android.calculator2.Calculator')
self.driver.find_element_by_id("com.google.android.calculator:id/digit_4").click()
res =self.driver.find_element_by_id("com.google.android.calculator:id/formula").text
AssertAct(self, res,'5','the result of calc is not correct',get_mod())

执行，提示：TypeError: wrapper() takes no arguments (1 given)

其实要添加在装饰器上添加一个参数：

tool.pydef LogClear(fn):def wrapper(self):os.system("adb logcat -c")print 'logclear'fn(self)return wrapper