硒-能见度_元素_定位:__init __()恰好接受2个参数(给定3个) [英] Selenium - visibility_of_element_located: __init__() takes exactly 2 arguments (3 given)

问题描述

我在使用Selenium Python绑定的测试代码中遇到此错误:

I am getting this error in my test code that uses Selenium Python Bindings:

>           twitter_campaigns = wait.until(EC.visibility_of_element_located(By.CSS_SELECTOR, TWITTER_CAMPAIGNS))
E           TypeError: __init__() takes exactly 2 arguments (3 given)

这就是我正在执行的操作:

And this is what Im executing:

class TestTwitter(TestLogin, TestBuying):

    def setup(self, timeout=10):
        self.driver = webdriver.Firefox()
        self.driver.get(BASEURL)
        self.driver.implicitly_wait(timeout)

    def test_campaigns_loaded(self, timeout=10):
        self.signin_action()
        self.view_twitter_dashboard()
        self.select_brand()
        wait = WebDriverWait(self.driver, timeout)
        twitter_campaigns = wait.until(EC.visibility_of_element_located(By.CSS_SELECTOR, TWITTER_CAMPAIGNS))
        assert True == twitter_campaigns

    def teardown(self):
        self.driver.close()

所以我想知道为什么为什么在所有类上我都没有定义上述__init__()方法，而是在pytest之后定义了setUp和tearDown方法，从而导致上述错误.任何想法为何要使用3个参数?

So I'm wondering Why Im getting the above errors, on all the classes I haven't defined an __init__() method instead I defined a setUp and tearDown methods as pytest follow. Any ideas why is taking 3 args?

推荐答案

您应该问的问题不是为什么为什么要占用3个参数"，而是"什么" >需要3个参数".您的回溯是指代码中非常特定的一行，而这正是问题所在.

The question you should be asking is not "why is it taking 3 args", but "what is taking 3 args". Your traceback refers to a very specific line in code, and it is there where the problem lies.

根据此处的 Selenium Python 文档，

According to the Selenium Python docs here, the selenium.webdriver.support.expected_conditions.visibility_of_element_located should be called with a tuple; it is not a function, but actually a class, whose initializer expects just 1 argument beyond the implicit self:

class visibility_of_element_located(object):
   # ...
   def __init__(self, locator):
       # ...

因此，您需要使用两个嵌套括号来调用visibility_of_element_located:

Thus, you need to call the visibility_of_element_located with two nested parentheses:

wait.until(EC.visibility_of_element_located( ( By.CSS_SELECTOR, TWITTER_CAMPAIGNS ) ))

这意味着visibility_of_element_located.__init__将使用仅预期的2个参数调用:而不是3个参数self，By.CSS_SELECTOR和TWITTER_CAMPAIGNS:隐式的self和定位符:一个(type, expression)元组.

Which means that instead of 3 arguments self, By.CSS_SELECTOR and TWITTER_CAMPAIGNS, the visibility_of_element_located.__init__ will be invoked with just expected 2 arguments: the implicit self and the locator: a (type, expression) tuple.

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