Selenium - visibility_of_element_located：__ init __（）只需2个参数（给定3个）

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

我在使用Selenium Python Bindings的测试代码中收到此错误：

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

And this is what Im executing:

这就是我执行的：

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()

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?

所以我想知道为什么我得到上面的错误，在我没有定义__init __（）方法的所有类中，我将setUp和tearDown方法定义为pytest follow。任何想法为什么要采取3 args？

1 个解决方案

#1

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.

你应该问的问题不是“为什么它采取3 args”，而是“什么是3 args”。您的回溯是指代码中的一个非常具体的行，它存在问题所在。

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:

根据这里的Selenium Python文档，应该使用元组调用selenium.webdriver.support.expected_conditions.visibility_of_element_located;它不是一个函数，而是一个实际上是一个类，它的初始化程序只需要一个超出隐式self的参数：

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

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

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

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

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.

这意味着，而不是3个参数self，By.CSS_SELECTOR和TWITTER_CAMPAIGNS，visibility_of_element_located .__ init__将使用预期的2个参数调用：隐式self和定位器：a（type，expression）元组。