显示等待

1、导包：

from selenium.webdriver.support.wait import WebDriverWait
from selenium.webdriver.support import expected_conditions as ec

2、使用技巧

wait = WebDriverWait(self.driver, 5)
wait.until(ec.text_to_be_present_in_element((by.XPATH, '//*[@id="hasContentDiv"]/div[1]/h2'), '章节列表'))

3、源码解析

class WebDriverWait(Generic[D]):
    def __init__(
        self,
        driver: D,   
        timeout: float,  #超时时长
        poll_frequency: float = POLL_FREQUENCY,  #轮询时间间隔
        ignored_exceptions: typing.Optional[WaitExcTypes] = None, #忽略异常
    ):




def until(self, method: Callable[[D], Union[Literal[False], T]], message: str = "") -> T:
    """Calls the method provided with the driver as an argument until the \
    return value does not evaluate to ``False``.

    :param method: callable(WebDriver)
    :param message: optional message for :exc:`TimeoutException`
    :returns: the result of the last call to `method`
    :raises: :exc:`selenium.common.exceptions.TimeoutException` if timeout occurs
    """
    screen = None
    stacktrace = None

    end_time = time.monotonic() + self._timeout
    while True:
        try:
            value = method(self._driver) # 调用传入的方法，有返回值则正常返回
            if value:
                return value
        except self._ignored_exceptions as exc:
            screen = getattr(exc, "screen", None)
            stacktrace = getattr(exc, "stacktrace", None)
        time.sleep(self._poll) # 出现异常或者无返回值时，等待轮询时间间隔
        if time.monotonic() > end_time:
            break # 达到超时时长，循环结束
    raise TimeoutException(message, screen, stacktrace) # 达到超时时长，抛出异常
    
    
until方法传入可调用对象类型method、异常放回字段message。找到element或者返回true时循环结束。

def until_not(self, method: Callable[[D], T], message: str = "") -> Union[T, Literal[True]]:
    ...
until_not方法功能与until相反。未找到element或者返回false时循环结束。

4、until方法入参中常用的method

title_is(title: str)-> Callable[[WebDriver], bool]：标题是某内容

title_contains(title: str)-> Callable[[WebDriver], bool]：标题包含某内容

presence_of_element_located(locator: Tuple[str, str])-> Callable[[WebDriverOrWebElement], WebElement]：元素加载出，传入定位元组，如(By.ID, 'p')

url_contains(url: str) -> Callable[[WebDriver], bool]：当前url是否包含某个字段

url_matches(pattern: str) -> Callable[[WebDriver], bool]：当前url是否包含传入的pattern

url_to_be(url: str) -> Callable[[WebDriver], bool]：当前url是否为传入字段

url_changes(url: str) -> Callable[[WebDriver], bool]：当前url是否不等于传入字段

visibility_of_element_located(
    locator: Tuple[str, str]
) -> Callable[[WebDriverOrWebElement], Union[Literal[False], WebElement]]:元素可见，传入定位元组

visibility_of(element: WebElement) -> Callable[[Any], Union[Literal[False], WebElement]]:可见，传入元素对象

presence_of_all_elements_located(locator: Tuple[str, str]) -> Callable[[WebDriverOrWebElement], List[WebElement]]:所有元素加载出
    
visibility_of_any_elements_located(locator: Tuple[str, str]) -> Callable[[WebDriverOrWebElement], List[WebElement]]:判断页面至少有一个元素可见 visible，传入locator，一旦定位就返回 the list of located WebElements；不可见（元素隐藏 或是 完全不存在，一个都没有）返回的是 空列表；
和显式等待结合后， 符合 最少存在一个WebElement的 返回符合定位元素条件WebElement的列表，不可见（元素隐藏 或是 完全不存在的）显式等待+报错;

visibility_of_all_elements_located(
    locator: Tuple[str, str]
) -> Callable[[WebDriverOrWebElement], Union[List[WebElement], Literal[False]]]:判断页面all elements存在且可见 visible
all elements are present and visible；传入locator，全部符合的 就返回 the list of located and visible WebElements；不能全部符合的返回False；不存在的元素返回 空列表； 和显式等待结合后，符合 全部可见WebElement的 返回符合定位元素条件WebElement的列表，找不到元素的 + WebElement不能全部可见的 显式等待+报错

text_to_be_present_in_element：某个元素文本包含某文字

text_to_be_present_in_element_value：某个元素值包含某文字

text_to_be_present_in_element_attribute(
    locator: Tuple[str, str], attribute_: str, text_: str
) -> Callable[[WebDriverOrWebElement], bool]：某个元素属性包含某文字

frame_to_be_available_and_switch_to_it(locator: Union[Tuple[str, str], str]) -> Callable[[WebDriver], bool]:frame加载并切换
    
invisibility_of_element_located(
    locator: Union[WebElement, Tuple[str, str]]
) -> Callable[[WebDriverOrWebElement], Union[WebElement, bool]]:元素是否不可见
    
invisibility_of_element(
    element: Union[WebElement, Tuple[str, str]]
) -> Callable[[WebDriverOrWebElement], Union[WebElement, bool]]:元素是否不可见
    
element_to_be_clickable(
    mark: Union[WebElement, Tuple[str, str]]
) -> Callable[[WebDriverOrWebElement], Union[Literal[False], WebElement]]:元素是否可点击
    
staleness_of(element: WebElement) -> Callable[[Any], bool]:判断一个元素是否仍在DOM，可判断页面是否已经刷新
    
element_to_be_selected(element: WebElement) -> Callable[[Any], bool]:元素是否可选择，传元素对象
    
element_located_to_be_selected(locator: Tuple[str, str]) -> Callable[[WebDriverOrWebElement], bool]:元素可选择，传入定位元组

    
element_selection_state_to_be(element: WebElement, is_selected: bool) -> Callable[[Any], bool]:传入元素对象以及状态，相等返回True，否则返回False
    
element_located_selection_state_to_be(
    locator: Tuple[str, str], is_selected: bool
) -> Callable[[WebDriverOrWebElement], bool]:传入定位元组以及状态，相等返回True，否则返回False
    
    
number_of_windows_to_be(num_windows: int) -> Callable[[WebDriver], bool]:特定窗口数和实际窗口数是否一致
    
new_window_is_opened(current_handles: List[str]) -> Callable[[WebDriver], bool]:新窗口是否打开 
    
alert_is_present() -> Callable[[WebDriver], Union[Alert, Literal[False]]]:是否出现Alert
    
element_attribute_to_include(locator: Tuple[str, str], attribute_: str) -> Callable[[WebDriverOrWebElement], bool]:是否包含某个属性
    
any_of(*expected_conditions: Callable[[D], T]) -> Callable[[D], Union[Literal[False], T]]:对多个期望条件中的任何一个为真则为真。
    
all_of(
    *expected_conditions: Callable[[D], Union[T, Literal[False]]]
) -> Callable[[D], Union[List[T], Literal[False]]]:对多个期望条件中的所有条件为真则为真
    
none_of(*expected_conditions: Callable[[D], Any]) -> Callable[[D], bool]:对多个期望条件中的所有条件为假则为真

5、日常用法

可用作元素查找或者断言动作是否生效