selenium-模块概述（1）

Selenium是一个用于Web应用程序自动化测试工具。Selenium测试直接运行在浏览器中，就像真正的用户在操作一样。

1.目录结构如下：

D:\soft\python36\Lib\site-packages\selenium>tree /f
卷 新加卷 的文件夹 PATH 列表
卷序列号为 960E-961E
D:.
│  __init__.py
│
├─common
│  │  exceptions.py
│  │  __init__.py
│  │
│  └─__pycache__
│          exceptions.cpython-36.pyc
│          __init__.cpython-36.pyc
│
├─webdriver
│  │  __init__.py
│  │
│  ├─android
│  │  │  webdriver.py
│  │  │  __init__.py
│  │  │
│  │  └─__pycache__
│  │          webdriver.cpython-36.pyc
│  │          __init__.cpython-36.pyc
│  │
│  ├─blackberry
│  │  │  webdriver.py
│  │  │  __init__.py
│  │  │
│  │  └─__pycache__
│  │          webdriver.cpython-36.pyc
│  │          __init__.cpython-36.pyc
│  │
│  ├─chrome
│  │  │  options.py
│  │  │  remote_connection.py
│  │  │  service.py
│  │  │  webdriver.py
│  │  │  __init__.py
│  │  │
│  │  └─__pycache__
│  │          options.cpython-36.pyc
│  │          remote_connection.cpython-36.pyc
│  │          service.cpython-36.pyc
│  │          webdriver.cpython-36.pyc
│  │          __init__.cpython-36.pyc
│  │
│  ├─common
│  │  │  action_chains.py
│  │  │  alert.py
│  │  │  by.py
│  │  │  desired_capabilities.py
│  │  │  keys.py
│  │  │  proxy.py
│  │  │  service.py
│  │  │  touch_actions.py
│  │  │  utils.py
│  │  │  __init__.py
│  │  │
│  │  ├─actions
│  │  │  │  action_builder.py
│  │  │  │  input_device.py
│  │  │  │  interaction.py
│  │  │  │  key_actions.py
│  │  │  │  key_input.py
│  │  │  │  mouse_button.py
│  │  │  │  pointer_actions.py
│  │  │  │  pointer_input.py
│  │  │  │  __init__.py
│  │  │  │
│  │  │  └─__pycache__
│  │  │          action_builder.cpython-36.pyc
│  │  │          input_device.cpython-36.pyc
│  │  │          interaction.cpython-36.pyc
│  │  │          key_actions.cpython-36.pyc
│  │  │          key_input.cpython-36.pyc
│  │  │          mouse_button.cpython-36.pyc
│  │  │          pointer_actions.cpython-36.pyc
│  │  │          pointer_input.cpython-36.pyc
│  │  │          __init__.cpython-36.pyc
│  │  │
│  │  ├─html5
│  │  │  │  application_cache.py
│  │  │  │  __init__.py
│  │  │  │
│  │  │  └─__pycache__
│  │  │          application_cache.cpython-36.pyc
│  │  │          __init__.cpython-36.pyc
│  │  │
│  │  └─__pycache__
│  │          action_chains.cpython-36.pyc
│  │          alert.cpython-36.pyc
│  │          by.cpython-36.pyc
│  │          desired_capabilities.cpython-36.pyc
│  │          keys.cpython-36.pyc
│  │          proxy.cpython-36.pyc
│  │          service.cpython-36.pyc
│  │          touch_actions.cpython-36.pyc
│  │          utils.cpython-36.pyc
│  │          __init__.cpython-36.pyc
│  │
│  ├─edge
│  │  │  options.py
│  │  │  service.py
│  │  │  webdriver.py
│  │  │  __init__.py
│  │  │
│  │  └─__pycache__
│  │          options.cpython-36.pyc
│  │          service.cpython-36.pyc
│  │          webdriver.cpython-36.pyc
│  │          __init__.cpython-36.pyc
│  │
│  ├─firefox
│  │  │  extension_connection.py
│  │  │  firefox_binary.py
│  │  │  firefox_profile.py
│  │  │  options.py
│  │  │  remote_connection.py
│  │  │  service.py
│  │  │  webdriver.py
│  │  │  webdriver.xpi
│  │  │  webdriver_prefs.json
│  │  │  webelement.py
│  │  │  __init__.py
│  │  │
│  │  ├─amd64
│  │  │      x_ignore_nofocus.so
│  │  │
│  │  ├─x86
│  │  │      x_ignore_nofocus.so
│  │  │
│  │  └─__pycache__
│  │          extension_connection.cpython-36.pyc
│  │          firefox_binary.cpython-36.pyc
│  │          firefox_profile.cpython-36.pyc
│  │          options.cpython-36.pyc
│  │          remote_connection.cpython-36.pyc
│  │          service.cpython-36.pyc
│  │          webdriver.cpython-36.pyc
│  │          webelement.cpython-36.pyc
│  │          __init__.cpython-36.pyc
│  │
│  ├─ie
│  │  │  options.py
│  │  │  service.py
│  │  │  webdriver.py
│  │  │  __init__.py
│  │  │
│  │  └─__pycache__
│  │          options.cpython-36.pyc
│  │          service.cpython-36.pyc
│  │          webdriver.cpython-36.pyc
│  │          __init__.cpython-36.pyc
│  │
│  ├─opera
│  │  │  options.py
│  │  │  webdriver.py
│  │  │  __init__.py
│  │  │
│  │  └─__pycache__
│  │          options.cpython-36.pyc
│  │          webdriver.cpython-36.pyc
│  │          __init__.cpython-36.pyc
│  │
│  ├─phantomjs
│  │  │  service.py
│  │  │  webdriver.py
│  │  │  __init__.py
│  │  │
│  │  └─__pycache__
│  │          service.cpython-36.pyc
│  │          webdriver.cpython-36.pyc
│  │          __init__.cpython-36.pyc
│  │
│  ├─remote
│  │  │  command.py
│  │  │  errorhandler.py
│  │  │  file_detector.py
│  │  │  getAttribute.js
│  │  │  isDisplayed.js
│  │  │  mobile.py
│  │  │  remote_connection.py
│  │  │  switch_to.py
│  │  │  utils.py
│  │  │  webdriver.py
│  │  │  webelement.py
│  │  │  __init__.py
│  │  │
│  │  └─__pycache__
│  │          command.cpython-36.pyc
│  │          errorhandler.cpython-36.pyc
│  │          file_detector.cpython-36.pyc
│  │          mobile.cpython-36.pyc
│  │          remote_connection.cpython-36.pyc
│  │          switch_to.cpython-36.pyc
│  │          utils.cpython-36.pyc
│  │          webdriver.cpython-36.pyc
│  │          webelement.cpython-36.pyc
│  │          __init__.cpython-36.pyc
│  │
│  ├─safari
│  │  │  permissions.py
│  │  │  remote_connection.py
│  │  │  service.py
│  │  │  webdriver.py
│  │  │  __init__.py
│  │  │
│  │  └─__pycache__
│  │          permissions.cpython-36.pyc
│  │          remote_connection.cpython-36.pyc
│  │          service.cpython-36.pyc
│  │          webdriver.cpython-36.pyc
│  │          __init__.cpython-36.pyc
│  │
│  ├─support
│  │  │  abstract_event_listener.py
│  │  │  color.py
│  │  │  events.py
│  │  │  event_firing_webdriver.py
│  │  │  expected_conditions.py
│  │  │  select.py
│  │  │  ui.py
│  │  │  wait.py
│  │  │  __init__.py
│  │  │
│  │  └─__pycache__
│  │          abstract_event_listener.cpython-36.pyc
│  │          color.cpython-36.pyc
│  │          events.cpython-36.pyc
│  │          event_firing_webdriver.cpython-36.pyc
│  │          expected_conditions.cpython-36.pyc
│  │          select.cpython-36.pyc
│  │          ui.cpython-36.pyc
│  │          wait.cpython-36.pyc
│  │          __init__.cpython-36.pyc
│  │
│  ├─webkitgtk
│  │  │  options.py
│  │  │  service.py
│  │  │  webdriver.py
│  │  │  __init__.py
│  │  │
│  │  └─__pycache__
│  │          options.cpython-36.pyc
│  │          service.cpython-36.pyc
│  │          webdriver.cpython-36.pyc
│  │          __init__.cpython-36.pyc
│  │
│  └─__pycache__
│          __init__.cpython-36.pyc
│
└─__pycache__
        __init__.cpython-36.pyc

selenium目录结构

2.捕获异常可调用exceptions.py使用其中的相应方法

# 需要导入模块exceptions.py
from selenium.common import exceptions

# exceptions.py代码如下
class WebDriverException(Exception):
    """
    Base webdriver exception.
    """

    def __init__(self, msg=None, screen=None, stacktrace=None):
        self.msg = msg
        self.screen = screen
        self.stacktrace = stacktrace

    def __str__(self):
        exception_msg = "Message: %s\n" % self.msg
        if self.screen is not None:
            exception_msg += "Screenshot: available via screen\n"
        if self.stacktrace is not None:
            stacktrace = "\n".join(self.stacktrace)
            exception_msg += "Stacktrace:\n%s" % stacktrace
        return exception_msg

class ErrorInResponseException(WebDriverException):
    """
    Thrown when an error has occurred on the server side.

    This may happen when communicating with the firefox extension
    or the remote driver server.
    """
    def __init__(self, response, msg):
        WebDriverException.__init__(self, msg)
        self.response = response

class InvalidSwitchToTargetException(WebDriverException):
    """
    Thrown when frame or window target to be switched doesn't exist.
    """
    pass

class NoSuchFrameException(InvalidSwitchToTargetException):
    """
    Thrown when frame target to be switched doesn't exist.
    """
    pass

class NoSuchWindowException(InvalidSwitchToTargetException):
    """
    Thrown when window target to be switched doesn't exist.

    To find the current set of active window handles, you can get a list
    of the active window handles in the following way::

        print driver.window_handles

    """
    pass

class NoSuchElementException(WebDriverException):
    """
    Thrown when element could not be found.

    If you encounter this exception, you may want to check the following:
        * Check your selector used in your find_by...
        * Element may not yet be on the screen at the time of the find operation,
          (webpage is still loading) see selenium.webdriver.support.wait.WebDriverWait()
          for how to write a wait wrapper to wait for an element to appear.
    """
    pass

class NoSuchAttributeException(WebDriverException):
    """
    Thrown when the attribute of element could not be found.

    You may want to check if the attribute exists in the particular browser you are
    testing against.  Some browsers may have different property names for the same
    property.  (IE8's .innerText vs. Firefox .textContent)
    """
    pass

class StaleElementReferenceException(WebDriverException):
    """
    Thrown when a reference to an element is now "stale".

    Stale means the element no longer appears on the DOM of the page.

    Possible causes of StaleElementReferenceException include, but not limited to:
        * You are no longer on the same page, or the page may have refreshed since the element
          was located.
        * The element may have been removed and re-added to the screen, since it was located.
          Such as an element being relocated.
          This can happen typically with a javascript framework when values are updated and the
          node is rebuilt.
        * Element may have been inside an iframe or another context which was refreshed.
    """
    pass

class InvalidElementStateException(WebDriverException):
    """
    Thrown when a command could not be completed because the element is in an invalid state.

    This can be caused by attempting to clear an element that isn't both editable and resettable.
    """
    pass

class UnexpectedAlertPresentException(WebDriverException):
    """
    Thrown when an unexpected alert is appeared.

    Usually raised when when an expected modal is blocking webdriver form executing any
    more commands.
    """
    def __init__(self, msg=None, screen=None, stacktrace=None, alert_text=None):
        super(UnexpectedAlertPresentException, self).__init__(msg, screen, stacktrace)
        self.alert_text = alert_text

    def __str__(self):
        return "Alert Text: %s\n%s" % (self.alert_text, super(UnexpectedAlertPresentException, self).__str__())

class NoAlertPresentException(WebDriverException):
    """
    Thrown when switching to no presented alert.

    This can be caused by calling an operation on the Alert() class when an alert is
    not yet on the screen.
    """
    pass

class ElementNotVisibleException(InvalidElementStateException):
    """
    Thrown when an element is present on the DOM, but
    it is not visible, and so is not able to be interacted with.

    Most commonly encountered when trying to click or read text
    of an element that is hidden from view.
    """
    pass

class ElementNotInteractableException(InvalidElementStateException):
    """
    Thrown when an element is present in the DOM but interactions
    with that element will hit another element do to paint order
    """
    pass

class ElementNotSelectableException(InvalidElementStateException):
    """
    Thrown when trying to select an unselectable element.

    For example, selecting a 'script' element.
    """
    pass

class InvalidCookieDomainException(WebDriverException):
    """
    Thrown when attempting to add a cookie under a different domain
    than the current URL.
    """
    pass

class UnableToSetCookieException(WebDriverException):
    """
    Thrown when a driver fails to set a cookie.
    """
    pass

class RemoteDriverServerException(WebDriverException):
    """
    """
    pass

class TimeoutException(WebDriverException):
    """
    Thrown when a command does not complete in enough time.
    """
    pass

class MoveTargetOutOfBoundsException(WebDriverException):
    """
    Thrown when the target provided to the `ActionsChains` move()
    method is invalid, i.e. out of document.
    """
    pass

class UnexpectedTagNameException(WebDriverException):
    """
    Thrown when a support class did not get an expected web element.
    """
    pass

class InvalidSelectorException(NoSuchElementException):
    """
    Thrown when the selector which is used to find an element does not return
    a WebElement. Currently this only happens when the selector is an xpath
    expression and it is either syntactically invalid (i.e. it is not a
    xpath expression) or the expression does not select WebElements
    (e.g. "count(//input)").
    """
    pass

class ImeNotAvailableException(WebDriverException):
    """
    Thrown when IME support is not available. This exception is thrown for every IME-related
    method call if IME support is not available on the machine.
    """
    pass

class ImeActivationFailedException(WebDriverException):
    """
    Thrown when activating an IME engine has failed.
    """
    pass

class InvalidArgumentException(WebDriverException):
    """
    The arguments passed to a command are either invalid or malformed.
    """
    pass

class JavascriptException(WebDriverException):
    """
    An error occurred while executing JavaScript supplied by the user.
    """
    pass

class NoSuchCookieException(WebDriverException):
    """
    No cookie matching the given path name was found amongst the associated cookies of the
    current browsing context's active document.
    """
    pass

class ScreenshotException(WebDriverException):
    """
    A screen capture was made impossible.
    """
    pass

class ElementClickInterceptedException(WebDriverException):
    """
    The Element Click command could not be completed because the element receiving the events
    is obscuring the element that was requested clicked.
    """
    pass

class InsecureCertificateException(WebDriverException):
    """
    Navigation caused the user agent to hit a certificate warning, which is usually the result
    of an expired or invalid TLS certificate.
    """
    pass

class InvalidCoordinatesException(WebDriverException):
    """
    The coordinates provided to an interactions operation are invalid.
    """
    pass

class InvalidSessionIdException(WebDriverException):
    """
    Occurs if the given session id is not in the list of active sessions, meaning the session
    either does not exist or that it's not active.
    """
    pass

class SessionNotCreatedException(WebDriverException):
    """
    A new session could not be created.
    """
    pass

class UnknownMethodException(WebDriverException):
    """
    The requested command matched a known URL but did not match an method for that URL.
    """
    pass

common/exceptions.py

3.操作浏览器常会用到如下模块

4.原理

　　1.selenium client(python等语言编写的自动化测试脚本)初始化一个service服务，通过Webdriver启动浏览器驱动程序chromedriver.exe

　　2.通过RemoteWebDriver向浏览器驱动程序发送HTTP请求，浏览器驱动程序解析请求，打开浏览器，并获得sessionid，如果再次对浏览器操作需携带此id

　　3.打开浏览器，绑定特定的端口，把启动后的浏览器作为webdriver的remote server

　　3.打开浏览器后，所有的selenium的操作(访问地址，查找元素等)均通过RemoteConnection链接到remote server，然后使用execute方法调用_request方法通过urlib3向remote server发送请求

　　4.浏览器通过请求的内容执行对应动作

　　5.浏览器再把执行的动作结果通过浏览器驱动程序返回给测试脚本