Automated test series selenium three kinds of waiting for detailed explanation

The first and simplest way is to force waiting sleep(time), Compulsory transfer procedure, etc time Second time , Whether or not the program can keep up with the speed , Or has it arrived ahead of time , We all have to wait time Duration .

The following code case shows :

from selenium import webdriverfrom time
import sleepdriver = webdriver.Chrome()
driver.get('http://www.1000phone.com')
sleep(5) #  Mandatory waiting 5 Seconds before proceeding to the next step 
print(driver.current_url)driver.quit()

This is called forced waiting , Whether your browser is loaded or not , The program has to wait 5 second ,5 One second to , Continue with the following code , Useful as a debugging tool , Sometimes you can wait like this in the code , However, it is not recommended to always wait in this way , Too rigid , Seriously affect the execution speed of the program .

Two . An implicit wait

The second is implicit waiting ,implicitly_wait(time)  The meaning of implicit waiting is ： Sun Wukong and Yang Jian agreed , Wherever the monkey king goes , We have to wait for Yang Jian time second , If Yang Jian comes during this time , Then they immediately set out to fight monsters , If Yang Jian doesn't arrive within the specified time , Then the monkey king went by himself , Naturally, let's wait for Yang Jian to throw the exception .

As shown in the following code :

from selenium import webdriver
from time import sleep
driver = webdriver.Chrome()driver.implicitly_wait(10)#  An implicit wait , The longest wait 10 second driver.get('http://www.1000phone.com')
print(driver.current_url)
driver.quit()

Implicit waiting is setting a maximum waiting time , If the web page is loaded within the specified time , Then go to the next step , Otherwise, wait until the deadline , Then go to the next step .

Note that there is a drawback , That is, the program will wait for the whole page to load , In other words, generally you see that the small circle in the browser tab bar doesn't rotate any more , To take the next step , But sometimes the elements the page wants are already loaded , But because of the individual js Things like that are very slow , You still have to wait until the page is complete to go to the next step .

I want to wait until the elements I want come out and what to do next ？ Is there a way to , It depends on selenium Another way to wait —— Explicit waiting WebDriverWait 了 . One thing to note is that ： Implicit wait for the whole driver All the cycles work , So just set it once , I've seen people treat implicit waiting as sleep In use , Come wherever you go .

3、 ... and . Explicit waiting

The third is to explicitly wait ,WebDriverWait, With this kind of until() and until_not() Method , We can wait flexibly according to the judging conditions .

Its main meaning is ： Program every time Take a second , If the conditions hold , Then go to the next step , Otherwise, keep waiting , Until the set maximum time is exceeded , Then throw TimeoutException.

As shown in the following code :

from selenium import webdriver
from selenium.webdriver.support.wait import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.webdriver.common.by import By
driver = webdriver.Chrome()
#  Implicit waiting and explicit waiting can be used at the same time , But should pay attention to ： The longest waiting time is the greater of the two 
driver.implicitly_wait(10) driver.get('http://www.1000phone.com')
locator = (By.LINK_TEXT, ' Discipline ')
try:
WebDriverWait(driver, 20, 0.5).until(EC.presence_of_element_located(locator)) print(driver.find_element_by_link_text(' Discipline ').get_attribute('href'))
finally:
driver.close()

We set implicit wait and explicit wait , In other operations , Implicit waiting plays a decisive role , stay WebDriverWait... Explicit waiting plays a major role in , But here's the thing ： The longest waiting time depends on the larger of the two , As in the above example 20, If the implicit wait time > Explicit wait time , Then the maximum waiting time of the sentence code is equal to the implicit waiting time .

Explicitly wait for the method to be called :

WebDriverWait(driver, Time out period , Call frequency , Ignore exceptions ).until( Executable method , Information returned on timeout )

Here is the special note until or until_not The executable method in method Parameters

So let's take a look at selenium What are the conditions provided ：expected_conditions yes selenium A module of , It contains a series of conditions that can be used to judge ：
selenium.webdriver.support.expected_conditions（ modular ）

1. Verify the parameters passed in title Whether equal to or contained in driver.title

title_is
title_contains

Automated test series -Selenium Three kinds of waiting for detailed explanation

2022-07-24 20:53· Test waiter

One . Mandatory waiting sleep

The first and simplest way is to force waiting sleep(time), Compulsory transfer procedure, etc time Second time , Whether or not the program can keep up with the speed , Or has it arrived ahead of time , We all have to wait time Duration .

The following code case shows :

from selenium import webdriverfrom time
import sleepdriver = webdriver.Chrome()
driver.get('http://www.1000phone.com')
sleep(5) #  Mandatory waiting 5 Seconds before proceeding to the next step 
print(driver.current_url)driver.quit()

This is called forced waiting , Whether your browser is loaded or not , The program has to wait 5 second ,5 One second to , Continue with the following code , Useful as a debugging tool , Sometimes you can wait like this in the code , However, it is not recommended to always wait in this way , Too rigid , Seriously affect the execution speed of the program .

Two . An implicit wait

The second is implicit waiting ,implicitly_wait(time)  The meaning of implicit waiting is ： Sun Wukong and Yang Jian agreed , Wherever the monkey king goes , We have to wait for Yang Jian time second , If Yang Jian comes during this time , Then they immediately set out to fight monsters , If Yang Jian doesn't arrive within the specified time , Then the monkey king went by himself , Naturally, let's wait for Yang Jian to throw the exception .

As shown in the following code :

from selenium import webdriver
from time import sleep
driver = webdriver.Chrome()driver.implicitly_wait(10)#  An implicit wait , The longest wait 10 second driver.get('http://www.1000phone.com')
print(driver.current_url)
driver.quit()

Implicit waiting is setting a maximum waiting time , If the web page is loaded within the specified time , Then go to the next step , Otherwise, wait until the deadline , Then go to the next step .

Note that there is a drawback , That is, the program will wait for the whole page to load , In other words, generally you see that the small circle in the browser tab bar doesn't rotate any more , To take the next step , But sometimes the elements the page wants are already loaded , But because of the individual js Things like that are very slow , You still have to wait until the page is complete to go to the next step .

I want to wait until the elements I want come out and what to do next ？ Is there a way to , It depends on selenium Another way to wait —— Explicit waiting WebDriverWait 了 . One thing to note is that ： Implicit wait for the whole driver All the cycles work , So just set it once , I've seen people treat implicit waiting as sleep In use , Come wherever you go .

3、 ... and . Explicit waiting

The third is to explicitly wait ,WebDriverWait, With this kind of until() and until_not() Method , We can wait flexibly according to the judging conditions .

Its main meaning is ： Program every time Take a second , If the conditions hold , Then go to the next step , Otherwise, keep waiting , Until the set maximum time is exceeded , Then throw TimeoutException.

As shown in the following code :

from selenium import webdriver
from selenium.webdriver.support.wait import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.webdriver.common.by import By
driver = webdriver.Chrome()
#  Implicit waiting and explicit waiting can be used at the same time , But should pay attention to ： The longest waiting time is the greater of the two 
driver.implicitly_wait(10) driver.get('http://www.1000phone.com')
locator = (By.LINK_TEXT, ' Discipline ')
try:
WebDriverWait(driver, 20, 0.5).until(EC.presence_of_element_located(locator)) print(driver.find_element_by_link_text(' Discipline ').get_attribute('href'))
finally:
driver.close()

We set implicit wait and explicit wait , In other operations , Implicit waiting plays a decisive role , stay WebDriverWait... Explicit waiting plays a major role in , But here's the thing ： The longest waiting time depends on the larger of the two , As in the above example 20, If the implicit wait time > Explicit wait time , Then the maximum waiting time of the sentence code is equal to the implicit waiting time .

Explicitly wait for the method to be called :

WebDriverWait(driver, Time out period , Call frequency , Ignore exceptions ).until( Executable method , Information returned on timeout )

Here is the special note until or until_not The executable method in method Parameters

So let's take a look at selenium What are the conditions provided ：expected_conditions yes selenium A module of , It contains a series of conditions that can be used to judge ：
selenium.webdriver.support.expected_conditions（ modular ）

1. Verify the parameters passed in title Whether equal to or contained in driver.title

title_is
title_contains

2. Verify that the element appears , The parameters passed in are of tuple type locator, Such as (By.ID, ‘kw’)

presence_of_element_located
presence_of_all_elements_located

3. Verify that the element is visible , The first two incoming parameters are of tuple type locator, The third one came in WebElement The first and the third are essentially the same

visibility_of_element_located
invisibility_of_element_located
visibility_of

4. Determine whether a piece of text appears in an element , Of a judging element text, Of a judging element value

text_to_be_present_in_element
text_to_be_present_in_element_value

condition, And until、until_not A combination can make a lot of judgments , If it can be flexibly packaged by itself , Will greatly improve the stability of the script .

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