[test development] automatic test selenium (I)

What is automated testing

Automated testing refers to the automation of software testing , Run the application or system in the preset state , Preset conditions include normal and abnormal , Finally, evaluate the operation results . The process of transforming human driven test behavior into machine execution .

Common automated test tools ： QTP、selenium、Rational Robot 、jmeter、appium、soapui、Loadrunner wait

selenium It's a web Automated testing tools for , Many students who study automatic learning function begin to choose selenium , Compared to it QTP There are many advantages ：

• free , There's no need to crack it any more QTP And it's a big headache
• small , For different languages, it's just a package , and QTP Need to download and install 1 More than a G The program .
• This is also the most important point , No matter how familiar you used to be C、java、ruby、python、 Or both C# , You all Can pass selenium Complete automated testing , and QTP Only support VBS
• Support for multiple platforms ：windows、linux、MAC , Support for multiple browsers ：ie、ff、safari、opera、chrome
• Support the execution of distributed test cases , Test cases can be distributed to different test machines for execution , Equivalent to points The function of the hair machine .

The difference between automation tools and automation frameworks ？
Automated testing framework can generally be divided into two levels , The upper layer is to manage the development of the whole automatic test , Perform... And maintenance , In a relatively large project , It plays an important role , It can manage the entire automated test , Including the sequence of automated test case execution 、 Maintenance of test scripts 、 And centralized management of test cases 、 Test report and test task, etc . The lower layer is mainly the development of test scripts , Make full use of relevant testing tools , Build test driven , And complete the test business logic .

How to implement automation

Applicable objects of automated testing ：
Prerequisites for implementing automated testing ： Demand changes infrequently 、 Project cycle long enough 、 Automated test scripts are reusable

1. Projects with frequent demand changes , Automated scripts cannot be reused , Maintenance costs are too high , Low cost performance
2. The project cycle is short , The automatic script is not used much after preparation , Low cost performance
3. Projects with strong interaction , Projects requiring human intervention , Automation cannot be implemented

Suitable for automation projects ：
4. Product type project . Product based projects , The new version is an improvement on the old version , Items with little function , The old project must be tested repeatedly, but the new function must be tested again . Regression testing is the strength of automated testing , It can be a good way to verify whether you have introduced new defects , Whether the old defects have been corrected . To some extent, automated testing tools can be called regression testing tools .
5. Mechanical and frequent testing . You need to enter the same... Each time 、 A lot of data , And in a project The operation cycle is relatively long .

When to implement ?
If our automation implementation fails , Obviously , We did the job at an inopportune time .
Suggest ： Predictable requirements do not affect the design of automated test cases

How to implement automated testing
Simply speaking , The concrete implementation of automated testing , It should include the following seven processes .

1. analysis ： Overall grasp the system logic , Analyze the core architecture of the system .
2. Design ： Design test cases , Test cases should be clear enough , Wide coverage and excellent
3. Realization ： Implementation script , There are two requirements. One is to assert , The second is the rational use of parameterization .
4. perform ： Executing scripts is far from as simple as we think . We need to carefully analyze the causes of exceptions during script execution .
5. summary ： Analysis of test results , And the summary of testing process is the key to automatic testing .
6. maintain ： The maintenance of automated test scripts is a difficult but necessary problem .
7. analysis ： In the process of automated testing, deeply analyze the coverage risk of automated use cases and the cost of script maintenance .

Direction of development

1. Automate the execution of scripts , Maintenance and result analysis
2. Automated scripting
3. Design of automatic test scheme , Frame selection
4. Coding implementation of automatic test framework
5. Design of automatic testing framework

The skills needed to automate testing

• Understand the basic business
• Understand the technical framework of the business
• Understand functional testing
• Know a programming language
• I know the database 、 operating system
• Learn about common test frameworks
• …

What is? selenium

Selenium yes ThroughtWorks The company has a strong open source Web Functional testing tool series , Support for multiple platforms 、 Multi browser 、 Multi language to realize automatic test ,Selenium2 Will browser native API Encapsulated into WebDriver API, You can directly operate the elements in the browser page , Even operate the browser itself （ screenshots , Window size , start-up , close , Installing a plug-in , Configure certificates and so on ）, So it's like a real user is doing it .

Support multiple development languages ：ruby,python,java,perl,c# etc. , meanwhile Selenium The test runs directly in the browser , It's like a real user doing it by hand . Supported browsers include IE、Chrome and Firefox etc. .

Selenium From the previous 1.0(RC(Remote Control)) Evolved to the present Selenium2(Selenium1+WebDriver).

Selenium 2.0（ also called Selenium WebDriver） The main new feature of is the integration of WebDriver.WebDriver Used to be Selenium1（ also called Selenium RC） competitors .
Selenium RC Run... In a browser JavaScript application , and WebDriver Control the browser directly through native browser support or browser extension .

The reason for the merger , Here's why ：

• WebDriver It's solved Selenium The shortcomings of being （ such as , Bypass JS The sandbox ）;
• Selenium It's solved WebDriver The problem is （ for example Support for a wide range of browsers ）;
• Selenium The main contributors of all feel that merging projects is the best way to provide users with the best framework .

In short ：selenium
A brief introduction webdriver How it works ：

• After launching the browser ,selenium-webdriver Will bind the target browser to a specific port , The browser will be used as webdriver Of remote server.
• client ( That is, the test script ), With the help of ComandExecutor send out HTTP Request to sever End （ Communication protocol ：The WebDriver Wire Protocol, stay HTTP request Of body in , Will WebDriver Wire Under the agreement JSON Format string to tell Selenium What do we want browsers to do next ）.
• Sever End needs to rely on native browser components , conversion Web Service The command for is browser native To complete the operation .