Thursday 12 May 2016

Selenium Core Extensions


To understand extensions, lets first understand the three pillars of selenium IDE
  1. Action: What operation you are performing on UI Screen
  2. Assessors/Assertion: What verification you do on data you get from UI
  1. Locator Strategy: How can we find the element in UI.
Now, Selenium IDE has a very mature library with plenty of Actions, Assertion/Assessors and Locator Strategies.
But sometimes we need to add some more functionality to it for our project requirements. In that situation, we can expand this library by adding our custom extensions. These custom extensions are called 'User Extension'.
For example, we need an Action which can convert the text to upper case before filling it in a web element. You cannot find this Action in the default Action library. In such case you can create your own 'User Extension'. In this tutorial , we will learn how to create user extension to convert Text to Upper Case

Requirement to create Selenium user extension:

To create user extension for Selenium IDE we need to know the basic concept of JavaScript and Java Script prototype object concept.
To create your own user extension you need to create Java script methods and add them to the selenium object prototype and PageBot object prototype.

How Selenium IDE recognizes User Extension?

After adding of User Extension to Selenium IDE when we start selenium IDE, all of these extensions in javascript prototype get loaded and Selenium IDE recognizes them by their name.

How to Create User Extension

Step 1) Action- all actions are started by "do", i.e. if the action is for upper case text than its name will be doTextUpperCase. When we add this action method in Selenium IDE, Selenium IDE will itself create a wait method for this action. So in this case when we create doTextUpperCase action, Selenium IDE will create a corresponding wait function as TextUpperCaseAndWait. It can accept two parameters
Example: Upper Case Text Action
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Selenium.prototype.doTextUpperCase = function(locator, text) {
     // Here findElement is itself capable to handle all type of locator(xpath,css,name,id,className), We just need to pass the locator text
     var element = this.page().findElement(locator);
       
     // Create the text to type
     text = text.toUpperCase();
       
     // Replace the element text with the new text
     this.page().replaceText(element, text);
    };
Step 2) Assessors/Assertion- All assessors registered in selenium object prototype will be prefixed
by "get" or "is" Ex. getValueFromCompoundTable , isValueFromCompoundTable .It can accept two parameters, one for target and other for value field in test case.
For each Assessor there will be corresponding verification functions prefixed by "verify", "assert" and the wait function prefix by "waitFor"
    
Example: For Upper Case Text assessors
    
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Selenium.prototype.assertTextUpperCase = function(locator, text) {
     // All locator-strategies are automatically handled by "findElement"
     var element = this.page().findElement(locator);
       
     // Create the text to verify
     text = text.toUpperCase();
       
     // Get the actual element value
     var actualValue = element.value;
     
     // Make sure the actual value matches the expected
     Assert.matches(expectedValue, actualValue);
    };
     
    Selenium.prototype.isTextEqual = function(locator, text) {
     return this.getText(locator).value===text;
    };
     
    Selenium.prototype.getTextValue = function(locator, text) {
     return this.getText(locator).value;
    };
Step 3) Locator strategy- If we wish to create our own function to locate an element then
    we need to extend PageBot prototype with a function with prefix "locateElementBy".
    It will take two parameters, first will be the locator string and second will be the document
    where it needs to be search.
    
Example: For Upper Case Text Locator
    
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// The "inDocument" is a document you are searching.
    PageBot.prototype.locateElementByUpperCase = function(text, inDocument) {
     // Create the text to search for
     var expectedValue = text.toUpperCase();
       
     // Loop through all elements, looking for ones that have
     // a value === our expected value
     var allElements = inDocument.getElementsByTagName("*");
// This star '*' is a kind of regular expression it will go through every element (in HTML DOM every element surely have a tag name like<body>,<a>,<h1>,<table>,<tr>,<td> etc. ). Here our motive is to find an element which matched with the Upper Case text we have passed so we will search it with all elements and when we get match we will have the correct web element.
     for (var i = 0; i < allElements.length; i++) {
     var testElement = allElements[i];
     if (testElement.innerHTML && testElement.innerHTML === expectedValue) {
     return testElement;
     }
     }
     return null;
    };

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