Friday, April 9, 2010

Interacting With a Web Page

You will notice we've chosen to name the variable name ie used in Watir test scripts for the Internet Explorer browser. You could call it whatever you wish, but we use ie for ease of use. This variable tells the Watir library to exercise test scripts against an instance of the Internet Explorer web browser.
In Ruby, think of programming in terms of objects and messages. Watir was also developed with objects and messages in mind. If you think of the ie variable as an object, you can send messages to it. Think of objects as nouns. When you start up Internet Explorer, the operating system starts the program which creates an instance of the Internet Explorer web browser. You refer to this Internet Explorer browser instance as a thing. If you send a message to that object, it will respond to that message if it recognizes it.
Think of the messages as verbs. In Ruby, you send a message to an object by separating the object you are calling from the message you are sending to it with a dot. For example:
would tell the object dog that it must bark.
This isn't very specific though. What dog should bark? In the Watir world, you could identify the test area to be our yard. Like ie, treat it as an object with attributes containing other objects with attributes. For example, in our yard, there are two dogs: Heidi and Megabyte. Each of these dog objects have attributes that identify them. They have names, breeds, shapes and sizes and colors. To be more specific, and interacting with them the Watir way, you could send the message bark to the dog Heidi like this:, "Heidi").bark
This says in Watir syntax: in the yard, identify the dog Heidi by her name attribute, and send her the bark message. The expected outcome would be Heidi responding to the message by barking.
When you develop test scripts with Watir, you interact with objects on a web page by sending them messages. Like the yard example, the Internet Explorer browser itself contains objects. You can access these objects within an Internet Explorer browser instance by identifying them by different attributes. Just like in the dog example, above, you must be very specific when you send messages to objects on a web page. You must also be able to identify objects on a web page by using a variety of different attributes due to the diversity in how tags are declared by different application developers. With Watir, identify objects and send them messages by using the dot notation. For example:
narrows down the type of object to send a message to.
ie.button(:value, "Click Me").click
identifies the object on the page as a button within the instance of Internet Explorer (ie) that has the value attribute (caption) Click Me. When you send the message (the verb) click, Watir interprets and tells Internet Explorer to click.

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