Section 19.4. System Test


19.4. System Test

Automated, FunctionalTest, JavaScript, PerformanceTest, Regression, Robot, UnitTest, TDD, Test

Figure 19-5. System Test


19.4.1. Developer Story

Devi has completed the first cut of a new Ajax App and wants to build an automated test of the whole thing. With the help of a testing application, she records a typical usage so it can be played back later. The software takes note of the final state, which will be used for verification during automated playback.

19.4.2. Problem

How can you test an entire Ajax App?

19.4.3. Solution

Build automated tests to simulate user behavior and verify the results. A System Test exercises a complete system in much the same way as a user would. The most common category of system test is a functional testverifying the functionalitybut system testing also encompass qualities such as performance and robustness. While they are often conducted manually, with users clicking and mousing around, it's highly preferable to automate as much as possible in order to promote continuous integration.

Automated system tests remain somewhat difficult, but tools are improving. They can be broadly categorized as follows:


Browser Controller (Figure 19-6)

A specialized, "robot"-style testing tool will fire up the browser, then use the underlying operating system's API to create the effect of a user interacting with the browser. Several commercial controllers are able to record user actions for later playback.

Figure 19-6. Browser Controller


Embedded Browser Script (Figure 19-7)

Run the application in a standard browser and embed a Browser-Side Test on the page. The test can use some JavaScript trickery to simulate user activity. Don't let the browser aspect put you off, because it's feasible to have a continuous integration tool like Ant coordinate Browser-Side Tests, as pointed out earlier in this chapter.

Figure 19-7. Embedded Browser Script


Browser Simulation (Figure 19-8)

The application is executed by a model of a real browser. Typically, the simulation pulls a page from a URL somewhere and builds up a DOM to represent it. The DOM can then be manipulated; e.g. the simulation allows a button click operation to occur or a form to be submitted. While several frameworks like this exist, the important issue for Ajax developers is how well they simulate JavaScript. JavaScript interpreters are implemented in several languages, so it's possible for Browser Simulations to incorporate them in order to simulate a realistic Ajax interaction.

Figure 19-8. Browser Simulation


The first two approaches involve a real browser, which is a more realistic test, but it does imply that the test must run on a machine capable of launching the browser, or of somehow controlling it remotely.

System Tests require not just automation of user behavior, but also automation of result verification. As with other tests, results can be verified with a combination of assertions against the DOM and against server-side state.

19.4.4. Tool Support

19.4.4.1. GhostTrain

Scriptaculous's GhostTrain (http://wiki.script.aculo.us/scriptaculous/show/GhostTrain) is an Embedded Browser Script with recording capability. When you start the recording mode, a Scriptaculous test case begins to fill up inside the div. Each mouse and key action becomes a new line of the test case. Later on, you can add your own assertions about the application state. GhostTrain is a very promising work in progress.

19.4.4.2. Watir

Watir (http://wtr.rubyforge.org) follows the Browser Controller approach, enabling a Ruby programmer to script browser behavior and interrogate the DOM at any stage. You can easily integrate Watir commands into a standard test casefor example:

   ie = Watir::IE.start("http://ajaxpatterns.org")   ie.button(:name, "Search").click 

Watir is IE-specific right now.

19.4.4.3. Selenium

Selenium (http://selenium.thoughtworks.com/) is an open source tool by Thoughtworks developers, an Embedded Browser Script framework that works in IE, Mozilla, Firefox, and Safari. A JavaScript Selenium component is embedded inside the browser application under test, and it communicates with a server-side component. Interesting, there's flexibility on the location of the server-side component. It can be placed in the web server, to provide a quick summary in the web page being developed. Alternatively, it can be run as a separate server, where the server controls the browser (like a Browser Controller would), and the embedded browser component merely transmits server commands to the application.

19.4.4.4. HTTPUnit

HTTPUnit (http://httpunit.sourceforge.net/index.html) is an open source Java testing framework, built on JUnit, and specifically designed for testing web apps. It works as a Browser Simulator, converting an HTML page into a Java HTMLPage object that wraps a Java DOM model of the original HTML. HTTPUnit simulates JavaScript by delegating to the Rhino JavaScript engine, although support is incomplete.

19.4.4.5. DojoToolkit

Dojo Toolkit (http://dojotoolkit.org/docs/compressor_system.html) is a Java-based Browser Simulator that uses Rhino to let you run tests from an Ant task. Given the project's momentum and focus on Ajax, it's likely to evolve into a very solid product.

19.4.5. Code Example: Using Scriptaculous GhostTrain

The Ajax Patterns Reader (http://ajaxify.com/run/reader/logging/realService/ghost/) is refactored here to include Scriptaculous's GhostTrain (http://wiki.script.aculo.us/scriptaculous/show/GhostTrain), discussed earlier. You can hit Escape anywhere in the document to open it up, and then use the buttons to record a test case, which can then be played back (Figure 19-9).

Figure 19-9. GhostTrain


To hook up GhostTrain, the Scriptaculous library files must be included (quite a lot to download, but keep in mind they don't need to be included in production):

   <script type="text/javascript" src="/books/2/755/1/html/2//run/Lib/js/sc/prototype.js"></script>   <script type="text/javascript" src="/books/2/755/1/html/2//run/Lib/js/sc/controls.js"></script>   <script type="text/javascript" src="/books/2/755/1/html/2//run/Lib/js/sc/effects.js"></script>   <script type="text/javascript" src="/books/2/755/1/html/2/unittest.js"></script>   <script type="text/javascript" src="/books/2/755/1/html/2/ghosttrain.js"></script> 

The only other requirement is to register the GhostTrain object as a keypress handler. The handler will take care of any other initialization:

   window.onload = function( ) {     Event.observe(document, 'keypress', GhostTrain.intercept, true);     ...   } 

19.4.6. Related Patterns

19.4.6.1. Browser-Side Test

System Test frameworks that work as Embedded Browser Scripts are a form of Browser-Side Tests (see earlier).

19.4.6.2. Simulation Service

For integration tests, you can configure the server to run against a Simulation Service (see earlier). That way, you'll have tight control over server behavior, ensuring the final state is deterministic.

19.4.7. Want to Know More?

  • A Summary of Functional Testing Frameworks (http://www.softwareqatest.com/qatweb1.html#FUNC).




Ajax Design Patterns
Ajax Design Patterns
ISBN: 0596101805
EAN: 2147483647
Year: 2007
Pages: 169

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