1.先建一个类BankAccount

package test
{
 	public class BankAccount
 	{
  		private var balance:Number=0;
  		
  		public function deposit(amount:Number):void{
   			balance=balance+amount;
   		}
  		
  		public function withdraw(amount:Number):void{
   			balance=balance-amount;
   		}
  		
  		public function getBalance():Number{
   			return balance;
   		}		
  	}
}

2.再建一个相关的测试类BankAccountTest

package test
{
  
  	import flexunit.framework.TestCase;
  	
  	public class BankAccountTest extends TestCase {
    		  		
    		/**
    		 * Test Deposit
    		 */
    		public function testDeposit():void {
   			var bankAccount:BankAccount=new BankAccount();
   			bankAccount.deposit(50);
   			assertTrue("Balance on a new account after 50 deposit is 50", bankAccount.getBalance() == 50);
   			bankAccount.deposit(25);
   			assertEquals("Balance after 50 deposit and another 25 deposit is 75", 75,bankAccount.getBalance());
      		}
    		
    		/**
    		 * Test withdraw
    		 */
    		public function testWithdraw():void {
   			var bankAccount:BankAccount=new BankAccount();
   			bankAccount.deposit(100);
   			bankAccount.withdraw(50);
   			assertTrue("Balance on a new account after 100 deposit and a 50 withdraw is 50", bankAccount.getBalance() == 50);
   			
   
      		}
    		
    	}
}

3.再建一个mxml application : flexunit.mxml

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" xmlns="*"
				xmlns:flexunit="flexunit.flexui.*"
				creationComplete="onCreationComplete()">
	
	<mx:Script>
		<![CDATA[
			import test.BankAccountTest;
			import flexunit.framework.TestSuite;
			
			// Create the test suite and run the tests
			private function onCreationComplete():void
			{
  				testRunner.test = createSuite();
  				testRunner.startTest();
  			}
			
			// Creates the test suite to run
			private function createSuite():TestSuite {
  				var testSuite:TestSuite = new TestSuite();
  				testSuite.addTestSuite(BankAccountTest);
  				return testSuite;
  			}	
		]]>
	</mx:Script>

	<!-- FlexUnit GUI Component -->
	<flexunit:TestRunnerBase id="testRunner" width="100%" height="100%" />
</mx:Application>

4. 别忘了导入测试框架FlexUnit.swc
5. 运行flexunit.mxml就可以了，你会看到2个test都通过测试了。

备注：工程文件上传半天不成功，不过没关系，新建一个工程，新建上面3个文件，把FlexUnit.swc考进libs文件夹就可以运行了