Hi Ken,

To simulate your callout in your test method you should first of all, adjust your apex class (where you execute the callout) taking care of this:

1. Create a public boolean variable in your class that works like a flag, let this class being able to know when to run the callout and when not.

2. Create a public "Response" variable to set a simulated response.

3. Include logic to your class that works according to the flag of point 1.

Later, in your testMethod invoke the RESPONSE (of your apex class) and set the kind of response you need to test, set the flag value and call the apex class method that executes the callout.

See the following example:

Apex Class (the one that runs the callout)

global class SyncClass_snc {
	public static boolean blnIsTest = false;			// Controls when a callout is invoked from a TestClass to avoid restriction 
	public static MyCreatedFromWSDLClass.RESPONSE MyResponseTest; // Loads the object related to the response from the callout
	
	public static void SendInfo(string strFirstName, string strLastName){
		try{
			// Here comes your custom code...
			
			// Builds the object to send.
			MyCreatedFromWSDLClass.ServiceSoap11 MyService = new MyCreatedFromWSDLClass.ServiceSoap11(); 
			MyCreatedFromWSDLClass.BASIC_DATA BasicDataInfo = new MyCreatedFromWSDLClass.BASIC_DATA();
			MyCreatedFromWSDLClass.RESPONSE MyRealResponse = new MyCreatedFromWSDLClass.RESPONSE();
			
			// Prepares data
			BasicDataInfo.FirstName = strFirstName;
			BasicDataInfo.LastName = strLastName;
			
			if(!blnIsTest){ // If it is not a test, runs the real callout
				MyRealResponse = MyService.RunCallout(BasicDataInfo);
			}else{
				MyRealResponse = MyResponseTest; // Passes by value the callout simulated response
			}
			// Here comes the logic that processes the response...
			
		}catch(System.Exception e){
			system.debug('***** The following Error has been catched: Type: '+e.getTypeName()+'. Message: '+e.getMessage();
		}
	}
}

Apex TestMethod

@isTest
private class SyncTest_tst {
    
	static testMethod void test1() {
		// Sets the flag to TRUE to avoid real callouts
    	SyncClass_snc.blnIsTest = true;
		
		// Sets the custom Response
		SyncClass_snc.MyResponseTest = = new MyCreatedFromWSDLClass.RESPONSE();
		SyncClass_snc.MyResponseTest.SUCCESS_OPERATION = true; // Sets an affirmative response
		
		test.startTest();
			// Calls the method that runs the callout
			SyncClass_snc.SendInfo('John', 'Smith');
			
			// Now, tries with a controlled error
			SyncClass_snc.MyResponseTest = = new MyCreatedFromWSDLClass.RESPONSE();
			SyncClass_snc.MyResponseTest.SUCCESS_OPERATION = false; // Sets an negative response
			
			// Calls the method that runs the callout
			SyncClass_snc.SendInfo('Sarah', 'Brookes');
			
		test.stopTest();
	}
}

I hope this info and example help you.

Regards,

Wilmer