Salesforce Developer Apex Soap Callout

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// Salesforce - Developer - SOAP - Callout:

In addition to REST callouts, Apex can also make callouts to SOAP web services 
using XML.  WSDL2Apex automatically generates Apex classes from a WSDL document. 
You download the web service’s WSDL file, and then you upload the WSDL and 
WSDL2Apex generates the Apex classes for you. The Apex classes construct the 
SOAP XML, transmit the data, and parse the response XML into Apex objects. 
Instead of developing the logic to construct and parse the XML of the web 
service messages, let the Apex classes generated by WSDL2Apex internally handle 
all that overhead.

Use outbound messaging to handle integration solutions when possible. Use 
callouts to third-party web services only when necessary.

The first thing we need to do is download the WSDL file to generate the Apex 
classes.

To Generate an Apex Class from the WSDL:

1. From Setup, enter Apex Classes in the Quick Find box, then click Apex Classes.

2. Click Generate from WSDL.

3. Click Choose File and select the downloaded calculator.xml file.

4. Click Parse WSDL. The application generates a default class name for each 
   namespace in the WSDL document and reports any errors.

   WSDL2Apex parsing is a notoriously fickle beast. The parsing process can fail 
   for several reasons, such as an unsupported type, multiple bindings, or 
   unknown elements. Unfortunately, you could be forced to manually code the 
   Apex classes that call the web service or use HTTP.

5. Click Generate Apex code. The final page of the wizard shows the generated 
   classes, along with any errors. The page also provides a link to view 
   successfully generated code.

The generated Apex classes include stub and type classes for calling the 
third-party web service represented by the WSDL document. These classes allow 
you to call the external web service from Apex. For each generated class, a 
second class is created with the same name and the prefix Async. The 
calculatorServices class is for synchronous callouts. The 
AsyncCalculatorServices class is for asynchronous callouts.

To Execute the Callout:

1. Open the Developer Console under Your Name or the quick access menu 
   (Setup gear icon).

2. In the Developer Console, select Debug | Open Execute Anonymous Window.

3. Delete all existing code and insert the following snippet.

calculatorServices.CalculatorImplPort calculator = new  calculatorServices.CalculatorImplPort();
Double x = 1.0;
Double y = 2.0;
Double result = calculator.doAdd(x,y);
System.debug(result);

4. Select Open Log, and then click Execute.

5. After the debug log opens, click Debug Only to view the output of the 
   System.debug statements. The log should display 3.0.

// Salesforce - Developer - SOAP - Callout - Test using WebServiceMock:

To prevent tests from failing and to increase code coverage, Apex provides a 
built-in WebServiceMock interface and the Test.setMock method. You can use this 
interface to receive fake responses in a test method, thereby providing the 
necessary test coverage.

When you create an Apex class from a WSDL, the methods in the autogenerated 
class call WebServiceCallout.invoke, which performs the callout to the external 
service. When testing these methods, you can instruct the Apex runtime to 
generate a fake response whenever WebServiceCallout.invoke is called. To do so, 
implement the WebServiceMock interface and specify a fake response for the 
testing runtime to send.

Instruct the Apex runtime to send this fake response by calling Test.setMock in 
your test method. For the first argument, pass WebServiceMock.class. For the 
second argument, pass a new instance of your WebServiceMock interface 
implementation.

Test.setMock(WebServiceMock.class, new MyWebServiceMockImpl());

In this example, you create the class that makes the callout, a mock 
implementation for testing, and the test class itself.

1. In the Developer Console, select File | New | Apex Class.

2. For the class name, enter AwesomeCalculator and then click OK.

3. Replace autogenerated code with the following class definition.

public class AwesomeCalculator {
    public static Double add(Double x, Double y) {
        calculatorServices.CalculatorImplPort calculator = 
            new calculatorServices.CalculatorImplPort();
        return calculator.doAdd(x,y);
    }
}

4. Press CTRL+S to save.

   Create your mock implementation to fake the callout during testing. Your 
   implementation of WebServiceMock calls the doInvoke method, which returns the 
   response you specify for testing. Most of this code is boilerplate. 

5. In the Developer Console, select File | New | Apex Class.

6. For the class name, enter CalculatorCalloutMock and then click OK.

7. Replace the autogenerated code with the following class definition.

@isTest
global class CalculatorCalloutMock implements WebServiceMock {
   global void doInvoke(
           Object stub,
           Object request,
           Map<String, Object> response,
           String endpoint,
           String soapAction,
           String requestName,
           String responseNS,
           String responseName,
           String responseType) {
        // start - specify the response you want to send
        calculatorServices.doAddResponse response_x = 
            new calculatorServices.doAddResponse();
        response_x.return_x = 3.0;
        // end
        response.put('response_x', response_x); 
   }
}

8. Press CTRL+S to save.

   Lastly, your test method needs to instruct the Apex runtime to send the fake 
   response by calling Test.setMock before making the callout in the 
   AwesomeCalculator class. Like any other test method, we assert that the 
   correct result from our mock response was received.

9. In the Developer Console, select File | New | Apex Class.

10. For the class name, enter AwesomeCalculatorTest and then click OK.

11. Replace the autogenerated code with the following class definition.

@isTest
private class AwesomeCalculatorTest {
    @isTest static void testCallout() {              
        // This causes a fake response to be generated
        Test.setMock(WebServiceMock.class, new CalculatorCalloutMock());
        // Call the method that invokes a callout
        Double x = 1.0;
        Double y = 2.0;
        Double result = AwesomeCalculator.add(x, y);
        // Verify that a fake result is returned
        System.assertEquals(3.0, result); 
    }
}

12. Press CTRL+S to save.

13. To run the test, select Test | Run All.