Writing Test Classes for Invocable and @Future Apex Methods

Writing Test Classes for Invocable and @Future Apex Methods

On January 26, 2025, Posted by , In Apex, With Comments Off on Writing Test Classes for Invocable and @Future Apex Methods
Writing Test Classes for Invocable and @Future Apex Methods

Question

How Can I Write Test Classes for an Invocable Apex Class and an @Future Callout Class?

I am new to Apex and eager to learn. I have two classes that work as intended, but I am struggling to create test classes for them since I have never written test classes before. Writing test classes for Invocable and @Future Apex methods can be particularly challenging. Knowing how to write test classes for Invocable and @Future Apex methods can greatly improve your debugging efficiency and code quality.

  1. Invocable Apex Class: This class is triggered by a Process Builder when a Lead record meets specific criteria. It sends lead details, such as ID, Email, First Name, and Last Name, to another class.
  2. @Future Apex Class: This class performs a POST HTTP callout to an external system using the lead data. It receives an ID in the API response, which it then updates on the Lead record.

I need help understanding how to write effective test classes to validate these functionalities.

Answer

Testing an Invocable Apex class and an @Future method that performs an HTTP callout involves creating mock data, simulating the HTTP response, and validating that the logic behaves as expected. Here’s the breakdown of the scenario and the solution:

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You have two classes:

  1. Invocable Apex Class: This class is called by a Process Builder or Flow. It receives a list of leads, extracts data, and invokes an @Future method for a callout.
  2. @Future Callout Class: This class makes a POST HTTP callout to an external system using the lead data. The response includes an ID, which is then updated on the lead record.

To test these classes, you need to handle two challenges:

  • Simulating the HTTP callout using a HttpCalloutMock class.
  • Writing a test class to enqueue the future method and validate the results.

Here’s how you can achieve this when writing test classes for Invocable and @Future Apex methods:

Test Class for the Invocable and @Future Callout Classes

The test class uses mock data and an HTTP callout mock to simulate external API behavior. It verifies whether the lead record is updated correctly after the callout.

@isTest
class MakeCalloutTest {
    // A simple HTTP mock class to simulate an external API response
    class EchoHttpMock implements HttpCalloutMock {
        HttpResponse response;
        
        EchoHttpMock(HttpResponse res) {
            response = res;
        }
        
        public HttpResponse respond(HttpRequest req) {
            return response;
        }
    }

    @isTest
    static void testInvocableAndFutureCallout() {
        // Step 1: Create mock lead data
        List<Lead> leads = new List<Lead>{
            new Lead(LastName = 'Test', Company = 'Test Company')
        };
        insert leads;
        
        // Step 2: Simulate the HTTP callout response
        HttpResponse mockResponse = new HttpResponse();
        mockResponse.setBody('<?xml version="1.0" encoding="utf-8"?><root U_Id="12345"></root>');
        mockResponse.setStatusCode(200);
        Test.setMock(HttpCalloutMock.class, new EchoHttpMock(mockResponse));

        // Step 3: Start test and invoke the invocable method
        Test.startTest();
        MakeCallout.invokeleadcallout(leads);
        Test.stopTest();

        // Step 4: Validate that the lead was updated with the correct ID
        Lead updatedLead = [SELECT Id__c FROM Lead WHERE Id = :leads[0].Id];
        System.assertEquals('12345', updatedLead.Id__c, 'The ID__c field was not updated correctly.');
    }

    @isTest
    static void testCalloutExceptionHandling() {
        // Step 1: Simulate an error response for the callout
        HttpResponse errorResponse = new HttpResponse();
        errorResponse.setStatusCode(500);
        errorResponse.setBody('{"error": "Internal Server Error"}');
        Test.setMock(HttpCalloutMock.class, new EchoHttpMock(errorResponse));

        // Step 2: Create mock lead data
        List<Lead> leads = new List<Lead>{
            new Lead(LastName = 'ErrorTest', Company = 'Error Test Company')
        };
        insert leads;

        // Step 3: Start test and invoke the invocable method
        Test.startTest();
        MakeCallout.invokeleadcallout(leads);
        Test.stopTest();

        // Step 4: Validate that no updates were made to the lead
        Lead unchangedLead = [SELECT Id__c FROM Lead WHERE Id = :leads[0].Id];
        System.assertNull(unchangedLead.Id__c, 'The ID__c field should not be updated for a failed callout.');
    }
}

Explanation of the Test Class

  1. Mocking the HTTP Response: The EchoHttpMock class implements the HttpCalloutMock interface, allowing you to simulate API responses for both success and error cases. This is crucial when writing test classes for Invocable and @Future Apex methods.
  2. Creating Test Data: The test class creates and inserts lead records to work with during the test execution.
  3. Simulating the Callout: The Test.setMock method specifies the mocked HTTP response for the callout.
  4. Testing Logic: The test cases invoke the invocable method, enqueue the future method, and validate the final state of the lead records.
  5. Handling Exceptions: A separate test ensures that the catch block in the @future method handles errors correctly and does not update lead records when the callout fails.

This approach covers both the success and error scenarios, ensuring that your classes are thoroughly tested.

See also: Salesforce Identity Management Interview Questions

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