Write a Test Data Factory

LoanCalculationServiceTest, LoanValidationServiceTest, and LoanApplicationTriggerHandlerTest all construct Loan_Application__c-like data with similar values — a textbook case for Module 31's factory pattern, now genuinely justified by real duplication rather than a single, isolated example.

@isTest
public class LoanTestDataFactory {
    public static Loan_Application__c createApplication(Decimal amount, Decimal income, Decimal creditScore) {
        return new Loan_Application__c(
            Requested_Amount__c = amount,
            Annual_Income__c = income,
            Credit_Score__c = creditScore
        );
    }

    public static Loan_Application__c createQualifyingApplication() {
        return createApplication(10000, 50000, 720);
    }
}

createApplication takes the values that actually vary between test scenarios; createQualifyingApplication layers a sensible default on top for tests that just need any application that would pass — Module 22's constructor-parameter pattern applied to test data specifically.

@isTest
static void bulkApplicationsAllProcessCorrectly() {
    List<Loan_Application__c> applications = new List<Loan_Application__c>();
    for (Integer i = 0; i < 200; i++) {
        applications.add(LoanTestDataFactory.createQualifyingApplication());
    }

    Test.startTest();
    insert applications;
    Test.stopTest();

    // ... assertions unchanged ...
}

Same test, same assertions, same result — only the data-construction line changed, exactly the "behavior unchanged, structure clearer" outcome from every refactoring lesson since Module 12.