Advanced 25 min read

Design the Approval Logic

By the end of this lesson, you'll be able to:

Design a Loan_Application__c object and the approval rules it needs to enforce
Translate a lending policy into precise, testable conditions
Recognize this module's shift toward formal, automated testing from the start

Prerequisites: Module 31: "Apex Testing"

What we're building

"Given a loan application's requested amount, the applicant's annual
income, and their credit score, automatically calculate a monthly
payment and decide whether to pre-approve, refer for manual review,
or decline — following a fixed lending policy."

Modules 26, 27, and 30 each ended with a "Test the Feature" lesson doing manual Execute Anonymous verification. This module folds Module 31's toolkit in from the start — every lesson from here on either builds logic or writes real @isTest coverage for it.

The data model

Loan_Application__c
  - Requested_Amount__c (Currency)
  - Annual_Income__c (Currency)
  - Credit_Score__c (Number)
  - Interest_Rate__c (Percent, calculated)
  - Monthly_Payment__c (Currency, calculated)
  - Status__c (Picklist: Pre-Approved, Manual Review, Declined)

Module 12's "find the nouns" technique applied once more: the object holds what's asked for and what's known about the applicant; Interest_Rate__c, Monthly_Payment__c, and Status__c are all computed by Apex, not entered by hand.

Translating the lending policy into precise conditions

A real lending policy, stated precisely enough to code against directly:

Credit score 700+ and loan amount ≤ 40% of annual income → Pre-Approved.
Credit score 600-699 → always Manual Review, regardless of amount.
Credit score below 600 → Declined.

Stating these as three clean, mutually exclusive conditions now — rather than discovering ambiguity mid-implementation — is exactly Module 26's "Design the Requirement" discipline, applied to a genuinely more complex rule set.

Exercise

As a comment, classify each scenario using the policy above: (1) credit score 720, loan is 30% of income, (2) credit score 650, loan is 10% of income, (3) credit score 580.

Show hint

Apply the three rules in order.

APEX

Design the Approval Logic Quiz

1. What does this module do differently from Modules 26, 27, and 30's project structure?

It uses formal @isTest coverage from the start, rather than manual verification followed by a later testing module It doesn't use a trigger at all It has no data model design step It skips governor limit considerations entirely

My Notes

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Summary

This module builds a loan pre-approval engine — and unlike every previous project, tests it formally with @isTest from the very beginning, rather than manual verification followed by a testing lesson at the end.

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