Real-World Scenario

You inherit an org where:

● Triggers contain large logic blocks
● Queries are duplicated
● Code is hard to test

Business now asks for:

● New rules
● Performance improvements
● Integration changes

Directly modifying existing logic is risky.

Safe refactoring strategy:

● Add new structure first
● Move logic gradually
● Validate using tests and feature flags

What Is Refactoring?

Refactoring means:

Improving code structure without changing system behavior.

It focuses on:

● Readability
● Maintainability
● Scalability

Not on adding new features.

Step-by-Step Safe Refactoring Strategy

◆ Step 1 – Protect Behavior with Tests

Before changing code:

● Identify key business flows
● Add or strengthen test coverage
● Cover both success and failure scenarios

Tests act as your safety net.

◆ Step 2 – Extract Logic into Services

Before

trigger AccountTrigger on Account (before update) {
    for(Account a : Trigger.new){
        if(a.Type == 'Customer'){
            a.Priority__c = 'High';
        }
    }
}

After

Trigger:

trigger AccountTrigger on Account (before update) {
    AccountService.applyPriorityRules(Trigger.new);
}

Service:

public class AccountService {
    public static void applyPriorityRules(List<Account> accs){
        for(Account a : accs){
            if(a.Type == 'Customer'){
                a.Priority__c = 'High';
            }
        }
    }
}

Behavior remains same, structure improves.

◆ Step 3 – Introduce Selector Layer

Move SOQL gradually into selectors.

Before:

List<Account> accs = [SELECT Id FROM Account WHERE Type='Customer'];

After:

List<Account> accs = AccountSelector.getCustomers();

Now future query changes happen in one place.

◆ Step 4 – Add Feature Flags for Risky Changes

If new logic is risky:

if(FeatureFlagService.isEnabled('New_Priority_Logic')) {
    applyNewLogic();
} else {
    applyOldLogic();
}

This allows:

● Production deployment without activation
● Instant rollback via metadata

◆ Step 5 – Replace Old Logic Gradually

Once new structure is stable:

● Remove legacy methods
● Clean dead code
● Simplify services

Never refactor everything in one deployment.

Refactoring Anti-Patterns to Avoid

● Large refactor + new features together
● Removing old logic without test coverage
● Big bang architecture rewrites
● Ignoring production data volumes

Always separate:

● Structural improvement
● Business changes

Tools That Help Safe Refactoring

● Debug logs
● Code coverage reports
● Static code analysis
● Feature flags
● Small incremental deployments

Refactoring is a process, not a one-time event.

Testing During Refactoring

Best approach:

● Keep old tests passing
● Add new tests for new structure
● Validate both before and after deployment

If tests fail, refactoring is not safe yet.

Best Practices

● Refactor in small steps
● Never refactor without tests
● Use Service and Selector layers
● Use feature flags for high-risk changes
● Communicate with business before major changes

Safe refactoring builds trust between developers and business users.

Conclusion

In this blog, you learned how to refactor Apex code safely without breaking production systems.

Refactoring is how good systems become great systems.

Improve boldly, deploy safely, and let quality drive every release. 🚀

Apex Beginner to Advance

Refactoring Apex Without Breaking Production