Salesforce Apex Quality Guardrails

Apply these checks to every Apex class, trigger, and test file you write or review.

Step 1 — Governor Limit Safety Check

Scan for these patterns before declaring any Apex file acceptable:

SOQL and DML in Loops — Automatic Fail

// ❌ NEVER — causes LimitException at scale
for (Account a : accounts) {
    List<Contact> contacts = [SELECT Id FROM Contact WHERE AccountId = :a.Id]; // SOQL in loop
    update a; // DML in loop
}

// ✅ ALWAYS — collect, then query/update once
Set<Id> accountIds = new Map<Id, Account>(accounts).keySet();
Map<Id, List<Contact>> contactsByAccount = new Map<Id, List<Contact>>();
for (Contact c : [SELECT Id, AccountId FROM Contact WHERE AccountId IN :accountIds]) {
    if (!contactsByAccount.containsKey(c.AccountId)) {
        contactsByAccount.put(c.AccountId, new List<Contact>());
    }
    contactsByAccount.get(c.AccountId).add(c);
}
update accounts; // DML once, outside the loop

Rule: if you see [SELECT or Database.query, insert, update, delete, upsert, merge inside a for loop body — stop and refactor before proceeding.

Step 2 — Sharing Model Verification

Every class must declare its sharing intent explicitly. Undeclared sharing inherits from the caller — unpredictable behaviour.

If a class does not have one of these three declarations, add it before writing anything else.

Step 3 — CRUD / FLS Enforcement

Apex code that reads or writes records on behalf of a user must verify object and field access. The platform does not enforce FLS or CRUD automatically in Apex.

// Check before querying a field
if (!Schema.sObjectType.Contact.fields.Email.isAccessible()) {
    throw new System.NoAccessException();
}

// Or use WITH USER_MODE in SOQL (API 56.0+)
List<Contact> contacts = [SELECT Id, Email FROM Contact WHERE AccountId = :accId WITH USER_MODE];

// Or use Database.query with AccessLevel
List<Contact> contacts = Database.query('SELECT Id, Email FROM Contact', AccessLevel.USER_MODE);

Rule: any Apex method callable from a UI component, REST endpoint, or @InvocableMethod must enforce CRUD/FLS. Internal service methods called only from trusted contexts may use with sharing instead.

Step 4 — SOQL Injection Prevention

// ❌ NEVER — concatenates user input into SOQL string
String soql = 'SELECT Id FROM Account WHERE Name = \'' + userInput + '\'';

// ✅ ALWAYS — bind variable
String soql = [SELECT Id FROM Account WHERE Name = :userInput];

// ✅ For dynamic SOQL with user-controlled field names — validate against a whitelist
Set<String> allowedFields = new Set<String>{'Name', 'Industry', 'AnnualRevenue'};
if (!allowedFields.contains(userInput)) {
    throw new IllegalArgumentException('Field not permitted: ' + userInput);
}

Step 5 — Modern Apex Idioms

Prefer current language features (API 62.0 / Winter '25+):

Step 6 — PNB Test Coverage Checklist

Every feature must be tested across all three paths. Missing any one of these is a quality failure:

Positive Path

• Expected input → expected output.
• Assert the exact field values, record counts, or return values — not just that no exception was thrown.

Negative Path

• Invalid input, null values, empty collections, and error conditions.
• Assert that exceptions are thrown with the correct type and message.
• Assert that no records were mutated when the operation should have failed cleanly.

Bulk Path

• Insert/update/delete 200–251 records in a single test transaction.
• Assert that all records processed correctly — no partial failures from governor limits.

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