Interview Structure & Expectations by Level

1// Interview preparation: Common coding challenges at each level
2
3// DEVELOPER LEVEL — Write a trigger to prevent duplicate Contacts
4trigger PreventDuplicateContact on Contact (before insert, before update) {
5    Set<String> emails = new Set<String>();
6    for (Contact c : Trigger.new) {
7        if (c.Email != null) emails.add(c.Email.toLowerCase());
8    }
9    
10    if (!emails.isEmpty()) {
11        Map<String, Contact> existingMap = new Map<String, Contact>();
12        for (Contact c : [
13            SELECT Id, Email FROM Contact 
14            WHERE Email IN :emails
15        ]) {
16            existingMap.put(c.Email.toLowerCase(), c);
17        }
18        
19        for (Contact c : Trigger.new) {
20            if (c.Email != null) {
21                Contact existing = existingMap.get(c.Email.toLowerCase());
22                if (existing != null && existing.Id != c.Id) {
23                    c.addError('A contact with this email already exists.');
24                }
25            }
26        }
27    }
28}
29
30// SENIOR LEVEL — Design a flexible validation framework
31public class ValidationEngine {
32    public interface IValidator {
33        ValidationResult validate(SObject record);
34    }
35    
36    public class ValidationResult {
37        public Boolean isValid;
38        public String errorMessage;
39        public String fieldName;
40        
41        public ValidationResult(Boolean valid, String msg, String field) {
42            this.isValid = valid;
43            this.errorMessage = msg;
44            this.fieldName = field;
45        }
46    }
47    
48    private List<IValidator> validators = new List<IValidator>();
49    
50    public ValidationEngine addValidator(IValidator v) {
51        validators.add(v);
52        return this; // Fluent interface
53    }
54    
55    public List<ValidationResult> validate(SObject record) {
56        List<ValidationResult> results = new List<ValidationResult>();
57        for (IValidator v : validators) {
58            ValidationResult r = v.validate(record);
59            if (!r.isValid) results.add(r);
60        }
61        return results;
62    }
63}
64
65// Usage
66// ValidationEngine engine = new ValidationEngine()
67//     .addValidator(new EmailFormatValidator())
68//     .addValidator(new DuplicateCheckValidator())
69//     .addValidator(new RequiredFieldValidator('Phone'));
70// List<ValidationResult> errors = engine.validate(myContact);