Test data is the input that exercises tests. Strategy matters.
Approaches:
1. Apex test data factories.
apex public class TestDataFactory { public static List<Account> createAccounts(Integer n) { List<Account> accs = new List<Account>(); for (Integer i = 0; i < n; i++) { accs.add(new Account(Name='Test Account '+i)); } insert accs; return accs; } }
Used by all Apex tests. Centralised; reusable.
2. `@TestSetup`.
Class-level setup that runs once per test class. Shared data; rolled back at end.
3. Manual sandbox data for UAT.
- Real-looking data for business user testing.
- Curated; representative of production.
- Refreshed periodically.
4. Anonymised production data.
- Sensitive fields masked.
- Realistic distributions, scale.
- For performance testing, UAT.
Tools: OwnBackup Sandbox Seeding, Gearset Compare, custom scripts.
5. Synthetic data generation.
- Tools generate volume data.
- Faker library for realistic-looking values.
- For performance / load testing.
6. CSV / JSON files.
- For data-driven tests (Provar, custom).
- Same data across test runs.
Architecture:
- Factory class for unit tests.
- Anonymised data set for UAT.
- Synthetic data for performance.
Common pitfalls:
- `SeeAllData=true` tests — depend on org data; fragile.
- Inline data setup — duplicated across tests.
- Production data in sandboxes unmasked — compliance risk.
- Stale UAT data — doesn't represent current production.
Senior QA insight: test data is QA infrastructure. Invest in factories, anonymisation tools, synthetic data generation.
The senior framing: bad test data = bad tests. Garbage in, garbage out.