Development with the Force.com Platform: Building Business Applications in the Cloud, Third Edition

Test Data

With the exception of users and profiles, tests do not have access to the data in the Force.com database. You can annotate a class or method with @isTest(SeeAllData=true) to make the organization’s data visible to tests, but this is not a best practice. The recommended approach is for tests to create their own temporary test data. All database modifications occurring during execution of a test method are automatically rolled back after the method is completed. Create your own test data in a setup phase before your tests are executed, and limit your assertions to that test data.