Considerations for the IsTest(SeeAllData=true) Annotation

• If a test class is defined with the isTest(SeeAllData=true) annotation, this annotation applies to all its test
methods whether the test methods are defined with the @isTest annotation or the testmethod keyword.
• The isTest(SeeAllData=true) annotation is used to open up data access when applied at the class or method level. However, using isTest(SeeAllData=false) on a method doesn’t restrict organization data access for that method if the containing class has already been defined with the isTest(SeeAllData=true) annotation. In this case, the method will still have access to all the data in the organization.