In Apex, test classes can only contain one @testSetup method. The @testSetup annotation is used to create test data that
will be available to all test methods in the class, improving test performance by avoiding duplicate data creation.
When you define multiple @testSetup methods in the same test class, the Apex compiler will reject the code and throw a compilation
error. This happens because the Salesforce platform expects exactly one setup method per test class to maintain predictable test execution order and
data consistency.
The @testSetup method runs once before all test methods in the class, creating a clean, consistent data state. Having multiple setup
methods would create ambiguity about execution order and could lead to unpredictable test behavior.
What is the potential impact?
Multiple @testSetup methods will cause compilation errors, preventing the test class from being deployed or executed. This blocks
development progress and can prevent deployments to production environments.
