As mentioned earlier, Acceptance Tests are a special category of test used to verify that the:
Acceptance and Sign-off
Project fulfils the customer's requirements.
Customer accepts the project.
They should be defined by the customer and project manager. They have particular significance as they are often related to the final invoicing.
For this reason they must be:
Defined as early as possible.
Updated whenever necessary.
Any changes must be formally accepted and signed by both parties (partner and the customer).