CAT - Customer Acceptance Testing

Acceptance Testing is often seen as marking the change in a system’s ownership from the developers of the system to those who will use the system.It is a distinct phase of testing prior to final sign-off and delivery of a system to the customers or business users.The responsibility for acceptance testing may reside with the customer (CAT - Customer Acceptance Testing) and/or end users (UAT) themselves.
The primary objectives of preceding test phases (unit, integration and systems testing) are those of defect identification and ensuring that each step in the process of building the software delivers working products (verification).
The objective of Acceptance Testing is to give confidence that the software being developed, or changed, satisfies the specified requirements, meets customer/user expectations and is fit for business purpose (validation). Unlike the other test phases, an objective of acceptance testing is not to actively look for faults. The expectation should be that the preceding stages of testing have identified and resolved software faults and that the system is ready for operational use.
Clear entry criteria may need to be put in place to ensure that the expectation of a system being ‘production ready’ has been met.This is an opportunity to review the effectiveness, completeness and outcome of previous test phases and to declare any known problems that remain prior to acceptance test commencing.
As a testing phase with it’s own objectives, acceptance should not seek to duplicate other test phases.However, it may repeat previously run test scenarios to provide confidence that preceding test phases have been completed as appropriate. Those responsible for acceptance testing should dictate the objectives and coverage of the test phase. In doing so they are likely to consider the following:

• Have the acceptance test conditions been demonstrated?
  
• Do the test conditions model realistic business scenarios?
  
• Is there appropriate coverage of each business function?
• Is there appropriate coverage of system reports and screen?
  
• Is there appropriate coverage of application menu options?
• Are updated training materials and system documentation subject to test?

It is important to minimise the number of changes taking place to the system during the acceptance test phase.The cost of reworking, to change software or system operation, at this stage of development is high.Implemented changes may invalidate testing that has been already conducted and require greater levels of regression testing to be carried out.
Where faults are uncovered during acceptance, temporary fixes should first be investigated before attempting to make changes to the software.However, it may be necessary to agree the correction of high severity/priority problems and to defer/timetable the correction of others before acceptance can occur.
In order to minimise the risk of software faults and system changes, acceptance should not just start at software delivery. It needs to be a function of the earliest design and development stages. Early involvement of users in the system requirements and design stages can minimise the risk of gaps and misinterpretations occurring in end system functionality.The benefits reaped at later stages can be the avoidance of re-work and the reduced cost of system delivery.

Acceptance testing definitions

From Search CIO

Wikipedia describes acceptance testing as:

"... is black-box testing performed on a system (e.g. software, lots of manufactured mechanical parts, or batches of chemical products) prior to its delivery...

"In most environments, acceptance testing by the system provider is distinguished from acceptance testing by the customer (the user or client) prior to accepting transfer of ownership...

"A principal purpose of acceptance testing is that, once completed successfully, and provided certain additional (contractually agreed) acceptance criteria are met, the sponsors will then sign off on the system as satisfying the contract (previously agreed between sponsor and manufacturer), and deliver final payment."

This is consistent with the definition Cem Kaner uses throughout his books, courses, articles and talks, which collectively are some of the most highly referenced software testing material in the industry. The following definition is from his Black Box Software Testing course:

"Acceptance testing is done to check whether the customer should pay for the product. Usually acceptance testing is done as black box testing."

Another extremely well-referenced source of software testing terms is the International Software Testing Qualifications Board (ISTQB) Standard glossary of terms. Below is the definition from Version 1.3 (dd. May, 31, 2007):

"Formal testing with respect to user needs, requirements, and business processes conducted to determine whether or not a system satisfies the acceptance criteria and to enable the user, customers or other authorised entity to determine whether or not to accept the system."

I've chosen those three references because I've found that if Wikipedia, Cem Kaner and the ISTQB are on the same page related to a term or the definition of a concept, then the testing community at large will tend to use those terms in a manner that is consistent with these resources. Acceptance testing, however, is an exception.

There are several key points on which these definitions/descriptions agree:

1. In each case, acceptance testing is done to determine whether the application or product is acceptable to someone or some organisation and/or if the person or organisation should pay for the application or product AS IS.
2. "Finding defects" is not so much as mentioned in any of those definitions/descriptions, but each implies that defects jeopardise whether the application or product becomes "accepted."
3. Pre-determined, explicitly stated, mutually agreed-upon criteria (between the creator of the application or product and the person or group that is paying for or otherwise commissioned the software) are the basis for non-acceptance.
   
   Wikipedia refers to this agreement as a contract, and identifies that non-compliance with the terms of the contract as a reason for non-payment. And Kaner references the contract through the question of whether the customer should pay for the product.
   
   The ISTQB does not directly refer to either contract or payment but certainly implies the existence of a contract (an agreement between two or more parties for the doing or not doing of something specified).

User Acceptance Test UAT