System Under Test (SUT)

A System Under Test (SUT) is a System, subsystem, component, or other defined portion of a System that plays the role of the subject being evaluated by a Test.

Being under test is contextual. It does not represent an intrinsic state of the System.

The same System may participate in different Tests in different roles. For example, a System may be:

  • the System Under Test in one Test
  • a supporting System in another Test
  • a reference System in another Test
  • outside the scope of another Test

The testing role is therefore established by the applicable Test, Test Definition, or Test Item rather than by changing the intrinsic state of the System.

A System, subsystem, component, or other defined portion of a System that is the subject of evaluation within the context of a Test.

  • Object Management Group, Test Information Interchange Format (TestIF) 1.0, for the relationship between Test Items and the System Under Test
  • DIDO-TE architectural clarification of System Under Test as a contextual testing role

A Test Item may identify:

  • the complete System Under Test
  • a subsystem or component of the System Under Test
  • another entity relevant to the scope of the Test

The System Under Test is therefore distinct from the Test Item.

The System Under Test is the subject being evaluated.

The Test Item is an Information Model concept used to identify or represent an entity within the scope of the Test.

A System Under Test may have operational state, configuration, version, identity, and other characteristics independently of its testing role.

For example:

System
    Operational State = RUNNING
    Version           = 3.2.1

Test Item
    identifies        = System
    Testing Role      = System Under Test

Because the System plays the role of System Under Test, it does not require an “Under Test” state variable.

A distributed Node implementation is being evaluated for conformance with a governed communication protocol.

The Node implementation is the System Under Test for that Test.

A Test Item may identify the complete Node implementation, while additional Test Items may identify individual components or interfaces within the Node that are relevant to specific Test Cases.

In another Test, the same Node may instead participate as a supporting or reference System.


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  • public/99_annexes/annex-b-terms-and-definitions/s/system_under_test.txt
  • Last modified: 2026/09/12 17:43
  • by nick_dido