Data combinations

Approach Coverage based - Data
Test variety

Primarily functionality, also applicable in other test varieties

Test basis

Almost all kinds

Within functionalities single data attributes (and their equivalence classes) may influence the system behaviour, but many times combinations of data attributes are of influence on variations in the system behaviour.
Depending on the agreed depth of the test, the different coverage variations can be selected on covering data combinations:

With the coverage of data combinations a Classification tree may be used as a tool.


The following activities are carried out

  • Determine the data attributes that influence the functionality
    This does not automatically mean all the data attributes that are used by the function. It concerns the data attributes that are of influence on variations in the system behaviour. This includes the data attributes for which equivalence classes can be determined. The defined data can consist of entities, attributes or functional concepts in a general sense.
  • Determine the equivalence classes for each data attribute.
  • Determine the relationships between the data attributes
    Some data attributes are only of influence on the system behaviour under certain conditions, namely if another data attribute has a value from a specific equivalence class. That means that the possible variations of the first-mentioned data attribute must be combined with the specific value of the last-mentioned data attribute. In the example set out, such a relationship is visible between the data attributes “search criterion” and “flies to that destination”.
    The result can be illustrated in a ‘classification tree’:
  • Data attributes that logically belong together can be grouped under an overall title, such as “personal details” or “employer types”
  • Under every data attribute the equivalence classes are hung, like branches on the tree
  • Relationships between the data can be shown simply by hanging the relevant parts of the classification tree directly under the relevant equivalence class.