Design predicates

Design predicates are a method invented by Thomas McCabe to quantify the complexity of the integration of two units of software.

Description

Each of the four types of design predicates have an associated integration complexity rating.

For pieces of code that apply more than one design predicate, integration complexity ratings can be combined.

The sum of the integration complexity for a unit of code, plus one, is the maximum number of test cases necessary to exercise the integration fully.

Though a test engineer can typically reduce this by covering as many previously uncovered design predicates as possible with each new test.

Also, some combinations of design predicates might be logically impossible.