Categories are assigned to variable occurrences in the component, where the category identifies the definition or the use of the variable at that point. Definitions are variable occurrences where a variable is given a new value, and uses are variable occurrences where a variable is not given a new value, although uses can be further distinguished as either data definition P-uses or data definition C-uses. Data definition P-uses occur in the predicate portion of a decision statement such as while .. do, if .. then .. else, etc. Data definition C-uses are all others, including variable occurrences in the right hand side of an assignment statement, or an output statement.
The control flow model for the component is derived and the location and category of variable occurrences on it identified.Test cases shall be designed to execute control flow paths between definitions and uses of variables in the component.
Each test case shall include:- the input(s) to the component;
- locations of relevant variable definition and use pair(s);
- control flow subpath(s) to be exercised;
- the expected outcome of the test case.