Executability problem

Example 1

Consider the validateIdentifier method of the Identifier program. Suppose that a given testing criterion requires the statements of this method to be executed so that statements in lines 15 and 21 must be covered by the same test case. The problem is that the statement in line 14 indicates that an invalid identifier was identified, whereas the statement in line 19 indicates the opposite. Therefore, considering the given implementation, to execute statements in lines 14 and 19 in the same execution is impossible, i.e., this testing requirement is infeasible. <bib>vincenzi-etal:2007</bib>

Example 2

Some test requirements cannot be satisfied. Suppose Tangerine jelly beans are rare, some bags may not contain any, or it may simply be too difficult to find a Tangerine bean. In this case, the flavor criterion cannot be 100% satisfied, and the maximum coverage level possible is 5/6 or 83%. It often makes sense to drop unsatisfiable test requirements from the set T R ­ or to replace them with less stringent test requirements. <bib>ammann-offutt:2008</bib>

Example 3

Dead code results in infeasible test requirements because the statements cannot be reached. <bib>ammann-offutt:2008</bib>