Software Testing Methodologies Dichotomies

Slicing vs Dicing

A (static) program slice is a part of a program (example: a selected set of statements) defined with respect to a given variable X (where X is a simple variable or a data vector)

A statement i: it is the set of all statements that could (potentially, under static analysis) affect the value of X at statement i - where the influence of faulty statement could result from an improper computational use or predicate use of some other variables at prior statements

If X is incorrect at statement i, it follows that the bug must be in the program slice for X with respect to i

A program dice is a part of slice in which all statements which are known to be correct, have been removed

In other words, a dice is obtained form a slice by incorporating information obtained through testing or experiment (example: debugging)

The debugger first limits its scope to those prior statements that could have caused the faulty value at statement i (the slice), and then eliminates (from further consideration) those statements that testing has shown to be correct

Debugging can be modeled as an iterative procedure in which slices are further refined by dicing, where the dicing information is obtained from ad hoc test aimed primarily at eliminating possibilities

Debugging ends when the dice has been reduced to one faulty statement

Dynamic slicing is a refinement of static slicing in which only statements on achievable paths to the statement in question are included