Software Testing

Unlike physical systems, most of the defects in software are design errors. Read about the important purpose of software testing and differentiate between verification and validation and basic software testing terms. Compare and contrast the use of various testing strategies, including black-box, white-box, top-down, and bottom-up.

Test Techniques

Specification-based techniques

Equivalence partitioning

The input domain is subdivided into a collection of subsets, or equivalent classes, which are deemed equivalent according to a specified relation, and a representative set of tests (sometimes only one) is taken from each class.

Boundary-value analysis

Test cases are chosen on and near the boundaries of the input domain of variables, with the underlying rationale that many faults tend to concentrate near the extreme values of inputs. An extension of this technique is robustness testing, wherein test cases are also chosen outside the input domain of variables, to test program robustness to unexpected or erroneous inputs.

Decision table

Decision tables represent logical relationships between conditions (roughly, inputs) and actions (roughly, outputs). Test cases are systematically derived by considering every possible combination of conditions and actions. A related technique is cause-effect graphing.

Finite-state machine-based

By modeling a program as a finite state machine, tests can be selected in order to cover states and transitions on it.

Testing from formal specifications

Giving the specifications in a formal language allows for automatic derivation of functional test cases, and, at the same time, provides a reference output, an oracle, for checking test results. Methods exist for deriving test cases from model-based or algebraic specifications.

Random testing

Tests are generated purely at random, not to be confused with statistical testing from the operational profile. This form of testing falls under the heading of the specification-based entry, since at least the input domain must be known, to be able to pick random points within it.