Quality Assurance in the Presence of Variability - Intentional Perspectives on Information Systems Engineering - page 318

In the following, we will discuss these strategies in more detail and present the
benefits and challenges for each strategy.
3.1 Commonality Strategy
Quality assurance techniques that follow the commonality strategy aim at check-
ing only the common parts of a software product line. When focusing only on
common parts, the variants are typically either (1) ignored during the checking of
the reusable artifacts or (2) they are replaced by placeholders that abstract from
the variants or simulate them. As an example for the first case, an inspection of
a reusable requirements specification for a software product line could focus on
common requirements only. As an example for the second case, code fragments
of a variant could be replaced by a code fragment that implements some basic
behavior or at least guarantees that the code is structurally correct such that it will
compile.
The benefits of the commonality strategy are that early testing in domain engi-
neering is enabled and that quality assurance activities can be performed even if no
variants have been realized so far.
Techniques that follow the commonality strategy must address the following two
challenges:
1. The effort for creating placeholders has to be kept at a minimum , since the place-
holders are only used for the quality assurance purpose. Creating placeholders
usually requires development effort. Thus, the number of placeholders should be
kept as small as possible.
2. An adequate coverage of the domain artifacts has to be guaranteed . Quality
assurance activities should be planned that complement this strategy, since the
variants are not covered when following the commonality strategy.
3.2 Sample Strategy
Quality assurance techniques that follow the sample strategy aim at checking a set
of sample products of the product line. The basic steps of this strategy are typically
as follows:
1. Determine one or more sample products (defined in terms of variants that are
selected).
2. For each of the sample products:
(a) Derive product-specific artifacts by binding the variability in the domain
artifacts.
(b) Apply quality assurance techniques from the single-system development to
the derived artifacts.