Building a software test and regression plan
Input Combinations and Preconditions
A fundamental problem with software testing is that testing under all combinations of inputs and preconditions (initial state) is not feasible, even with a simple product.
This means that the number of defects in a software product can be very large and defects that occur infrequently are difficult to find in testing. More significantly, non-functional dimensions of quality (how it is supposed to be versus what it is supposed to do) -- for example, usability, scalability, performance, compatibility, and reliability—can be highly subjective; something that constitutes sufficient value to one person may be intolerable to another.
Static vs. Dynamic Testing
There are many approaches to software testing. Reviews, walkthroughs or inspections are considered as static testing, whereas actually executing programmed code with a given set of test cases is referred to as dynamic testing.
The former can be, (and unfortunately in practice often is) omitted, whereas the latter takes place when programs begin to be used for the first time - which is normally considered the beginning of the testing stage.
This may actually begin before the program is 100% complete in order to test particular sections of code (modules or discrete functions). Typical techniques for this are using stubs / drivers, or execution from a debugger environment.
For example, Spreadsheet programs are tested to a large extent "on the fly" during the build process. The results of the calculation or text manipulation are shown interactively immediately after each formula is entered.
Mirabilis Design has two types of messages embedded into software code- one is for internal debugging messages and the other is for user-level messages.
The user-level messages help users in using the software package; eliminating syntactical and incorrect operation errors; and providing guidance when something unexpected occurs. These messages become an important validation tool for the users to identify system bottlenecks.
Software Verification and Validation
Software testing is used in association with verification and validation:
Verification: Have we built the software right (i.e., does it match the specification?)? It is process based.
Validation: Have we built the right software (i.e., is this what the customer wants?)? It is product based.
The terms verification and validation are commonly used interchangeably in the industry; it is also common to see these two terms incorrectly defined.
According to the IEEE Standard Glossary of Software Engineering Terminology: Verification is the process of evaluating a system or component to determine whether the products of a given development phase satisfy the conditions imposed at the start of that phase.
Validation is the process of evaluating a system or component during or at the end of the development process to determine whether it satisfies specified requirements.
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| Figure 3 Functional Testing (Source: Adventnet.com) |
Software Testing Team
Software testing (Figure 3, above can be done by software testers. Until the 1980s the term "software tester" was used generally, but later it was also seen as a separate profession.
Regarding the periods and the different goals in software testing, different roles have been established: manager, test lead, test designer, tester, automation developer, and test administrator.
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| Figure 4 Risk Assessment (Source: Rice Consulting) |
Though controversial, software testing may be viewed as an important part of the software quality assurance (SQA) process. In SQA, software process specialists and auditors take a broader view on software and its development. They examine and change the software engineering process itself to reduce the amount of faults that end up in the delivered software: the so-called defect rate.
What constitutes an "acceptable defect rate" depends on the nature of the software. For example, an arcade video game designed to simulate flying an airplane would presumably have a much higher tolerance for defects than mission critical software used to control the functions of an airliner that really is flying!
Although there are close links with SQA, testing departments often exist independently, and there may be no SQA function in some companies. Software
Testing is a task intended to detect defects in software by contrasting a computer program's expected results with its actual results for a given set of inputs. By contrast, QA (Quality Assurance) is the implementation of policies and procedures intended to prevent defects from occurring in the first place.
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