Introduction to Test
In Module 0 read Intorduction to Testing: Purpose and Relation
to Other Disciplines to begin the course. The Concepts will be
analyzed in the other Modules.
Concepts
The Test discipline acts in many respects as a service provider to the other
disciplines. Testing focuses primarily on the evaluation or assessment of quality
realized through a number of core practices:
- Finding and documenting defects in software quality.
- Generally advising about perceived software quality.
- Proving the validity of the assumptions made in design and requirement specifications
through concrete demonstration.
- Validating the software product functions as designed.
- Validating that the requirements have been implemented appropriately.
An interesting but somewhat subtle difference between Test and the other disciplines
in RUP is that testing is essentially tasked with finding and exposing weaknesses
in the software product. For this effort to be successful, this necessitates
a somewhat negative and destructive rather than constructive approach. The challenge
is to avoid both an approach that does not suitably and effectively challenge
the software and expose it's inherent problems and weaknesses, and an approach
that is so destructive that it will likely never find it possible to consider
the quality of the software product acceptable.
Based on information presented in various surveys and essays, software testing
is said to account for 30 to 50 percent of total software development costs.
It is therefore perhaps surprising to note that most people believe computer
software is not well tested before it is delivered. This contradiction is rooted
in a few key issues.
First, testing software is enormously difficult. The different ways a given
program can behave are unquantifiable. Second, testing is typically done without
a clear methodology so results vary from project to project, organization to
organization: success is primarily a factor of the quality and skills of the
individuals. Third, insufficient use is made of productivity tools, making the
laborious aspects of testing manageable: in addition to the lack of automated
test execution, many test efforts are conducted without tools that allow the
effect management of extensive Test Data and Test Results. While the flexibility
of use and complexity of software makes complete testing an impossible goal,
a well-conceived methodology and use of state-of-the-art tools, can help to
improve the productivity and effectiveness of the software testing.
For "safety-critical" systems where a failure can harm people (such
as air-traffic control, missile guidance, or medical delivery systems), high-quality
software is essential for the success of the system. For a typical MIS system,
the criticality of the system may not be as immediately obvious, but it's likely
that the impact of a defect could cause the business using the software considerable
expense in lost revenue or possibly legal costs. In this "information age",
with increasing demand on provision of electronically delivered services over
the Internet, many MIS systems are now considered "mission-critical";
that is, companies cannot fulfill their functions and experience massive losses
when failures occur.
A continuous approach to quality, initiated early in the software lifecycle,
can significantly lower the cost of completing and maintaining the software.
This greatly reduces the risk associated with deploying poor quality software.
The Test discipline is related to other disciplines.
- The Requirements discipline captures requirements for the
software product, and those requirements are one of the primary inputs for
identifying what tests to perform.
- The Analysis & Design discipline determines the appropriate
design for the software product; this is the another important input for identifying
what tests to perform.
- The Implementation discipline produces builds of the software
product that are validated by the Test discipline. Within an iteration multiple
builds will be tested, typically one per test cycle.
- The Environment discipline develops and maintains supporting
artifacts that are used during test, such as the Test Guidelines and Test
Environment.
- The Management discipline plans the project, and the necessary
work in each iteration. Described in an Iteration Plan, this artifact is an
important input to defining the correct evaluation mission for the test effort.
- The Configuration & Change Management discipline controls
change within the project team. The test effort verifies that each change
has been completed appropriately.
Copyright
© 1987 - 2001 Rational Software Corporation
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