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There is considerable variety among
software testing Software testing is the act of checking whether software satisfies expectations. Software testing can provide objective, independent information about the Quality (business), quality of software and the risk of its failure to a User (computin ...
writers and consultants about what constitutes responsible software testing. Proponents of a context-driven approach consider much of the writing about software testing to be doctrine, while others believe this contradicts the
IEEE 829 Status of IEEE 829 Note: IEEE 829-2008 has been superseded by ISO/IEC/IEEE 29119-3:2013. Background to IEEE 829 IEEE 829-2008, also known as the 829 Standard for Software and System Test Documentation, was an IEEE standard that specified the f ...
documentation standard.


Best practices

Proponents of the context-driven approach believe that there are no best practices of testing, but rather that testing is a set of skills that allow the tester to select or invent testing practices to suit each unique situation.
James Marcus Bach James Marcus Bach (born ) is an American software tester, author, trainer, and consultant. Career In his autobiography, Bach wrote that he worked as a software testing manager for Apple and Borland after dropping out of high school. He also progr ...
wrote "...there is no practice that is better than all other possible practices, regardless of the context." However, some testing practitioners do not see an issue with the concept of "best practices" and do not believe that term implies that a practice is universally applicable.


Types of software testing


Agile vs. traditional

Around 1990, a new style of writing about testing began to challenge previous approaches. The seminal work in this area is often regarded as Testing Computer Software by Cem Kaner. Instead of the assumption that testers have full access to source code and complete specifications, these writers, including Kaner and
James Bach James Marcus Bach (born ) is an American software tester, author, trainer, and consultant. Career In his autobiography, Bach wrote that he worked as a software testing manager for Apple and Borland after dropping out of high school. He also progr ...
, argued that testers must learn to work under conditions of uncertainty and constant change. Meanwhile, an opposing trend toward process "maturity" also gained ground, in the form of the
Capability Maturity Model The Capability Maturity Model (CMM) is a development model created in 1986 after a study of data collected from organizations that contracted with the U.S. Department of Defense, who funded the research. The term "maturity" relates to the degree ...
. The agile testing movement, which includes but is not limited to testing methods practiced on agile development projects, is popular mainly in commercial circles, whereas CMM was embraced by government and military software providers. However, saying that "maturity models" like CMM gained ground against or opposing Agile testing may not be right. Agile movement is a 'way of working', while CMM is a process improvement idea. But another point of view must be considered: the operational culture of an organization. While it may be true that testers must have an ability to work in a world of uncertainty, it is also true that their flexibility must have direction. In many cases test cultures are self-directed and as a result fruitless, unproductive results can ensue. Furthermore, providing positive evidence of defects may either indicate that you have found the tip of a much larger problem, or that you have exhausted all possibilities. A framework is a test of Testing. It provides a boundary that can measure (validate) the capacity of our work. Both sides have continued to debate the merits of their approaches, but the true measure lies in assessing delivery quality. Testing systematically without broader focus can be ineffective, while finding numerous errors does not necessarily mean Agile methods were the cause; it may simply indicate poor initial work.


Exploratory vs. scripted

Exploratory test Exploratory testing is an approach to software testing that is concisely described as simultaneous learning, test design and test execution. Cem Kaner, who coined the term in 1984, defines exploratory testing as "a style of software testing that em ...
ing means simultaneous test design and test execution with an emphasis on learning. Scripted testing means that learning and test design happen prior to test execution, and quite often the learning has to be done again during test execution. Exploratory testing is very common, but in most writing and training about testing it is barely mentioned and generally misunderstood. Some writers consider it a primary and essential practice. Structured exploratory testing is a compromise when the testers are familiar with the software. A vague test plan, known as a test charter, is written up, describing what functionalities need to be tested but not how, allowing the individual testers to choose the method and steps of testing. There are two main disadvantages associated with a primarily exploratory testing approach. The first is that there is no opportunity to prevent defects, which can happen when the designing of tests in advance serves as a form of structured static testing that often reveals problems in system requirements and design. The second is that, even with test charters, demonstrating test coverage and achieving repeatability of tests using a purely exploratory testing approach is difficult. For this reason, a blended approach of scripted and exploratory testing is often used to reap the benefits while mitigating each approach's disadvantages.


Manual vs. automated

Some writers believe that
test automation In software testing, test automation is the use of software separate from the software being tested to control the execution of tests and the comparison of actual outcomes with predicted outcomes. Test automation can automate some repetitive bu ...
is so expensive relative to its value that it should be used sparingly. Others, such as advocates of
agile development Agile software development is an umbrella term for approaches to developing software that reflect the values and principles agreed upon by ''The Agile Alliance'', a group of 17 software practitioners, in 2001. As documented in their ''Manifesto ...
, recommend automating 100% of all tests. A challenge with automation is that automated testing requires automated test oracles (an oracle is a mechanism or principle by which a problem in the software can be recognized). Such tools have value in load testing software (by signing on to an application with hundreds or thousands of instances simultaneously), or in checking for intermittent errors in software. The success of automated software testing depends on complete and comprehensive test planning. Software development strategies such as
test-driven development Test-driven development (TDD) is a way of writing source code, code that involves writing an test automation, automated unit testing, unit-level test case that fails, then writing just enough code to make the test pass, then refactoring both the ...
are highly compatible with the idea of devoting a large part of an organization's testing resources to automated testing. Many large software organizations perform automated testing. Some have developed their own automated testing environments specifically for internal development, and not for resale.


Software design vs. software implementation

Ideally, software testers should not be limited only to testing software implementation, but also to testing software design. With this assumption, the role and involvement of testers will change dramatically. In such an environment, the test cycle will change too. To test software design, testers would review requirement and design specifications together with designer and programmer, potentially helping to identify bugs earlier in software development.


Oversight

One principle in software testing is summed up by the classical Latin question posed by Juvenal: '' Quis Custodiet Ipsos Custodes'' (Who watches the watchmen?), or is alternatively referred informally, as the "
Heisenbug In computer programming jargon, a heisenbug is a software bug that seems to disappear or alter its behavior when one attempts to study it. The term is a pun on the name of Werner Heisenberg, the physicist who first asserted the observer effect ...
" concept (a common misconception that confuses
Heisenberg Werner Karl Heisenberg (; ; 5 December 1901 – 1 February 1976) was a German theoretical physicist, one of the main pioneers of the theory of quantum mechanics and a principal scientist in the German nuclear program during World War II. He pub ...
's
uncertainty principle The uncertainty principle, also known as Heisenberg's indeterminacy principle, is a fundamental concept in quantum mechanics. It states that there is a limit to the precision with which certain pairs of physical properties, such as position a ...
with
observer effect Observer effect, observer bias, observation effect, or observation bias may refer to a number of concepts, some of them closely related: General experimental biases * Hawthorne effect, a form of reactivity in which subjects modify an aspect of th ...
). The idea is that any form of observation is also an interaction, that the act of testing can also affect that which is being tested. In practical terms, the test engineer is testing software (and sometimes hardware or
firmware In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, h ...
) with other software (and hardware and firmware). The process can fail in ways that are not the result of defects in the target but rather result from defects in (or indeed intended features of) the testing tool. There are metrics being developed to measure the effectiveness of testing. One method is by analyzing
code coverage In software engineering, code coverage, also called test coverage, is a percentage measure of the degree to which the source code of a program is executed when a particular test suite is run. A program with high code coverage has more of its ...
(this is highly controversial) - where everyone can agree what areas are not being covered at all and try to improve coverage in these areas. Bugs can also be placed into code on purpose, and the number of bugs that have not been found can be predicted based on the percentage of intentionally placed bugs that were found. The problem is that it assumes that the intentional bugs are the same type of bug as the unintentional ones. Finally, there is the analysis of historical find-rates. By measuring how many bugs are found and comparing them to predicted numbers (based on past experience with similar projects), certain assumptions regarding the effectiveness of testing can be made. While not an absolute measurement of quality, if a project is halfway complete and there have been no defects found, then changes may be needed to the procedures being employed by QA.


References

{{reflist Software testing