Software QA and Testing Frequently-Asked-Questions, Part 1
- What is 'Software Quality Assurance'?
- What is 'Software Testing'?
- What are some recent major computer system failures caused by software bugs?
- Does every software project need testers?
- Why does software have bugs?
- How can new Software QA processes be introduced in an existing organization?
- What is verification? validation?
- What is a 'walkthrough'?
- What's an 'inspection'?
- What kinds of testing should be considered?
- What are 5 common problems in the software development process?
- What are 5 common solutions to software development problems?
- What is software 'quality'?
- What is 'good code'?
- What is 'good design'?
- What is SEI? CMM? CMMI? ISO? Will it help?
- What is the 'software life cycle'?
What is 'Software Quality Assurance'?
Software QA involves the entire software development PROCESS - monitoring
and improving the process, making sure that any agreed-upon processes, standards and
procedures are followed, and ensuring that problems are found and
dealt with. It is oriented to 'prevention'.
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What is 'Software Testing'?
Testing involves operation of a system or application under controlled
conditions and evaluating the results (e.g., 'if the user
is in interface A of the application while using hardware B,
and does C, then D should happen'). The controlled conditions
should include both normal and abnormal conditions. Testing should
intentionally attempt to make things go wrong to determine if things
happen when they shouldn't or things don't happen when they should.
It is oriented to 'detection'.
- Organizations vary considerably in how they assign responsibility for QA and testing. Sometimes they're the combined responsibility of one group or individual. Also common are project teams and agile teams that include a mix of testers and developers who work closely together, with overall testing and QA processes monitored by a project manager, a scrum master, or other appropriate person. It will depend on what best fits an organization's size, development approach, and business structure.
- Note that testing can be done by machines or people. When done by machines (computers usually) it's often called 'automated testing' - see the SoftwareQATest.com LFAQ page for more information about automated testing. Of course a human still has to develop the automation strategy and test cases and write test automation code.
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What are some recent major computer system failures caused by software bugs?
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Does every software project need testers?
While all projects will benefit from testing, some projects may
not require independent test staff to succeed.
Which projects may not need independent test staff? The answer depends on the size and context of the project, the risks, the development methodology, the skill and experience of the developers, and other factors. For instance, if the project is a short-term, small, low risk project, with highly experienced programmers utilizing thorough unit testing or test-first development, then test engineers may not be required for the project to succeed.
In some cases an IT organization may be too small or new to have a testing staff even if the situation calls for it. In these circumstances it may be appropriate to instead use contractors or outsourcing, or adjust the project management and development approach (by switching to more senior developers and test-first development, for example). Inexperienced managers sometimes gamble on the success of a project by skipping thorough testing or having programmers do post-development functional testing of their own work, a decidedly high risk gamble.
For non-trivial-size projects or projects with non-trivial risks, a testing staff is usually necessary. As in any business, the use of personnel with specialized skills enhances an organization's ability to be successful in large, complex, or difficult tasks. It allows for both a) deeper and stronger skills and b) the contribution of differing perspectives. For example, programmers typically have the perspective of 'what are the technical issues in making this functionality work?'. A test engineer typically has the perspective of 'what might go wrong with this functionality, and how can we ensure it meets expectations?'. A technical person who can be highly effective in approaching tasks from both of those perspectives is rare, which is why, sooner or later, organizations bring in test specialists.
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- miscommunication or no communication - as to specifics of what an application should or shouldn't do (the application's requirements).
- software complexity - the complexity of current software applications can be difficult to comprehend for anyone without experience in modern-day software development. Multi-tier distributed systems, applications utilizing multiple local and remote web services, use of cloud infrastructure, data communications, enormous/distributed datastores, security complexities, and sheer size of applications have all contributed to the exponential growth in software/system complexity.
- programming errors - programmers, like anyone else, can make mistakes.
- dependencies among code modules, services, systems, other projects, etc may not be well understood, and may cause unexpected problems.
- in some fast-changing business environments, continuously changing specifications may be a fact of life, thus introducing significant added risk. Agile software development approaches - if effectively implemented - can help mitigate this. See more about 'agile' approaches in Part 2 of the FAQ.
- time pressures - scheduling of software projects is difficult at best, often requiring a lot of guesswork. When deadlines loom and the crunch comes, mistakes will be made.
- egos - people prefer to say things like:
'no problem' 'piece of cake' 'I can whip that out in a few hours' 'it should be easy to update that old code' instead of: 'that adds a lot of complexity and we could end up making a lot of mistakes' 'we have no idea if we can do that; we'll wing it' 'I can't estimate how long it will take, until I take a close look at it' 'we can't figure out what that old spaghetti code did in the first place' If there are too many unrealistic 'no problem's', the result may be bugs. - poorly designed/documented code - it's tough to maintain and modify code that is badly written or poorly commented/documented; the result is bugs. In many organizations management provides no incentive for programmers to write clear, understandable, maintainable code. In fact, it's usually the opposite: they get points mostly for quickly turning out code, and there's job security if nobody else can understand it ('if it was hard to write, it should be hard to read').
- software development tools - IDE's, libraries, external apps/services, compilers, scripting tools, etc. often introduce their own bugs or are poorly documented, or have usability issues, resulting in added bugs.
- services or microservices on which the software depends also often introduce their own bugs or performance problems, are not well understood, or may be unreliable, resulting in added bugs.
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How can new Software QA processes be introduced in an existing organization?
- A lot depends on the size of the organization and the risks involved. For large organizations with high-risk (in terms of lives or property) projects, serious management buy-in is required and a more formalized QA process may be necessary.
- Where the risk is lower, management and organizational buy-in and QA implementation may be a slower, step-at-a-time process. QA processes should be balanced with productivity so as to keep bureaucracy from getting out of hand.
- For small groups or projects, a more ad-hoc process may be appropriate, depending on the type of customers and projects. A lot will depend on team leads or managers, feedback to/from developers, and ensuring adequate communications among customers, managers, developers, testers, and other stakeholders.
- The most value for effort will often be in (a) requirement/user story management processes, with a goal of clear, complete, testable specifications embodied in requirements, appropriately-sized user stories, or design documentation, (b) design reviews and code reviews, and (c) post-mortems/retrospectives. Agile approaches utilizing extensive regular communication among the development team and product owner and other stakeholders can coordinate well with improved QA processes.
- Other possibilities include incremental approaches such as Lean/Kaizen methods of continuous process improvement, the Deming-Shewhart Plan-Do-Check-Act cycle, and others.
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What is verification? validation?
Verification typically involves reviews and meetings to evaluate
documents, plans, code, requirements, and specifications. This
can be done with checklists, issues lists, walkthroughs, and
inspection meetings. Validation typically involves actual
testing and takes place after verifications are completed.
The term 'IV & V' refers to Independent Verification and
Validation.
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What is a 'walkthrough'?
A 'walkthrough' is an informal meeting for evaluation or
informational purposes. Little or no preparation is usually
required.
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What's an 'inspection'?
An inspection is more formalized than a 'walkthrough', typically
with 3-8 people including a moderator, reader, and a recorder to
take notes. The subject of the inspection is typically a document
such as a requirements spec or a test plan, and the purpose is to
find problems and see what's missing, not to fix anything. Attendees
should prepare for this type of meeting by reading thru the document;
most problems will be found during this preparation. The result of the
inspection meeting should be a written report. Thorough preparation for
inspections is difficult, painstaking work, but is one of the most cost
effective methods of ensuring quality. Employees who are most skilled
at inspections are like the 'eldest brother' in the parable in
'Why is it often hard for organizations
to get serious about quality assurance?'.
Their skill may have low visibility but they are extremely valuable
to any software development organization, since bug prevention is
far more cost-effective than bug detection.
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What kinds of testing should be considered?
- black box testing - not based on any knowledge of internal design or code. Tests are based on requirements and functionality.
- white box testing - based on knowledge of the internal logic of an application's code. Tests are based on coverage of code statements, branches, paths, conditions.
- unit testing - the most 'micro' scale of testing; to test particular functions or code modules. Typically done by the programmer and not by testers, as it requires detailed knowledge of the internal program design and code. Not always easily done unless the application has a well-designed architecture with tight code; may require developing test driver modules or test harnesses.
- API testing - testing of messaging/data exchange among systems or components of systems. Such testing usually does not involve GUI's (graphical user interfaces). It is often considered a type of 'mid-level' testing.
- incremental integration testing - continuous testing of an application as new functionality is added; requires that various aspects of an application's functionality be independent enough to work separately before all parts of the program are completed, or that test drivers be developed as needed; done by programmers or by testers.
- integration testing - testing of combined parts of an application to determine if they function together correctly. The 'parts' can be code modules, services, individual applications, client and server applications on a network, etc. This type of testing is especially relevant to multi-tier and distributed systems.
- functional testing - black-box type testing geared to functional requirements of an application; this type of testing should be done by testers. This doesn't mean that the programmers shouldn't check that their code works before releasing it (which of course applies to any stage of testing.)
- system testing - black-box type testing that is based on overall requirements specifications; covers all combined parts of a system.
- end-to-end testing - similar to system testing; the 'macro' end of the test scale; involves testing of a complete application environment in a situation that mimics real-world use, such as interacting with a database, using network communications, or interacting with other hardware, applications, or systems if appropriate.
- sanity testing or smoke testing - typically an initial testing effort to determine if a new software version is performing well enough to accept it for a major testing effort. For example, if the new software is crashing systems every 5 minutes, bogging down systems to a crawl, or corrupting databases, the software may not be in a 'sane' enough condition to warrant further testing in its current state.
- regression testing - re-testing after fixes or modifications of the software or its environment. It can be difficult to determine how much re-testing is needed, especially near the end of the development cycle. Automated testing approaches can be especially useful for this type of testing.
- acceptance testing - final testing based on specifications of the end-user or customer, or based on use by end-users/customers over some limited period of time.
- load testing - testing an application under heavy loads, such as testing of a web site under a range of loads to determine at what point the system's response time degrades or fails.
- stress testing - term often used interchangeably with 'load' and 'performance' testing. Also used to describe such tests as system functional testing while under unusually heavy loads, heavy repetition of certain actions or inputs, input of large numerical values, large complex queries to a database system, etc.
- performance testing - term often used interchangeably with 'stress' and 'load' testing. Ideally 'performance' testing (and any other 'type' of testing) is defined in requirements documentation or QA or Test Plans.
- usability testing - testing for 'user-friendliness'. Clearly this is subjective, and will depend on the targeted end-user or customer. User interviews, surveys, video recording of user sessions, and other techniques can be used. Programmers and testers are usually not appropriate as usability testers.
- accessibility testing (sometimes called '508 testing', in reference to Section 508 of a U.S. federal law, covering government-related software systems), is a type of usability testing oriented toward users with disabilites.
- install/uninstall testing - testing of full, partial, or upgrade install/uninstall processes.
- recovery testing - testing how well a system recovers from crashes, hardware failures, or other catastrophic problems.
- failover testing - typically used interchangeably with 'recovery testing'
- security testing - testing how well the system protects against unauthorized internal or external access, willful damage, etc; may require sophisticated testing techniques.
- compatibility testing - testing how well software performs in a particular hardware/software/operating system/network/etc. environment.
- exploratory testing - often taken to mean a creative, informal software test that is not based on formal test plans or test cases; testers may be learning the software as they test it.
- ad-hoc testing - similar to exploratory testing, but often taken to mean that the testers have significant understanding of the software before testing it.
- context-driven testing - testing driven by an understanding of the environment, culture, and intended use of software. For example, the testing approach for life-critical medical equipment software would be completely different than that for a low-cost computer game.
- user acceptance testing - determining if software is satisfactory to an end-user or customer.
- comparison testing - comparing software weaknesses and strengths to competing products.
- alpha testing - testing of an application when development is nearing completion; minor design changes may still be made as a result of such testing. Typically done by end-users or others, not by programmers or testers.
- beta testing - testing when development and testing are essentially completed and final bugs and problems need to be found before final release. Typically done by end-users or others, not by programmers or testers.
- mutation testing - a method for determining if a set of test data or test cases is useful, by deliberately introducing various code changes ('bugs') and retesting with the original test data/cases to determine if the 'bugs' are detected. Proper implementation requires large computational resources.
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What are 5 common problems in the software development process?
- poor requirements, user stories, or acceptance criteria - if these are unclear, incomplete, too general, or not testable, there may be problems.
- unrealistic schedule or story points - if too much work is crammed in too little time, problems are inevitable.
- inadequate testing - no one may know whether or not the software is any good until customers complain or systems crash.
- misunderstandings about dependencies.
- miscommunication - if developers don't know what's needed or stakeholders have erroneous expectations, problems can be expected.
In agile projects, problems often occur when the project diverges from agile principles (such as forgetting that 'Business people and developers must work together daily throughout the project.' or 'The most efficient and effective method of conveying information to and within a development team is face-to-face conversation.' - see the Manifesto for Agile Software Development.)
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What are 5 common solutions to software development problems?
- solid requirements/user stories/acceptance criteria - clear, complete, appropriately detailed, cohesive, attainable, testable specifications or acceptance criteria that are agreed to by all players. In 'agile'-type environments, continuous close coordination with product owners or their representatives is necessary to ensure that changing/emerging requirements are understood.
- realistic schedules - allow adequate time for planning, design, testing, bug fixing, re-testing, changes, and documentation; personnel should be able to complete the project without burning out, and be able to work at a sustainable pace.
- adequate testing - start testing early on, re-test after fixes or changes, plan for adequate time for testing and bug-fixing. 'Early' testing could include static code analysis/testing, test-first development, unit testing by developers, built-in testing and diagnostic capabilities, etc. Automated testing can contribute significantly if effectively designed and implemented as part of an overall testing strategy.
- stick to initial requirements/criteria where feasible - be prepared to defend against excessive changes and additions once development has begun or after a sprint has begun, and be prepared to explain consequences. If changes are necessary, they should be adequately reflected in related schedule changes or story/point changes. If possible, work closely with customers/end-users to manage expectations. In agile environments, it is acceptable that requirements may change often, requiring that true agile processes be in place and followed. Note that in true agile practices stories should not change during a sprint.
- communication - require walkthroughs/inspections/reviews when appropriate; make extensive use of group communication tools - groupware, wiki's, bug-tracking tools, change management tools, audio/video conferencing, etc.; ensure that information/documentation/user stories are available, up-to-date, and appopriately detailed; promote teamwork and cooperation; use prototypes, frequent deliveries, and/or continuous communication with end-users if possible to clarify expectations. In effective agile environments most of these should be taking place.
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What is software 'quality'?
Quality software is reasonably bug-free, delivered on time
and within budget, meets requirements, acceptance criteria,
and/or expectations, and is maintainable.
However, quality is obviously a subjective term. It
will depend on who the 'customer' is and their overall
influence in the scheme of things. A wide-angle view of
the 'customers' of a software development project might include
end-users, product owners, customer acceptance testers, customer contract
officers, customer management, the development organization's
management/accountants/testers/salespeople, future software
maintenance engineers, stockholders, magazine columnists, etc.
Each type of 'customer' will have their own slant on 'quality' -
the accounting department might define quality in terms of profits
while an end-user might define quality as user-friendly and
bug-free.
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What is 'good code'?
'Good code' is code that works, is reasonably bug free, secure, and is readable
and maintainable. Some organizations have coding 'standards' that
all developers are supposed to adhere to, but everyone has different ideas
about what's best, or what is too many or too few rules. There are
also various theories and metrics, such as McCabe Complexity metrics.
It should be kept in mind that excessive use of standards and rules
can stifle productivity and creativity. 'Peer reviews', 'buddy checks'
pair programming, code analysis tools, etc. can be used to check for
problems and enforce standards.
For example, in C/C++ coding, here are some typical ideas to consider
in setting rules/standards; these may or may not apply to
a particular situation:
- minimize or eliminate use of global variables.
- use descriptive function and method names - use both upper and lower case, avoid abbreviations, use as many characters as necessary to be adequately descriptive (use of more than 20 characters is not out of line); be consistent in naming conventions.
- use descriptive variable names - use both upper and lower case, avoid abbreviations, use as many characters as necessary to be adequately descriptive (use of more than 20 characters is not out of line); be consistent in naming conventions.
- function and method sizes should be minimized; less than 100 lines of code is good, less than 50 lines is preferable.
- function/method descriptions should be clearly spelled out in comments preceding a function's/method's code.
- organize code for readability.
- use whitespace generously - vertically and horizontally
- each line of code should contain 70 characters max.
- one code statement per line.
- coding style should be consistent throughout a program (e.g., use of brackets, indentations, naming conventions, etc.)
- in adding comments, err on the side of too many rather than too few comments; a common rule of thumb is that there should be at least as many lines of comments (including header blocks) as lines of code.
- no matter how small, an application should include documentation of the overall program function and flow (even a few paragraphs is better than nothing); or if possible a separate flow chart and detailed program documentation.
- make extensive use of error handling procedures and status and error logging.
- for C++, to minimize complexity and increase maintainability, avoid too many levels of inheritance in class hierarchies (relative to the size and complexity of the application). Minimize use of multiple inheritance, and minimize use of operator overloading (note that the Java programming language eliminates multiple inheritance and operator overloading.)
- for C++, keep class methods small, less than 50 lines of code per method is preferable.
- for C++, make liberal use of exception handlers
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What is 'good design'?
'Design' could refer to many things, but often refers to
'functional design' or 'internal design'. Good internal
design is indicated by software code whose overall
structure is clear, understandable, easily modifiable, and
maintainable; is robust with sufficient error-handling and
status logging capability; and works as expected when implemented.
Good functional design is indicated by an application whose
functionality can be traced back to customer and end-user
requirements or user stories. (See further discussion of functional
and internal design in FAQ
'What's the big deal about requirements?').
For programs that have a user interface, it's often a
good idea to assume that the end user will have little computer
knowledge and may not read a user manual or even the on-line
help; some common rules-of-thumb include:
- the program should act in a way that least surprises the user
- it should always be evident to the user what can be done next and how to exit
- the program shouldn't let the users do something stupid without warning them.
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What is SEI? CMM? CMMI? ISO? IEEE? ANSI? Will it help?
- SEI = 'Software Engineering Institute' at Carnegie-Mellon University; initiated by the U.S. Defense Department to help improve software development processes.
- CMM = 'Capability Maturity Model', now called the CMMI ('Capability Maturity Model Integration'), developed by the SEI and as of January 2013 overseen by the CMMI Institute at Carnegie Mellon University. In the 'staged' version, it's a model of 5 levels of process 'maturity' that help determine effectiveness in delivering quality software. CMMI models are "collections of best practices that help organizations to improve their processes." It is geared to larger organizations such as large U.S. Defense Department contractors. However, many of the QA processes involved are appropriate to any organization, and if reasonably applied can be helpful. Organizations can receive CMMI ratings by undergoing assessments by qualified auditors. CMMI V1.3 (2010) also supports Agile development processes. See the searchable CMMI assessment results database.
Level 1 - 'Initial': characterized by chaos, periodic panics, and heroic efforts
required by individuals to successfully complete projects. Few if any
processes in place; successes may not be repeatable.
Level 2 - 'Managed': projects carried out in accordance with policies and employ
skilled personnel with sufficient resources. Project tracking and reporting
is in place. Schedules and budgets are set and revised as needed. Work
products are appropriately controlled.
Level 3 - 'Defined': standard development and maintenance processes are established,
integrated consistently throughout an organization,
Level 4 - 'Quantitatively Managed': metrics are used to track process performance.
Project performance is controlled and predictable.
Level 5 - 'Optimizing': the focus is on continuous process improvement. The impact of
new processes and technologies can be predicted and effectively implemented
when required. Quality and process objectives are established and regularly
revised to reflect changing objectives and organizational performance, and
used as criteria in managing process improvement.
Perspective on CMMI ratings: During 2017, of 2800 organizations appraised,
it was reported that 10% of appraisals were at Level 4 or 5; 70% of appraised
organizations had less than 100 employees; 50% of appraisals were in China,
other Asia 20%, and 20% in N. America; and 80% were using agile methodologies.
During 2002-2005, of 782 organizations assessed, 4% were rated at Level 1,
34% at 2, 30% at 3, 4% at 4, and 19% at Level 5. 37% were government
contractors or agencies, and 68% had more than 100 employees; 88% were software-related
organizations. (The CMMI applies to a wide variety of organizations, not just software
organizations.) The majority of organizations were NOT U.S.-based.
- ISO = 'International Organisation for Standardization' -
The ISO 9001:2015 standard (the ISO standard is updated periodically,
indicated by the year designation ) concerns quality systems that are assessed
by outside auditors, and it applies to many kinds of production
and manufacturing organizations, not just software. It covers
documentation, design, development, production, testing, installation,
servicing, and other processes. The full set of standards consists of:
(a)ISO 9001:2015 - Quality Management Systems: Requirements;
(b)ISO 9000:2015 - Quality Management Systems: Fundamentals and
Vocabulary;
(c)ISO 9004:2009 - Quality Management Systems: Guidelines for
Performance Improvements.
(d)ISO 19011:2011 - Guidelines for auditing management systems.
To be ISO 9001 certified, a third-party auditor assesses an organization,
and certification is typically good for about 3 years, after which a
complete reassessment is required. Note that ISO certification does not
necessarily indicate quality products - it indicates only that documented
processes are followed. There are also other software-related ISO standards
such as ISO/IEC 25010 which includes a 'quality in use model' composed of five
characteristics and a 'product quality model' that covers eight main characteristics
of software. Also see
https://www.iso.org/ for the
latest information. In the U.S. the standards can also be purchased
via the ASQ web site at
http://asq.org/quality-press/
ISO/IEC 25002 is a software quality evaluation standard that defines (a) a 'quality in use model' of five characteristics that relate to the outcome of interaction when a product is used in a particular context of use, and (b) a 'product quality model' composed of eight characteristics that relate to static properties of software and dynamic properties of the computer system.
ISO/IEC/IEEE 29119 series of standards for software testing.
ISO/IEC/IEEE 29119-1: Concepts & Definitions
ISO/IEC/IEEE 29119-2: Test Processes
ISO/IEC/IEEE 29119-3: Test Documentation
ISO/IEC/IEEE 29119-4: Test Techniques
ISO/IEC/IEEE 29119-5: Keyword Driven Testing
- IEEE = 'Institute of Electrical and Electronics Engineers' - among other things, creates standards such as 'IEEE Standard for Software Test Documentation' (IEEE/ANSI Standard 829), 'IEEE Standard of Software Unit Testing (IEEE/ANSI Standard 1008), 'IEEE Standard for Software Quality Assurance Plans' (IEEE/ANSI Standard 730), and others.
- ANSI = 'American National Standards Institute', the primary industrial standards body in the U.S.; publishes some software-related standards in conjunction with the IEEE and ASQ (American Society for Quality).
- Other software development/IT management process assessment methods besides CMMI and ISO 9000 include SPICE, Trillium, TickIT, Bootstrap, ITIL, MOF, and CobiT.
- See the Softwareqatest.com 'Other Resources' section for further information available on the web.
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What is the 'software life cycle'?
The life cycle begins when an application is first conceived
and ends when it is no longer in use. It includes aspects such as
initial concept, requirements analysis, functional design,
internal design, documentation planning, test planning, coding,
document preparation, integration, testing, maintenance,
updates, retesting, phase-out, agile sprints, and other aspects.