Software QA and Testing Frequently-Asked-Questions, Part 1

What is 'Software Quality Assurance'?
What is 'Software Testing'?
Are there still major computer system failures caused by software bugs?
Why is it often hard for management to get serious about quality assurance?
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? ISO? Will it help?
What is the 'software life cycle'?
Will automated testing tools make testing easier?

What is 'Software Quality Assurance'?
Software QA involves the entire software development PROCESS - monitoring and improving the process, making sure that any agreed-upon standards and procedures are followed, and ensuring that problems are found and dealt with. It is oriented to 'prevention'. (See the Bookstore section's 'Software QA' category for a list of useful books on Software Quality Assurance.)

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What is 'Software Testing'?
Testing involves operation of a system or application under controlled conditions and evaluating the results (eg, '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'. (See the Bookstore section's 'Software Testing' category for a list of useful books on Software Testing.)

• 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 that include a mix of testers and developers who work closely together, with overall QA processes monitored by project managers. It will depend on what best fits an organization's size and business structure.

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Are there still major computer system failures caused by software bugs?

• In October of 1999 the $125 million NASA Mars Climate Orbiter spacecraft was believed to be lost in space due to a simple data conversion error. It was determined that spacecraft software used certain data in English units that should have been in metric units. Among other tasks, the orbiter was to serve as a communications relay for the Mars Polar Lander mission, which failed for unknown reasons in December 1999. Several investigating panels were convened to determine the process failures that allowed the error to go undetected.
• Bugs in software supporting a large commercial high-speed data network affected 70,000 business customers over a period of 8 days in August of 1999. Among those affected was the electronic trading system of the largest U.S. futures exchange, which was shut down for most of a week as a result of the outages.
• In April of 1999 a software bug caused the failure of a $1.2 billion military satellite launch, the costliest unmanned accident in the history of Cape Canaveral launches. The failure was the latest in a string of launch failures, triggering a complete military and industry review of U.S. space launch programs, including software integration and testing processes. Congressional oversight hearings were requested.
• A small town in Illinois received an unusually large monthly electric bill of $7 million in March of 1999. This was about 700 times larger than it's normal bill. It turned out to be due to bugs in new software that had been purchased by the local power company to deal with Y2K software issues.
• In early 1999 a major computer game company recalled all copies of a popular new product due to software problems. The company made a public apology for releasing a product before it was ready.
• The computer system of a major online U.S. stock trading service failed during trading hours several times over a period of days in February of 1999 according to nationwide news reports. The problem was reportedly due to bugs in a software upgrade intended to speed online trade confirmations.
• In April of 1998 a major U.S. data communications network failed for 24 hours, crippling a large part of some U.S. credit card transaction authorization systems as well as other large U.S. bank, retail, and government data systems. The cause was eventually traced to a software bug.
• January 1998 news reports told of software problems at a major U.S. telecommunications company that resulted in no charges for long distance calls for a month for 400,000 customers. The problem went undetected until customers called up with questions about their bills.
• In November of 1997 the stock of a major health industry company dropped 60% due to reports of failures in computer billing systems, problems with a large database conversion, and inadequate software testing. It was reported that more than $100,000,000 in receivables had to be written off and that multi-million dollar fines were levied on the company by government agencies.
• A retail store chain filed suit in August of 1997 against a transaction processing system vendor (not a credit card company) due to the software's inability to handle credit cards with year 2000 expiration dates.
• In August of 1997 one of the leading consumer credit reporting companies reportedly shut down their new public web site after less than two days of operation due to software problems. The new site allowed web site visitors instant access, for a small fee, to their personal credit reports. However, a number of initial users ended up viewing each others' reports instead of their own, resulting in irate customers and nationwide publicity. The problem was attributed to "...unexpectedly high demand from consumers and faulty software that routed the files to the wrong computers."
• In November of 1996, newspapers reported that software bugs caused the 411 telephone information system of one of the U.S. RBOC's to fail for most of a day. Most of the 2000 operators had to search through phone books instead of using their 13,000,000-listing database. The bugs were introduced by new software modifications and the problem software had been installed on both the production and backup systems. A spokesman for the software vendor reportedly stated that 'It had nothing to do with the integrity of the software. It was human error.'
• Software bugs caused the bank accounts of 823 customers of a major U.S. bank to be credited with $924,844,208.32 each in May of 1996, according to newspaper reports. The American Bankers Association claimed it was the largest such error in banking history. A bank spokesman said the programming errors were corrected and all funds were recovered.
• Software bugs in a Soviet early-warning monitoring system nearly brought on nuclear war in 1983, according to news reports in early 1999. The software was supposed to filter out false missile detections caused by Soviet satellites picking up sunlight reflections off cloud-tops, but failed to do so. Disaster was averted when a Soviet commander, based on a what he said was a '...funny feeling in my gut', decided the apparent missile attack was a false alarm. The filtering software code was rewritten.

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Why is it often hard for management to get serious about quality assurance?
Solving problems is a high-visibility process; preventing problems is low-visibility. This is illustrated by an old parable:
In ancient China there was a family of healers, one of whom was known throughout the land and employed as a physician to a great lord. The physician was asked which of his family was the most skillful healer. He replied,
"I tend to the sick and dying with drastic and dramatic treatments, and on occasion someone is cured and my name gets out among the lords."
"My elder brother cures sickness when it just begins to take root, and his skills are known among the local peasants and neighbors."
"My eldest brother is able to sense the spirit of sickness and eradicate it before it takes form. His name is unknown outside our home."

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Why does software have bugs?

• 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. Windows-type interfaces, client-server and distributed applications, data communications, enormous relational databases, and sheer size of applications have all contributed to the exponential growth in software/system complexity. And the use of object-oriented techniques can complicate instead of simplify a project unless it is well-engineered.
• programming errors - programmers, like anyone else, can make mistakes.
• changing requirements - the customer may not understand the effects of changes, or may understand and request them anyway - redesign, rescheduling of engineers, effects on other projects, work already completed that may have to be redone or thrown out, hardware requirements that may be affected, etc. If there are many minor changes or any major changes, known and unknown dependencies among parts of the project are likely to interact and cause problems, and the complexity of keeping track of changes may result in errors. Enthusiasm of engineering staff may be affected. In some fast-changing business environments, continuously modified requirements may be a fact of life. In this case, management must understand the resulting risks, and QA and test engineers must adapt and plan for continuous extensive testing to keep the inevitable bugs from running out of control - see 'What can be done if requirements are changing continuously?' 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 is bugs.
   
  

• poorly documented code - it's tough to maintain and modify code that is badly written or poorly documented; the result is bugs. In many organizations management provides no incentive for programmers to document their code or write clear, understandable 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 - visual tools, class libraries, compilers, scripting tools, etc. often introduce their own bugs or are poorly documented, 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 money) projects, serious management buy-in is required and a formalized QA process is 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 developers, and ensuring adequate communications among customers, managers, developers, and testers.
• In all cases the most value for effort will be in requirements management processes, with a goal of clear, complete, testable requirement specifications.

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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 (the author of whatever is being reviewed), 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 management 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.
• 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, individual applications, client and server applications on a network, etc. This type of testing is especially relevant to client/server 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 - 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 destroying 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 tools 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 'performace' 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.
• 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.
• security testing - testing how well the system protects against unauthorized internal or external access, willful damage, etc; may require sophisticated testing techniques.
• compatability testing - testing how well software performs in a particular hardware/software/operating system/network/etc. environment.
• acceptance testing - determining if software is stisfactory to a 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.

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What are 5 common problems in the software development process?

• poor requirements - if requirements are unclear, incomplete, too general, or not testable, there will be problems.
• unrealistic schedule - if too much work is crammed in too little time, problems are inevitable.
• inadequate testing - no one will know whether or not the program is any good until the customer complains or systems crash.
• featuritis - requests to pile on new features after development is underway; extremely common.
• miscommunication - if developers don't know what's needed or customer's have erroneous expectations, problems are guaranteed.

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What are 5 common solutions to software development problems?

• solid requirements - clear, complete, detailed, cohesive, attainable, testable requirements that are agreed to by all players. Use prototypes to help nail down requirements.
• 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.
• adequate testing - start testing early on, re-test after fixes or changes, plan for adequate time for testing and bug-fixing.
• stick to initial requirements as much as possible - be prepared to defend against changes and additions once development has begun, and be prepared to explain consequences. If changes are necessary, they should be adequately reflected in related schedule changes. If possible, use rapid prototyping during the design phase so that customers can see what to expect. This will provide them a higher comfort level with their requirements decisions and minimize changes later on.
• communication - require walkthroughs and inspections when appropriate; make extensive use of group communication tools - e-mail, groupware, networked bug-tracking tools and change management tools, intranet capabilities, etc.; insure that documentation is available and up-to-date - preferably electronic, not paper; promote teamwork and cooperation; use protoypes early on so that customers' expectations are clarified.

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What is software 'quality'?
Quality software is reasonably bug-free, delivered on time and within budget, meets requirements 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, 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. (See the Bookstore section's 'Software QA' category for useful books with more information.)

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What is 'good code'?
'Good code' is code that works, is bug free, 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' code analysis tools, etc. can be used to check for problems and enforce standards.
For C and 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 descriptions should be clearly spelled out in comments preceding a function's code.
• organize code for readability.
• use whitespace generously - vertically and horizintally
• each line of code should contain 70 characters max.
• one code statement per line.
• coding style should be consistent throught a program (eg, 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 documentaion 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 heirarchies (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 correctly when implemented. Good functional design is indicated by an application whose functionality can be traced back to customer and end-user requirements. (See further discussion of functional and internal design in 'What's the big deal about requirements?' in FAQ #2.) 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? 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', developed by the SEI. It's a model of 5 levels of organizational 'maturity' that determine effectiveness in delivering quality software. It is geared to large 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 CMM ratings by undergoing assessments by qualified auditors.

       Level 1 - 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 - software project tracking, requirements management,
                 realistic planning, and configuration management
                 processes are in place; successful practices can
                 be repeated.

       Level 3 - standard software development and maintenance processes
                 are integrated throughout an organization; a Software
                 Engineering Process Group is is in place to oversee
                 software processes, and training programs are used to
                 ensure understanding and compliance.

       Level 4 - metrics are used to track productivity, processes,
                 and products.  Project performance is predictable,
                 and quality is consistently high.

       Level 5 - the focus is on continouous process improvement. The
                 impact of new processes and technologies can be
                 predicted and effectively implemented when required.


      (Perspective on CMM ratings:  During 1992-1996 533 organizations
      were assessed.  Of those, 62% were rated at Level 1, 23% at 2,
      13% at 3, 2% at 4, and  0.4% at 5.  The median size of
      organizations was 100 software engineering/maintenance personnel;
      31% of organizations were U.S. federal contractors.  For those
      rated at Level 1, the most problematical key process area was
      in Software Quality Assurance.)

• ISO = 'International Organisation for Standards' - The ISO 9001, 9002, and 9003 standards concern quality systems that are assessed by outside auditors, and they apply to many kinds of production and manufacturing organizations, not just software. The most comprehensive is 9001, and this is the one most often used by software development organizations. It covers documentation, design, development, production, testing, installation, servicing, and other processes. ISO 9000-3 (not the same as 9003) is a guideline for applying ISO 9001 to software development organizations. The U.S. version of the ISO 9000 series standards is exactly the same as the international version, and is called the ANSI/ASQ Q9000 series. The U.S. version can be purchased directly from the ASQ (American Society for Quality) or the ANSI organizations. 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 9000 certification does not necessarily indicate quality products - it indicates only that documented processes are followed.
• 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 process assessment methods besides CMM and ISO 9000 include SPICE, Trillium, TickIT. and Bootstrap.
• See the '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, and other aspects. (See the Bookstore section's 'Software QA', 'Software Engineering', and 'Project Management' categories for useful books with more information.)

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Will automated testing tools make testing easier?

• Possibly. For small projects, the time needed to learn and implement them may not be worth it. For larger projects, or on-going long-term projects they can be valuable.
• A common type of automated tool is the 'record/playback' type. For example, a tester could click through all combinations of menu choices, dialog box choices, buttons, etc. in an application GUI and have them 'recorded' and the results logged by a tool. The 'recording' is typically in the form of text based on a scripting language that is interpretable by the testing tool. If new buttons are added, or some underlying code in the application is changed, etc. the application can then be retested by just 'playing back' the 'recorded' actions, and comparing the logging results to check effects of the changes. The problem with such tools is that if there are continual changes to the system being tested, the 'recordings' may have to be changed so much that it becomes very time-consuming to continuously update the scripts. Additionally, interpretation of results (screens, data, logs, etc.) can be a difficult task. Note that there are record/playback tools for text-based interfaces also, and for all types of platforms.
• Other automated tools can include:

       code analyzers - monitor code complexity, adherence to
                        standards, etc.
  
       coverage analyzers - these tools check which parts of the
                        code have been exercised by a test, and may
                        be oriented to code statement coverage,
                        condition coverage, path coverage, etc.
  
       memory analyzers - such as bounds-checkers and leak detectors.
  
       load/performance test tools - for testing client/server
                        and web applications under various load
                        levels.
  
       web test tools - to check that links are valid, HTML code
                        usage is correct, client-side and
                        server-side programs work, a web site's
                        interactions are secure.
                                           
       other tools - for test case management, documentation
                        management, bug reporting, and configuration
                        management.
  

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© 1996-2000 by Rick Hower
Last revised: 1/2/2000