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'.
- 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.
What are some recent major computer system
failures caused by software bugs?
- In March of 2002 it was reported that software bugs in Britain's
national tax system resulted in more than 100,000 erroneous tax
overcharges. The problem was partly attibuted to the difficulty of testing
the integration of multiple systems.
- A newspaper columnist reported in July 2001 that a
serious flaw was found in off-the-shelf software that had long been used
in systems for tracking certain U.S. nuclear materials. The
same software had been recently donated to another country to be used in
tracking their own nuclear materials, and it was not until scientists in
that country discovered the problem, and shared the information, that U.S.
officials became aware of the problems.
- According to newspaper stories in mid-2001, a major
systems development contractor was fired and sued over problems with a
large retirement plan management system. According to the reports, the
client claimed that system deliveries were late, the software had
excessive defects, and it caused other systems to crash.
- In January of 2001 newspapers reported that a major
European railroad was hit by the aftereffects of the Y2K bug. The company
found that many of their newer trains would not run due to their inability
to recognize the date '31/12/2000'; the trains were started by altering
the control system's date settings.
- News reports in September of 2000 told of a software
vendor settling a lawsuit with a large mortgage lender; the vendor had
reportedly delivered an online mortgage processing system that did not
meet specifications, was delivered late, and didn't work.
- In early 2000, major problems were reported with a new
computer system in a large suburban U.S. public school district with
100,000+ students; problems included 10,000 erroneous report cards and
students left stranded by failed class registration systems; the
district's CIO was fired. The school district decided to reinstate it's
original 25-year old system for at least a year until the bugs were worked
out of the new system by the software vendors.
- 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
- 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 its 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
- 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
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
- 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.'
- On June 4 1996 the first flight of the European Space
Agency's new Ariane 5 rocket failed shortly after launching, resulting in
an estimated uninsured loss of a half billion dollars. It was reportedly
due to the lack of exception handling of a floating-point error in a
conversion from a 64-bit integer to a 16-bit signed integer.
- 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.
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."
Why does software have bugs?
- miscommunication or no communication - as to specifics of
what an application should or shouldn't do (the application's
- 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
- 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:
·'piece of cake'
·'I can whip that out in a few hours'
·'it should be easy to update that old code'
·'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.
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 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,
- In all cases the most value for effort will be in
requirements management processes, with a goal of clear, complete,
testable requirement specifications or expectations.
(See the Bookstore section's 'Software QA', 'Software
Engineering', and 'Project Management' categories for useful books with more
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
What is a 'walkthrough'?
A 'walkthrough' is an informal meeting for evaluation or informational
purposes. Little or no preparation is usually required.
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 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.
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
- 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
- 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 '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
- 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.
- 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.
- 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
- 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
(See the Bookstore section's 'Software Testing' category for
useful books on Software Testing.)
What are 5 common problems in the software
- 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.
(See the Bookstore section's 'Software QA', 'Software
Engineering', and 'Project Management' categories for useful books with more
What are 5 common solutions to software
- 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
(See the Bookstore section's 'Software QA', 'Software
Engineering', and 'Project Management' categories for useful books with more
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.)
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
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 horizontally
- 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
- 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
- for C++, keep class methods small, less than 50 lines of
code per method is preferable.
- for C++, make liberal use of exception handlers
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
- the program should act in a way that least surprises the
- 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.
What is SEI? CMM? ISO? IEEE? ANSI? Will it
- 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
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 1997-2001, 1018 organizations
were assessed.Of those, 27% were rated at Level 1, 39% at 2,
23% at 3, 6% at 4, and5% at 5.(For ratings during the period
1992-96, 62% were 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; 32% of organizations were
U.S. federal contractors or agencies.For those rated at
Level 1, the most problematical key process area was in
Software Quality Assurance.
- ISO = 'International Organisation for Standardization' -
The ISO 9001:2000 standard (which replaces the previous standard of 1994)
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)Q9001-2000 - Quality Management Systems:
Requirements; (b)Q9000-2000 - Quality Management Systems: Fundamentals and
Vocabulary; (c)Q9004-2000 - Quality Management Systems: Guidelines for
Performance Improvements. 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. Also see http://www.iso.ch/ for the latest
information. In the U.S.
the standards can be purchased via the ASQ web site at http://e-standards.asq.org/
- 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.
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
Will automated testing tools make testing
- 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
·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
·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
What makes a
good test engineer?
A good test engineer has a 'test to break' attitude, an ability to take the
point of view of the customer, a strong desire for quality, and an attention to
detail. Tact and diplomacy are useful in maintaining a cooperative relationship
with developers, and an ability to communicate with both technical (developers)
and non-technical (customers, management) people is useful. Previous software
development experience can be helpful as it provides a deeper understanding of
the software development process, gives the tester an appreciation for the
developers' point of view, and reduce the learning curve in automated test tool
programming. Judgement skills are needed to assess high-risk areas of an
application on which to focus testing efforts when time is limited.
What makes a good Software QA engineer?
The same qualities a good tester has are useful for a QA engineer.
Additionally, they must be able to understand the entire software development
process and how it can fit into the business approach and goals of the
organization. Communication skills and the ability to understand various sides
of issues are important. In organizations in the early stages of implementing
QA processes, patience and diplomacy are especially needed. An ability to find
problems as well as to see 'what's missing' is important for inspections and
What makes a good QA or Test manager?
A good QA, test, or QA/Test(combined) manager should:
- be familiar with the software development process
- be able to maintain enthusiasm of their team and promote
a positive atmosphere, despite what is a somewhat 'negative' process
(e.g., looking for or preventing problems)
- be able to promote teamwork to increase productivity
- be able to promote cooperation between software, test,
and QA engineers
- have the diplomatic skills needed to promote improvements
in QA processes
- have the ability to withstand pressures and say 'no' to
other managers when quality is insufficient or QA processes are not being
- have people judgement skills for hiring and keeping
- be able to communicate with technical and non-technical
people, engineers, managers, and customers.
- be able to run meetings and keep them focused
What's the role of documentation in QA?
Critical. (Note that documentation can be electronic, not necessarily paper.)
QA practices should be documented such that they are repeatable.
Specifications, designs, business rules, inspection reports, configurations,
code changes, test plans, test cases, bug reports, user manuals, etc. should
all be documented. There should ideally be a system for easily finding and
obtaining documents and determining what documentation will have a particular
piece of information. Change management for documentation should be used if
What's the big deal about 'requirements'?
One of the most reliable methods of insuring problems, or failure, in a complex
software project is to have poorly documented requirements specifications.
Requirements are the details describing an application's externally-perceived
functionality and properties. Requirements should be clear, complete,
reasonably detailed, cohesive, attainable, and testable. A non-testable
requirement would be, for example, 'user-friendly' (too subjective). A testable
requirement would be something like 'the user must enter their previously-assigned
password to access the application'. Determining and organizing requirements
details in a useful and efficient way can be a difficult effort; different
methods are available depending on the particular project. Many books are
available that describe various approaches to this task. (See the Bookstore section's 'Software Requirements Engineering'
category for books on Software Requirements.)
Care should be taken to involve
ALL of a project's significant 'customers' in the requirements process.
'Customers' could be in-house personnel or out, and could include end-users,
customer acceptance testers, customer contract officers, customer management,
future software maintenance engineers, salespeople, etc. Anyone who could later
derail the project if their expectations aren't met should be included if
Organizations vary considerably in
their handling of requirements specifications. Ideally, the requirements are
spelled out in a document with statements such as 'The product shall.....'.
'Design' specifications should not be confused with 'requirements'; design
specifications should be traceable back to the requirements.
In some organizations requirements
may end up in high level project plans, functional specification documents, in
design documents, or in other documents at various levels of detail. No matter
what they are called, some type of documentation with detailed requirements
will be needed by testers in order to properly plan and execute tests. Without
such documentation, there will be no clear-cut way to determine if a software
application is performing correctly.
What steps are needed to develop and run
The following are some of the steps to consider:
- Obtain requirements, functional design, and internal
design specifications and other necessary documents
- Obtain budget and schedule requirements
- Determine project-related personnel and their
responsibilities, reporting requirements, required standards and processes
(such as release processes, change processes, etc.)
- Identify application's higher-risk aspects, set
priorities, and determine scope and limitations of tests
- Determine test approaches and methods - unit,
integration, functional, system, load, usability tests, etc.
- Determine test environment requirements (hardware,
software, communications, etc.)
- Determine testware requirements (record/playback tools,
coverage analyzers, test tracking, problem/bug tracking, etc.)
- Determine test input data requirements
- Identify tasks, those responsible for tasks, and labor
- Set schedule estimates, timelines, milestones
- Determine input equivalence classes, boundary value
analyses, error classes
- Prepare test plan document and have needed
- Write test cases
- Have needed reviews/inspections/approvals of test cases
- Prepare test environment and testware, obtain needed user
manuals/reference documents/configuration guides/installation guides, set
up test tracking processes, set up logging and archiving processes, set up
or obtain test input data
- Obtain and install software releases
- Perform tests
- Evaluate and report results
- Track problems/bugs and fixes
- Retest as needed
- Maintain and update test plans, test cases, test
environment, and testware through life cycle
What's a 'test plan'?
A software project test plan is a document that describes the objectives,
scope, approach, and focus of a software testing effort. The process of
preparing a test plan is a useful way to think through the efforts needed to
validate the acceptability of a software product. The completed document will
help people outside the test group understand the 'why' and 'how' of product
validation. It should be thorough enough to be useful but not so thorough that
no one outside the test group will read it. The following are some of the items
that might be included in a test plan, depending on the particular project:
- Identification of software including version/release
- Revision history of document including authors, dates,
- Table of Contents
- Purpose of document, intended audience
- Objective of testing effort
- Software product overview
- Relevant related document list, such as requirements,
design documents, other test plans, etc.
- Relevant standards or legal requirements
- Traceability requirements
- Relevant naming conventions and identifier conventions
- Overall software project organization and
- Test organization and personnel/contact-info/responsibilities
- Assumptions and dependencies
- Project risk analysis
- Testing priorities and focus
- Scope and limitations of testing
- Test outline - a decomposition of the test approach by
test type, feature, functionality, process, system, module, etc. as
- Outline of data input equivalence classes, boundary value
analysis, error classes
- Test environment - hardware, operating systems, other
required software, data configurations, interfaces to other systems
- Test environment validity analysis - differences between
the test and production systems and their impact on test validity.
- Test environment setup and configuration issues
- Software migration processes
- Software CM processes
- Test data setup requirements
- Database setup requirements
- Outline of system-logging/error-logging/other
capabilities, and tools such as screen capture software, that will be used
to help describe and report bugs
- Discussion of any specialized software or hardware tools
that will be used by testers to help track the cause or source of bugs
- Test automation - justification and overview
- Test tools to be used, including versions, patches, etc.
- Test script/test code maintenance processes and version
- Problem tracking and resolution - tools and processes
- Project test metrics to be used
- Reporting requirements and testing deliverables
- Software entrance and exit criteria
- Initial sanity testing period and criteria
- Test suspension and restart criteria
- Personnel allocation
- Personnel pre-training needs
- Test site/location
- Outside test organizations to be utilized and their
purpose, responsibilties, deliverables, contact persons, and coordination
- Relevant proprietary, classified, security, and licensing
- Open issues
- Appendix - glossary, acronyms, etc.
(See the Bookstore section's 'Software Testing' and 'Software
QA' categories for useful books with more information.)
What's a 'test case'?
- A test case is a document that describes an input,
action, or event and an expected response, to determine if a feature of an
application is working correctly. A test case should contain particulars
such as test case identifier, test case name, objective, test
conditions/setup, input data requirements, steps, and expected results.
- Note that the process of developing test cases can help
find problems in the requirements or design of an application, since it
requires completely thinking through the operation of the application. For
this reason, it's useful to prepare test cases early in the development
cycle if possible.
What should be done after a bug is found?
The bug needs to be communicated and assigned to developers that can fix it.
After the problem is resolved, fixes should be re-tested, and determinations
made regarding requirements for regression testing to check that fixes didn't
create problems elsewhere. If a problem-tracking system is in place, it should
encapsulate these processes. A variety of commercial
problem-tracking/management software tools are available (see the 'Tools' section for web resources with listings of such
tools). The following are items to consider in the tracking process:
- Complete information such that developers can understand
the bug, get an idea of it's severity, and reproduce it if necessary.
- Bug identifier (number, ID, etc.)
- Current bug status (e.g., 'Released for Retest', 'New',
- The application name or identifier and version
- The function, module, feature, object, screen, etc. where
the bug occurred
- Environment specifics, system, platform, relevant
- Test case name/number/identifier
- One-line bug description
- Full bug description
- Description of steps needed to reproduce the bug if not
covered by a test case or if the developer doesn't have easy access to the
test case/test script/test tool
- Names and/or descriptions of file/data/messages/etc. used
- File excerpts/error messages/log file excerpts/screen
shots/test tool logs that would be helpful in finding the cause of the
- Severity estimate (a 5-level range such as 1-5 or
'critical'-to-'low' is common)
- Was the bug reproducible?
- Tester name
- Test date
- Bug reporting date
- Name of developer/group/organization the problem is
- Description of problem cause
- Description of fix
- Code section/file/module/class/method that was fixed
- Date of fix
- Application version that contains the fix
- Tester responsible for retest
- Retest date
- Retest results
- Regression testing requirements
- Tester responsible for regression tests
- Regression testing results
A reporting or
tracking process should enable notification of appropriate personnel at various
stages. For instance, testers need to know when retesting is needed, developers
need to know when bugs are found and how to get the needed information, and
reporting/summary capabilities are needed for managers.
What is 'configuration management'?
Configuration management covers the processes used to control, coordinate, and
track: code, requirements, documentation, problems, change requests, designs,
tools/compilers/libraries/patches, changes made to them, and who makes the
changes. (See the 'Tools' section for web resources
with listings of configuration management tools. Also see the Bookstore section's 'Configuration Management' category
for useful books with more information.)
What if the software is so buggy it can't
really be tested at all?
The best bet in this situation is for the testers to go through the process of
reporting whatever bugs or blocking-type problems initially show up, with the
focus being on critical bugs. Since this type of problem can severely affect
schedules, and indicates deeper problems in the software development process
(such as insufficient unit testing or insufficient integration testing, poor
design, improper build or release procedures, etc.) managers should be
notified, and provided with some documentation as evidence of the problem.
How can it be known when to stop testing?
This can be difficult to determine. Many modern software applications are so
complex, and run in such an interdependent environment, that complete testing
can never be done. Common factors in deciding when to stop are:
- Deadlines (release deadlines, testing deadlines, etc.)
- Test cases completed with certain percentage passed
- Test budget depleted
- Coverage of code/functionality/requirements reaches a
- Bug rate falls below a certain level
- Beta or alpha testing period ends
What if there isn't enough time for
Use risk analysis to determine where testing should be focused.
Since it's rarely possible to test every possible aspect of an application,
every possible combination of events, every dependency, or everything that
could go wrong, risk analysis is appropriate to most software development
projects. This requires judgement skills, common sense, and experience. (If
warranted, formal methods are also available.) Considerations can include:
- Which functionality is most important to the project's
- Which functionality is most visible to the user?
- Which functionality has the largest safety impact?
- Which functionality has the largest financial impact on
- Which aspects of the application are most important to
- Which aspects of the application can be tested early in
the development cycle?
- Which parts of the code are most complex, and thus most
subject to errors?
- Which parts of the application were developed in rush or
- Which aspects of similar/related previous projects caused
- Which aspects of similar/related previous projects had
large maintenance expenses?
- Which parts of the requirements and design are unclear or
poorly thought out?
- What do the developers think are the highest-risk aspects
of the application?
- What kinds of problems would cause the worst publicity?
- What kinds of problems would cause the most customer
- What kinds of tests could easily cover multiple
- Which tests will have the best high-risk-coverage to
What if the project isn't big enough to
justify extensive testing?
Consider the impact of project errors, not the size of the project. However, if
extensive testing is still not justified, risk analysis is again needed and the
same considerations as described previously in 'What
if there isn't enough time for thorough testing?' apply. The tester might
then do ad hoc testing, or write up a limited test plan based on the risk
What can be done if requirements are
A common problem and a major headache.
- Work with the project's stakeholders early on to
understand how requirements might change so that alternate test plans and
strategies can be worked out in advance, if possible.
- It's helpful if the application's initial design allows
for some adaptability so that later changes do not require redoing the
application from scratch.
- If the code is well-commented and well-documented this
makes changes easier for the developers.
- Use rapid prototyping whenever possible to help customers
feel sure of their requirements and minimize changes.
- The project's initial schedule should allow for some
extra time commensurate with the possibility of changes.
- Try to move new requirements to a 'Phase 2' version of an
application, while using the original requirements for the 'Phase 1'
- Negotiate to allow only easily-implemented new
requirements into the project, while moving more difficult new
requirements into future versions of the application.
- Be sure that customers and management understand the
scheduling impacts, inherent risks, and costs of significant requirements
changes. Then let management or the customers (not the developers or
testers) decide if the changes are warranted - after all, that's their
- Balance the effort put into setting up automated testing
with the expected effort required to re-do them to deal with changes.
- Try to design some flexibility into automated test
- Focus initial automated testing on application aspects
that are most likely to remain unchanged.
- Devote appropriate effort to risk analysis of changes to
minimize regression testing needs.
- Design some flexibility into test cases (this is not
easily done; the best bet might be to minimize the detail in the test
cases, or set up only higher-level generic-type test plans)
- Focus less on detailed test plans and test cases and more
on ad hoc testing (with an understanding of the added risk that this
Also see What
is Extreme Programming and what's it got to do with testing? elsewhere in
the Softwareqatest.com FAQ.
What if the application has functionality
that wasn't in the requirements?
It may take serious effort to determine if an application has significant
unexpected or hidden functionality, and it would indicate deeper problems in
the software development process. If the functionality isn't necessary to the
purpose of the application, it should be removed, as it may have unknown
impacts or dependencies that were not taken into account by the designer or the
customer. If not removed, design information will be needed to determine added
testing needs or regression testing needs. Management should be made aware of
any significant added risks as a result of the unexpected functionality. If the
functionality only effects areas such as minor improvements in the user
interface, for example, it may not be a significant risk.
Software QA processes be implemented without stifling productivity?
By implementing QA processes slowly over time, using consensus to reach
agreement on processes, and adjusting and experimenting as an organization
grows and matures, productivity will be improved instead of stifled. Problem
prevention will lessen the need for problem detection, panics and burn-out will
decrease, and there will be improved focus and less wasted effort. At the same
time, attempts should be made to keep processes simple and efficient, minimize
paperwork, promote computer-based processes and automated tracking and
reporting, minimize time required in meetings, and promote training as part of
the QA process. However, no one - especially talented technical types - likes
rules or bureacracy, and in the short run things may slow down a bit. A typical
scenario would be that more days of planning and development will be needed,
but less time will be required for late-night bug-fixing and calming of irate
(See the Bookstore section's 'Software QA',
'Software Engineering', and 'Project Management' categories for useful books
with more information.)
What if an organization is growing so fast
that fixed QA processes are impossible?
This is a common problem in the software industry, especially in new technology
areas. There is no easy solution in this situation, other than:
- Hire good people
- Management should 'ruthlessly prioritize' quality issues
and maintain focus on the customer
- Everyone in the organization should be clear on what
'quality' means to the customer
How does a client/server environment affect
Client/server applications can be quite complex due to the multiple dependencies
among clients, data communications, hardware, and servers. Thus testing
requirements can be extensive. When time is limited (as it usually is) the
focus should be on integration and system testing. Additionally,
load/stress/performance testing may be useful in determining client/server
application limitations and capabilities. There are commercial tools to assist
with such testing. (See the 'Tools' section for web
resources with listings that include these kinds of test tools.)
How can World Wide Web sites be tested?
Web sites are essentially client/server applications - with web servers and
'browser' clients. Consideration should be given to the interactions between
html pages, TCP/IP communications, Internet connections, firewalls,
applications), and applications that run on the server side (such as cgi
scripts, database interfaces, logging applications, dynamic page generators,
asp, etc.). Additionally, there are a wide variety of servers and browsers,
various versions of each, small but sometimes significant differences between
them, variations in connection speeds, rapidly changing technologies, and
multiple standards and protocols. The end result is that testing for web sites
can become a major ongoing effort. Other considerations might include:
- What are the expected loads on the server (e.g., number
of hits per unit time?), and what kind of performance is required under
such loads (such as web server response time, database query response
times). What kinds of tools will be needed for performance testing (such
as web load testing tools, other tools already in house that can be
adapted, web robot downloading tools, etc.)?
- Who is the target audience? What kind of browsers will
they be using? What kind of connection speeds will they by using? Are they
intra- organization (thus with likely high connection speeds and similar
browsers) or Internet-wide (thus with a wide variety of connection speeds
and browser types)?
- What kind of performance is expected on the client side
(e.g., how fast should pages appear, how fast should animations, applets,
etc. load and run)?
- Will down time for server and content
maintenance/upgrades be allowed? how much?
- What kinds of security (firewalls, encryptions,
passwords, etc.) will be required and what is it expected to do? How can
it be tested?
- How reliable are the site's Internet connections required
to be? And how does that affect backup system or redundant connection
requirements and testing?
- What processes will be required to manage updates to the
web site's content, and what are the requirements for maintaining,
tracking, and controlling page content, graphics, links, etc.?
- Which HTML specification will be adhered to? How
strictly? What variations will be allowed for targeted browsers?
- Will there be any standards or requirements for page
appearance and/or graphics throughout a site or parts of a site??
- How will internal and external links be validated and
updated? how often?
- Can testing be done on the production system, or will a
separate test system be required? How are browser caching, variations in
browser option settings, dial-up connection variabilities, and real-world
internet 'traffic congestion' problems to be accounted for in testing?
- How extensive or customized are the server logging and
reporting requirements; are they considered an integral part of the system
and do they require testing?
components, etc. to be maintained, tracked, controlled, and tested?
Some sources of
site security information include the Usenet newsgroup 'comp.security.announce'
and links concerning web site security in
the 'Other Resources' section.
Some usability guidelines to
consider - these are subjective and may or may not apply to a given situation
(Note: more information on usability testing issues can be found in articles about web site usability in the
'Other Resources' section):
- Pages should be 3-5 screens max unless content is tightly
focused on a single topic. If larger, provide internal links within the
- The page layouts and design elements should be consistent
throughout a site, so that it's clear to the user that they're still
within a site.
- Pages should be as browser-independent as possible, or
pages should be provided or generated based on the browser-type.
- All pages should have links external to the page; there
should be no dead-end pages.
- The page owner, revision date, and a link to a contact
person or organization should be included on each page.
Many new web site
test tools are appearing and more than 230 of them are listed in the 'Web Test Tools' section.
How is testing affected by object-oriented
Well-engineered object-oriented design can make it easier to trace from code to
internal design to functional design to requirements. While there will be
little affect on black box testing (where an understanding of the internal
design of the application is unnecessary), white-box testing can be oriented to
the application's objects. If the application was well-designed this can
simplify test design.
What is Extreme Programming and what's it
got to do with testing?
Extreme Programming (XP) is a software development approach for small teams on
risk-prone projects with unstable requirements. It was created by Kent Beck who
described the approach in his book 'Extreme Programming Explained' (See the Softwareqatest.com Books page.). Testing
('extreme testing') is a core aspect of Extreme Programming. Programmers are
expected to write unit and functional test code first - before the application
is developed. Test code is under source control along with the rest of the
code. Customers are expected to be an integral part of the project team and to
help develope scenarios for acceptance/black box testing. Acceptance tests are
preferably automated, and are modified and rerun for each of the frequent
development iterations. QA and test personnel are also required to be an
integral part of the project team. Detailed requirements documentation is not
used, and frequent re-scheduling, re-estimating, and re-prioritizing is
expected. For more info see the XP-related listings in the Softwareqatest.com 'Other Resources' section.