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'.
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'.
Does every software project need testers?
While all projects will benefit from testing, some projects may not require independent test staff to succeed.
Which projects may not need independent test staff? The answer depends on the size and context of the project, the risks, the development methodology, the skill and experience of the developers, and other factors. For instance, if the project is a short-term, small, low risk project, with highly experienced programmers utilizing thorough unit testing or test-first development, then test engineers may not be required for the project to succeed.
In some cases an IT organization may be too small or new to have a testing staff even if the situation calls for it. In these circumstances it may be appropriate to instead use contractors or outsourcing, or adjust the project management and development approach (by switching to more senior developers and agile test-first development, for example). Inexperienced managers sometimes gamble on the success of a project by skipping thorough testing or having programmers do post-development functional testing of their own work, a decidedly high risk gamble.
For non-trivial-size projects or projects with non-trivial risks, a testing staff is usually necessary. As in any business, the use of personnel with specialized skills enhances an organization's ability to be successful in large, complex, or difficult tasks. It allows for both a) deeper and stronger skills and b) the contribution of differing perspectives. For example, programmers typically have the perspective of 'what are the technical issues in making this functionality work?'. A test engineer typically has the perspective of 'what might go wrong with this functionality, and how can we ensure it meets expectations?'. Technical people who can be highly effective in approaching tasks from both of those perspectives are rare, which is why, sooner or later, organizations bring in test specialists.
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.
What is a 'walkthrough'?
A 'walkthrough' is an informal meeting for evaluation or informational purposes. Little or no preparation is usually required.
What kinds of testing should be considered?
Quality software is reasonably bug-free, delivered on time and within budget, meets requirements and/or expectations, and is maintainable.
What is SEI? CMM? CMMI? ISO? IEEE? ANSI? Will it help?
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 1997-2001, 1018 organizations
were assessed. Of those, 27% were rated at Level 1, 39% at 2,
23% at 3, 6% at 4, and 5% 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.
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.
What makes a good Software 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 reviews.
What makes a good QA or Test manager?
A good QA, test, or QA/Test(combined) manager should:
What's the role of documentation in QA?
Critical. (Note that documentation can be electronic, not necessarily paper, may be embedded in code comments, etc.) 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 in some form. There should ideally be a system for easily finding and obtaining information and determining what documentation will have a particular piece of information. Change management for documentation should be used if possible.
What steps are needed to develop and run software tests?
The following are some of the steps to consider:
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:
What's a 'test case'?
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 . The following are items to consider in the tracking process:
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/
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:
What if there isn't enough time for thorough testing?
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:
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 analysis.
How does a client/server environment affect testing?
Client/server applications can be quite complex due to the multiple dependencies among clients, data communications, hardware, and servers, especially in multi-tier systems. 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.
Who is responsible for risk management?
Risk management means the actions taken to avoid things going wrong on a software development project, things that might negatively impact the quality, timeliness, or cost of a project. This is, of course, a shared responsibility among everyone involved in a project. However, there needs to be a 'buck stops here' person who can consider the relevant tradeoffs when decisions are required, and who can ensure that everyone is handling their risk management responsibilities.
It is not unusual for the term 'risk management' to never come up at all in a software organization or project. If it does come up, it's often assumed to be the responsibility of QA or test personnel. Or there may be a 'risks' or 'issues' section of a project, QA, or test plan, and it's assumed that this means that risk management has taken place.
The issues here are similar to those for the LFAQ question "Who should decide when software is ready to be released?" It's generally NOT a good idea for a test lead, test manager, or QA manager to be the 'buck stops here' person for risk management. Typically QA/Test personnel or managers are not managers of developers, analysts, designers and many other project personnel, and so it would be difficult for them to ensure that everyone on a project is handling their risk management responsibilities. Additionally, knowledge of all the considerations that go into risk management mitigation and tradeoff decisions is rarely the province of QA/Test personnel or managers. Based on these factors, the project manager is usually the most appropriate 'buck stops here' risk management person. QA/Test personnel can, however, provide input to the project manager. Such input could include analysis of quality-related risks, risk monitoring, process adherence reporting, defect reporting, and other information.
Who should decide when software is ready to be released?
In many projects this depends on the release criteria for the software. Such criteria are often in turn based on the decision to end testing, discussed in FAQ #2 item "How can it be known when to stop testing?" Unfortunately, for any but the simplest software projects, it is nearly impossible to adequately specify useful criteria without a significant amount of assumptions and subjectivity. For example, if the release criteria is based on passing a certain set of tests, there is likely an assumption that the tests have adequately addressed all appropriate software risks. For most software projects, this would of course be impossible without enormous expense, so this assumption would be a large leap of faith. Additionally, since most software projects involve a balance of quality, timeliness, and cost, testing alone cannot address how to balance all three of these competing factors when release decisions are needed.
A typical approach is for a lead tester or QA or Test manager to be the release decision maker. This again involves significant assumptions - such as an assumption that the test manager understands the spectrum of considerations that are important in determining whether software quality is 'sufficient' for release, or the assumption that quality does not have to be balanced with timeliness and cost. In many organizations, 'sufficient quality' is not well defined, is extremely subjective, may have never been usefully discussed, or may vary from project to project or even from day to day.
Release criteria considerations can include deadlines, sales goals, business/market/competitive considerations, business segment quality norms, legal requirements, technical and programming considerations, end-user expectations, internal budgets, impacts on other organization projects or goals, and a variety of other factors. Knowledge of all these factors is often shared among a number of personnel in a large organization, such as the project manager, director, customer service manager, technical lead or manager, marketing manager, QA manager, etc. In smaller organizations or projects it may be appropriate for one person to be knowledgeable in all these areas, but that person is typically a project manager, not a test lead or QA manager.
For these reasons, it's generally not a good idea for a test lead, test manager, or QA manager to decide when software is ready to be released. Their responsibility should be to provide input to the appropriate person or group that makes a release decision. For small organizations and projects that person could be a product manager, a project manager, or similar manager. For larger organizations and projects, release decisions might be made by a committee of personnel with sufficient collective knowledge of the relevant considerations.
What can be done if requirements are changing continuously?
This is a common problem for organizations where there are expectations that requirements can be pre-determined and remain stable. If these expectations are reasonable, here are some approaches:
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 could 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 the functionality is minor and low risk then no action may be necessary.) If not removed, information will be needed to determine risks and to determine any added testing needs or regression testing needs. Management should be made aware of any significant added risks as a result of the unexpected functionality.
This problem is a standard aspect of projects that include COTS (Commercial Off-The-Shelf) software or modified COTS software. The COTS part of the project will typically have a large amount of functionality that is not included in project requirements, or may be simply undetermined. Depending on the situation, it may be appropriate to perform in-depth analysis of the COTS software and work closely with the end user to determine which pre-existing COTS functionality is important and which functionality may interact with or be affected by the non-COTS aspects of the project. A significant regression testing effort may be needed (again, depending on the situation), and automated regression testing may be useful.
How can Software QA processes be implemented without reducing productivity?
By implementing QA processes slowly over time, using consensus to reach agreement on processes, focusing on processes that align tightly with organizational goals, and adjusting/experimenting/
Other possibilities include incremental self-managed team approaches such as 'Kaizen' methods of continuous process improvement, the Deming-Shewhart Plan-Do-Check-Act cycle, and others.
Will automated testing tools make testing easier?
What's the best way to choose a test automation tool?
It's easy to get caught up in enthusiasm for the 'silver bullet' of test automation, where the dream is that a single mouse click can initialize thorough unattended testing of an entire software application, bugs will be automatically reported, and easy-to-understand summary reports will be waiting in the manager's in-box in the morning.
Although that may in fact be possible in some situations, it is not the way things generally play out.
In manual testing, the test engineer exercises software functionality to determine if the software is behaving in an expected way. This means that the tester must be able to judge what the expected outcome of a test should be, such as expected data outputs, screen messages, changes in the appearance of a User Interface, XML files, database changes, etc. In an automated test, the computer does not have human-like 'judgement' capabilities to determine whether or not a test outcome was correct. This means there must be a mechanism by which the computer can do an automatic comparison between actual and expected results for every automated test scenario and unambiguously make a pass or fail determination. This factor may require a significant change in the entire approach to testing, since in manual testing a human is involved and can:
Once a short list of potential test tools is selected, several can be utilized on a trial basis for a final determination. Any expensive test tool should be thoroughly analyzed during its trial period to ensure that it is appropriate and that it's capabilities and limitations are well understood. This may require significant time or training, but the alternative is to take a major risk of a mistaken investment.
What's the best approach to estimating test efforts?
There is no simple answer for this. The 'best approach' is highly dependent on the particular organization and project and the experience of the personnel involved.
For example, given two software projects of similar complexity and size, the appropriate test effort for one project might be very large if it was for life-critical medical equipment software, but might be much smaller for the other project if it was for a low-cost computer game. A test estimation approach that only considered size and complexity might be appropriate for one project but not for the other. Following are some approaches to consider.
Implicit Risk Context Approach:
A typical approach to test estimation is for a project manager or QA manager to implicitly use risk context, in combination with past personal experiences in the organization, to choose a level of resources to allocate to testing. In many organizations, the 'risk context' is assumed to be similar from one project to the next, so there is no explicit consideration of risk context. (Risk context might include factors such as the organization's typical software quality levels, the software's intended use, the experience level of developers and testers, etc.) This is essentially an intuitive guess based on experience.
Metrics-Based Approach:
A useful approach is to track past experience of an organization's various projects and the associated test effort that worked well for projects. Once there is a set of data covering characteristics for a reasonable number of projects, then this 'past experience' information can be used for future test project planning. (Determining and collecting useful project metrics over time can be an extremely difficult task.) For each particular new project, the 'expected' required test time can be adjusted based on whatever metrics or other information is available, such as function point count, number of external system interfaces, unit testing done by developers, risk levels of the project, etc. In the end, this is essentially 'judgement based on documented experience', and is not easy to do successfully.
Test Work Breakdown Approach:
Another common approach is to decompose the expected testing tasks into a collection of small tasks for which estimates can, at least in theory, be made with reasonable accuracy. This of course assumes that an accurate and predictable breakdown of testing tasks and their estimated effort is feasible. In many large projects, this is not the case. For example, if a large number of bugs are being found in a project, this will add to the time required for testing, retesting, bug analysis and reporting. It will also add to the time required for development, and if development schedules and efforts do not go as planned, this will further impact testing.
Iterative Approach:
In this approach for large test efforts, an initial rough testing estimate is made. Once testing begins, a more refined estimate is made after a small percentage (eg, 1%) of the first estimate's work is done. At this point testers have obtained additional test project knowledge and a better understanding of issues, general software quality, and risk. Test plans and schedules can be refactored if necessary and a new estimate provided. Then a yet-more-refined estimate is made after a somewhat larger percentage (eg, 2%) of the new work estimate is done. Repeat the cycle as necessary/appropriate.
Percentage-of-Development Approach:
Some organizations utilize a quick estimation method for testing based on the estimated programming effort. For example, if a project is estimated to require 1000 hours of programming effort, and the organization normally finds that a 40% ratio for testing is appropriate, then an estimate of 400 hours for testing would be used. This approach may or may not be useful depending on the project-to-project variations in risk, personnel, types of applications, levels of complexity, etc.
Successful test estimation is a challenge for most organizations, since few can accurately estimate software project development efforts, much less the testing effort of a project. It is also difficult to attempt testing estimates without first having detailed information about a project, including detailed requirements, the organization's experience with similar projects in the past, and an understanding of what should be included in a 'testing' estimation for a project (functional testing? unit testing? reviews? inspections? load testing? security testing?)
With agile software development approaches, test effort estimations may be unnecessary if pure test-driven development is utilized. In general, agile-based projects by their nature will not be heavily dependent on large testing efforts, since they emphasize the construction of releasable software in very short iteration cycles. Therefore test effort estimates may not be as difficult and the impact of inaccurate estimates will be minimized.
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.
Does every software project need testers? While all projects will benefit from testing, some projects may not require independent test staff to succeed.
Which projects may not need independent test staff? The answer depends on the size and context of the project, the risks, the development methodology, the skill and experience of the developers, and other factors. For instance, if the project is a short-term, small, low risk project, with highly experienced programmers utilizing thorough unit testing or test-first development, then test engineers may not be required for the project to succeed.
In some cases an IT organization may be too small or new to have a testing staff even if the situation calls for it. In these circumstances it may be appropriate to instead use contractors or outsourcing, or adjust the project management and development approach (by switching to more senior developers and agile test-first development, for example). Inexperienced managers sometimes gamble on the success of a project by skipping thorough testing or having programmers do post-development functional testing of their own work, a decidedly high risk gamble.
For non-trivial-size projects or projects with non-trivial risks, a testing staff is usually necessary. As in any business, the use of personnel with specialized skills enhances an organization's ability to be successful in large, complex, or difficult tasks. It allows for both a) deeper and stronger skills and b) the contribution of differing perspectives. For example, programmers typically have the perspective of 'what are the technical issues in making this functionality work?'. A test engineer typically has the perspective of 'what might go wrong with this functionality, and how can we ensure it meets expectations?'. Technical people who can be highly effective in approaching tasks from both of those perspectives are rare, which is why, sooner or later, organizations bring in test specialists.
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.
What is a 'walkthrough'?
A 'walkthrough' is an informal meeting for evaluation or informational purposes. Little or no preparation is usually required.
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 or smoke testing - typically an initial testing effort to determine if a new software version is performing well enough to accept it for a major testing effort. For example, if the new software is crashing systems every 5 minutes, bogging down systems to a crawl, or corrupting databases, the software may not be in a 'sane' enough condition to warrant further testing in its current state.
- regression testing - re-testing after fixes or modifications of the software or its environment. It can be difficult to determine how much re-testing is needed, especially near the end of the development cycle. Automated testing 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 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.
- failover testing - typically used interchangeably with 'recovery testing'
- security testing - testing how well the system protects against unauthorized internal or external access, willful damage, etc; may require sophisticated testing techniques.
- compatability testing - testing how well software performs in a particular hardware/software/operating system/network/etc. environment.
- exploratory testing - often taken to mean a creative, informal software test that is not based on formal test plans or test cases; testers may be learning the software as they test it.
- ad-hoc testing - similar to exploratory testing, but often taken to mean that the testers have significant understanding of the software before testing it.
- context-driven testing - testing driven by an understanding of the environment, culture, and intended use of software. For example, the testing approach for life-critical medical equipment software would be completely different than that for a low-cost computer game.
- user acceptance testing - determining if software is satisfactory to an end-user or customer.
- comparison testing - comparing software weaknesses and strengths to competing products.
- alpha testing - testing of an application when development is nearing completion; minor design changes may still be made as a result of such testing. Typically done by end-users or others, not by programmers or testers.
- beta testing - testing when development and testing are essentially completed and final bugs and problems need to be found before final release. Typically done by end-users or others, not by programmers or testers.
- mutation testing - a method for determining if a set of test data or test cases is useful, by deliberately introducing various code changes ('bugs') and retesting with the original test data/cases to determine if the 'bugs' are detected. Proper implementation requires large computational resources.
Quality software is reasonably bug-free, delivered on time and within budget, meets requirements and/or expectations, and is maintainable.
What is SEI? CMM? CMMI? ISO? IEEE? ANSI? Will it help? - SEI = 'Software Engineering Institute' at Carnegie-Mellon University; initiated by the U.S. Defense Department to help improve software development processes.
- CMM = 'Capability Maturity Model', now called the CMMI ('Capability Maturity Model Integration'), developed by the SEI. It's a model of 5 levels of process '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 CMMI ratings by undergoing assessments by qualified auditors.
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 1997-2001, 1018 organizations
were assessed. Of those, 27% were rated at Level 1, 39% at 2,
23% at 3, 6% at 4, and 5% 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/IT management process assessment methods besides CMMI and ISO 9000 include SPICE, Trillium, TickIT, Bootstrap, ITIL, MOF, and CobiT.
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.
What makes a good Software 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 reviews.
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 adhered to
- have people judgement skills for hiring and keeping skilled personnel
- 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, may be embedded in code comments, etc.) 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 in some form. There should ideally be a system for easily finding and obtaining information and determining what documentation will have a particular piece of information. Change management for documentation should be used if possible.
What steps are needed to develop and run software tests? 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.)
- Determine project context, relative to the existing quality culture of the organization and business, and how it might impact testing scope, aproaches, and methods.
- 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 requirements
- Set schedule estimates, timelines, milestones
- Determine input equivalence classes, boundary value analyses, error classes
- Prepare test plan document and have needed reviews/approvals
- 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:
- Title
- Identification of software including version/release numbers
- Revision history of document including authors, dates, approvals
- 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 personnel/contact-info/
responsibilties - 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 applicable
- 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 control
- 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 issues
- Relevant proprietary, classified, security, and licensing issues.
- Open issues
- Appendix - glossary, acronyms, etc.
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 . 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', etc.)
- The application name or identifier and version
- The function, module, feature, object, screen, etc. where the bug occurred
- Environment specifics, system, platform, relevant hardware specifics
- 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 in test
- File excerpts/error messages/log file excerpts/screen shots/test tool logs that would be helpful in finding the cause of the problem
- 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 assigned to
- 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
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/
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 specified point - Bug rate falls below a certain level
- Beta or alpha testing period ends
What if there isn't enough time for thorough testing? 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 intended purpose?
- Which functionality is most visible to the user?
- Which functionality has the largest safety impact?
- Which functionality has the largest financial impact on users?
- Which aspects of the application are most important to the customer?
- 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 panic mode?
- Which aspects of similar/related previous projects caused problems?
- 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 service complaints?
- What kinds of tests could easily cover multiple functionalities?
- Which tests will have the best high-risk-coverage to time-required ratio?
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 analysis.
How does a client/server environment affect testing?
Client/server applications can be quite complex due to the multiple dependencies among clients, data communications, hardware, and servers, especially in multi-tier systems. 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.
Who is responsible for risk management? Risk management means the actions taken to avoid things going wrong on a software development project, things that might negatively impact the quality, timeliness, or cost of a project. This is, of course, a shared responsibility among everyone involved in a project. However, there needs to be a 'buck stops here' person who can consider the relevant tradeoffs when decisions are required, and who can ensure that everyone is handling their risk management responsibilities.
It is not unusual for the term 'risk management' to never come up at all in a software organization or project. If it does come up, it's often assumed to be the responsibility of QA or test personnel. Or there may be a 'risks' or 'issues' section of a project, QA, or test plan, and it's assumed that this means that risk management has taken place.
The issues here are similar to those for the LFAQ question "Who should decide when software is ready to be released?" It's generally NOT a good idea for a test lead, test manager, or QA manager to be the 'buck stops here' person for risk management. Typically QA/Test personnel or managers are not managers of developers, analysts, designers and many other project personnel, and so it would be difficult for them to ensure that everyone on a project is handling their risk management responsibilities. Additionally, knowledge of all the considerations that go into risk management mitigation and tradeoff decisions is rarely the province of QA/Test personnel or managers. Based on these factors, the project manager is usually the most appropriate 'buck stops here' risk management person. QA/Test personnel can, however, provide input to the project manager. Such input could include analysis of quality-related risks, risk monitoring, process adherence reporting, defect reporting, and other information.
Who should decide when software is ready to be released? In many projects this depends on the release criteria for the software. Such criteria are often in turn based on the decision to end testing, discussed in FAQ #2 item "How can it be known when to stop testing?" Unfortunately, for any but the simplest software projects, it is nearly impossible to adequately specify useful criteria without a significant amount of assumptions and subjectivity. For example, if the release criteria is based on passing a certain set of tests, there is likely an assumption that the tests have adequately addressed all appropriate software risks. For most software projects, this would of course be impossible without enormous expense, so this assumption would be a large leap of faith. Additionally, since most software projects involve a balance of quality, timeliness, and cost, testing alone cannot address how to balance all three of these competing factors when release decisions are needed.
A typical approach is for a lead tester or QA or Test manager to be the release decision maker. This again involves significant assumptions - such as an assumption that the test manager understands the spectrum of considerations that are important in determining whether software quality is 'sufficient' for release, or the assumption that quality does not have to be balanced with timeliness and cost. In many organizations, 'sufficient quality' is not well defined, is extremely subjective, may have never been usefully discussed, or may vary from project to project or even from day to day.
Release criteria considerations can include deadlines, sales goals, business/market/competitive considerations, business segment quality norms, legal requirements, technical and programming considerations, end-user expectations, internal budgets, impacts on other organization projects or goals, and a variety of other factors. Knowledge of all these factors is often shared among a number of personnel in a large organization, such as the project manager, director, customer service manager, technical lead or manager, marketing manager, QA manager, etc. In smaller organizations or projects it may be appropriate for one person to be knowledgeable in all these areas, but that person is typically a project manager, not a test lead or QA manager.
For these reasons, it's generally not a good idea for a test lead, test manager, or QA manager to decide when software is ready to be released. Their responsibility should be to provide input to the appropriate person or group that makes a release decision. For small organizations and projects that person could be a product manager, a project manager, or similar manager. For larger organizations and projects, release decisions might be made by a committee of personnel with sufficient collective knowledge of the relevant considerations.
What can be done if requirements are changing continuously? This is a common problem for organizations where there are expectations that requirements can be pre-determined and remain stable. If these expectations are reasonable, here are some approaches:
- 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 some type of 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' version.
- 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 job.
- Balance the effort put into setting up automated testing with the expected effort required to refactor them to deal with changes.
- Try to design some flexibility into automated test scripts.
- 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 entails).
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 could 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 the functionality is minor and low risk then no action may be necessary.) If not removed, information will be needed to determine risks and to determine any added testing needs or regression testing needs. Management should be made aware of any significant added risks as a result of the unexpected functionality.
This problem is a standard aspect of projects that include COTS (Commercial Off-The-Shelf) software or modified COTS software. The COTS part of the project will typically have a large amount of functionality that is not included in project requirements, or may be simply undetermined. Depending on the situation, it may be appropriate to perform in-depth analysis of the COTS software and work closely with the end user to determine which pre-existing COTS functionality is important and which functionality may interact with or be affected by the non-COTS aspects of the project. A significant regression testing effort may be needed (again, depending on the situation), and automated regression testing may be useful.
How can Software QA processes be implemented without reducing productivity? By implementing QA processes slowly over time, using consensus to reach agreement on processes, focusing on processes that align tightly with organizational goals, and adjusting/experimenting/
Other possibilities include incremental self-managed team approaches such as 'Kaizen' methods of continuous process improvement, the Deming-Shewhart Plan-Do-Check-Act cycle, and others.
Will automated testing tools make testing easier? - Possibly. For small projects, the time needed to learn and implement them may not be worth it unless personnel are already familiar with the tools. 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. Often the recorded script is manually modified and enhanced. If new buttons are added, or some underlying code in the application is changed, etc. the application might 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 and analysis 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.
- Another common type of approach for automation of functional testing is 'data-driven' or 'keyword-driven' automated testing, in which the test drivers are separated from the data and/or actions utilized in testing (an 'action' would be something like 'enter a value in a text box'). Test drivers can be in the form of automated test tools or custom-written testing software. The data and actions can be more easily maintained - such as via a spreadsheet - since they are separate from the test drivers. The test drivers 'read' the data/action information to perform specified tests. This approach can enable more efficient control, development, documentation, and maintenance of automated tests/test cases.
- 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, file and database comparisons, screen
- captures, security testing, macro recorders, etc.
What's the best way to choose a test automation tool? It's easy to get caught up in enthusiasm for the 'silver bullet' of test automation, where the dream is that a single mouse click can initialize thorough unattended testing of an entire software application, bugs will be automatically reported, and easy-to-understand summary reports will be waiting in the manager's in-box in the morning.
Although that may in fact be possible in some situations, it is not the way things generally play out.
In manual testing, the test engineer exercises software functionality to determine if the software is behaving in an expected way. This means that the tester must be able to judge what the expected outcome of a test should be, such as expected data outputs, screen messages, changes in the appearance of a User Interface, XML files, database changes, etc. In an automated test, the computer does not have human-like 'judgement' capabilities to determine whether or not a test outcome was correct. This means there must be a mechanism by which the computer can do an automatic comparison between actual and expected results for every automated test scenario and unambiguously make a pass or fail determination. This factor may require a significant change in the entire approach to testing, since in manual testing a human is involved and can:
- make mental adjustments to expected test results based on variations in the pre-test state of the software system
- often make on-the-fly adjustments, if needed, to data used in the test
- make pass/fail judgements about results of each test
- make quick judgements and adjustments for changes to requirements.
- make a wide variety of other types of judgements and adjustments as needed.
- Analyze the current non-automated testing situation to determine where testing is not being done or does not appear to be sufficient
- Where is current testing excessively time-consuming?
- Where is current testing excessively tedious?
- What kinds of problems are repeatedly missed with current testing?
- What testing procedures are carried out repeatedly (such as regression testing or security testing)?
- What testing procedures are not being carried out repeatedly but should be?
- What test tracking and management processes can be implemented or made more effective through the use of an automated test tool?
Once a short list of potential test tools is selected, several can be utilized on a trial basis for a final determination. Any expensive test tool should be thoroughly analyzed during its trial period to ensure that it is appropriate and that it's capabilities and limitations are well understood. This may require significant time or training, but the alternative is to take a major risk of a mistaken investment.
What's the best approach to estimating test efforts? There is no simple answer for this. The 'best approach' is highly dependent on the particular organization and project and the experience of the personnel involved.
For example, given two software projects of similar complexity and size, the appropriate test effort for one project might be very large if it was for life-critical medical equipment software, but might be much smaller for the other project if it was for a low-cost computer game. A test estimation approach that only considered size and complexity might be appropriate for one project but not for the other. Following are some approaches to consider.
Implicit Risk Context Approach:
A typical approach to test estimation is for a project manager or QA manager to implicitly use risk context, in combination with past personal experiences in the organization, to choose a level of resources to allocate to testing. In many organizations, the 'risk context' is assumed to be similar from one project to the next, so there is no explicit consideration of risk context. (Risk context might include factors such as the organization's typical software quality levels, the software's intended use, the experience level of developers and testers, etc.) This is essentially an intuitive guess based on experience.
Metrics-Based Approach:
A useful approach is to track past experience of an organization's various projects and the associated test effort that worked well for projects. Once there is a set of data covering characteristics for a reasonable number of projects, then this 'past experience' information can be used for future test project planning. (Determining and collecting useful project metrics over time can be an extremely difficult task.) For each particular new project, the 'expected' required test time can be adjusted based on whatever metrics or other information is available, such as function point count, number of external system interfaces, unit testing done by developers, risk levels of the project, etc. In the end, this is essentially 'judgement based on documented experience', and is not easy to do successfully.
Test Work Breakdown Approach:
Another common approach is to decompose the expected testing tasks into a collection of small tasks for which estimates can, at least in theory, be made with reasonable accuracy. This of course assumes that an accurate and predictable breakdown of testing tasks and their estimated effort is feasible. In many large projects, this is not the case. For example, if a large number of bugs are being found in a project, this will add to the time required for testing, retesting, bug analysis and reporting. It will also add to the time required for development, and if development schedules and efforts do not go as planned, this will further impact testing.
Iterative Approach:
In this approach for large test efforts, an initial rough testing estimate is made. Once testing begins, a more refined estimate is made after a small percentage (eg, 1%) of the first estimate's work is done. At this point testers have obtained additional test project knowledge and a better understanding of issues, general software quality, and risk. Test plans and schedules can be refactored if necessary and a new estimate provided. Then a yet-more-refined estimate is made after a somewhat larger percentage (eg, 2%) of the new work estimate is done. Repeat the cycle as necessary/appropriate.
Percentage-of-Development Approach:
Some organizations utilize a quick estimation method for testing based on the estimated programming effort. For example, if a project is estimated to require 1000 hours of programming effort, and the organization normally finds that a 40% ratio for testing is appropriate, then an estimate of 400 hours for testing would be used. This approach may or may not be useful depending on the project-to-project variations in risk, personnel, types of applications, levels of complexity, etc.
Successful test estimation is a challenge for most organizations, since few can accurately estimate software project development efforts, much less the testing effort of a project. It is also difficult to attempt testing estimates without first having detailed information about a project, including detailed requirements, the organization's experience with similar projects in the past, and an understanding of what should be included in a 'testing' estimation for a project (functional testing? unit testing? reviews? inspections? load testing? security testing?)
With agile software development approaches, test effort estimations may be unnecessary if pure test-driven development is utilized. In general, agile-based projects by their nature will not be heavily dependent on large testing efforts, since they emphasize the construction of releasable software in very short iteration cycles. Therefore test effort estimates may not be as difficult and the impact of inaccurate estimates will be minimized.