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.
What are 5 common problems in the software development process?
poor requirements - if requirements are unclear, incomplete, too general, and 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.
What are 5 common solutions to software development problems?
solid requirements - clear, complete, detailed, cohesive, attainable, testable requirements that are agreed to by all players. Use prototypes to help nail down requirements. In 'agile'-type environments, continuous coordination with customers/end-users is necessary.
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. 'Early' testing ideally includes unit testing by developers and built-in testing and diagnostic capabilities.
stick to initial requirements as much as possible - be prepared to defend against excessive 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, work closely with customers/end-users to manage expectations. This will provide them a higher comfort level with their requirements decisions and minimize excessive 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 information/documentation is available and up-to-date - preferably electronic, not paper; promote teamwork and cooperation; use protoypes if possible to clarify customers' expectations.
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.
What is 'good code'?
'Good code' is code that works, is bug free, and is readable and maintainable. Some organizations have coding 'standards' that all developers are supposed to adhere to, but everyone has different ideas about what's best, or what is too many or too few rules. There are also various theories and metrics, such as McCabe Complexity metrics. It should be kept in mind that excessive use of standards and rules can stifle productivity and creativity. 'Peer reviews', 'buddy checks' code analysis tools, etc. can be used to check for problems and enforce standards.
For C and C++ coding, here are some typical ideas to consider in setting rules/standards; these may or may not apply to a particular situation:
minimize or eliminate use of global variables.
use descriptive function and method names - use both upper and lower case, avoid abbreviations, use as many characters as necessary to be adequately descriptive (use of more than 20 characters is not out of line); be consistent in naming conventions.
use descriptive variable names - use both upper and lower case, avoid abbreviations, use as many characters as necessary to be adequately descriptive (use of more than 20 characters is not out of line); be consistent in naming conventions.
function and method sizes should be minimized; less than 100 lines of code is good, less than 50 lines is preferable.
function descriptions should be clearly spelled out in comments preceding a function's code.
organize code for readability.
use whitespace generously - vertically and 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 code.
no matter how small, an application should include documentaion of the overall program function and flow (even a few paragraphs is better than nothing); or if possible a separate flow chart and detailed program documentation.
make extensive use of error handling procedures and status and error logging.
for C++, to minimize complexity and increase maintainability, avoid too many levels of inheritance in class heirarchies (relative to the size and complexity of the application). Minimize use of multiple inheritance, and minimize use of operator overloading (note that the Java programming language eliminates multiple inheritance and operator overloading.)
for C++, keep class methods small, less than 50 lines of code per method is preferable.
for C++, make liberal use of exception handlers
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.
For programs that have a user interface, it's often a good idea to assume that the end user will have little computer knowledge and may not read a user manual or even the on-line help; some common rules-of-thumb include:
the program should act in a way that least surprises the user
it should always be evident to the user what can be done next and how to exit
the program shouldn't let the users do something stupid without warning them.
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.
Level 1 - characterized by chaos, periodic panics, and heroic
efforts required by individuals to successfully
complete projects. Few if any processes in place;
successes may not be repeatable.
Level 2 - software project tracking, requirements management,
realistic planning, and configuration management
processes are in place; successful practices can
be repeated.
Level 3 - standard software development and maintenance processes
are integrated throughout an organization; a Software
Engineering Process Group is is in place to oversee
software processes, and training programs are used to
ensure understanding and compliance.
Level 4 - metrics are used to track productivity, processes,
and products. Project performance is predictable,
and quality is consistently high.
Level 5 - the focus is on continouous process improvement. The
impact of new processes and technologies can be
predicted and effectively implemented when required.
Perspective on CMM ratings: During 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.
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.
Will automated testing tools make testing easier?
Possibly. For small projects, the time needed to learn and implement them may not be worth it. For larger projects, or on-going long-term projects they can be valuable.
A common type of automated tool is the 'record/playback' type. For example, a tester could click through all combinations of menu choices, dialog box choices, buttons, etc. in an application GUI and have them 'recorded' and the results logged by a tool. The 'recording' is typically in the form of text based on a scripting language that is interpretable by the testing tool. If new buttons are added, or some underlying code in the application is changed, etc. the application 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.
Testing Tools Interview Questions-3