1. What is Test Bed?
An execution environment configured for testing. May consist of specific hardware, OS, network topology, configuration of the product under test, other application or system software, etc. The Test Plan for a project should enumerated the test beds(s) to be used.
2. What is Test Case?
Test Case is a commonly used term for a specific test. This is usually the smallest unit of testing. A Test Case will consist of information such as requirements testing, test steps, verification steps, prerequisites, outputs, test environment, etc. A set of inputs, execution preconditions, and expected outcomes developed for a particular objective, such as to exercise a particular program path or to verify compliance with a specific requirement. Test Driven Development? Testing methodology associated with Agile Programming in which every chunk of code is covered by unit tests, which must all pass all the time, in an effort to eliminate unit-level and regression bugs during development. Practitioners of TDD write a lot of tests, i.e. an equal number of lines of test code to the size of the production code.
3. What is Test Driver?
A program or test tool used to execute a tests. Also known as a Test Harness.
4. What is Test Environment?
The hardware and software environment in which tests will be run, and any other software with which the software under test interacts when under test including stubs and test drivers.
5. What is Test First Design?
Test-first design is one of the mandatory practices of Extreme Programming (XP).It requires that programmers do not write any production code until they have first written a unit test.
6. What is Test Harness?
A program or test tool used to execute a tests. Also known as a Test Driver.
7. What is Test Plan?
A document describing the scope, approach, resources, and schedule of intended testing activities. It identifies test items, the features to be tested, the testing tasks, who will do each task, and any risks requiring contingency planning.
8. What is Test Procedure?
A document providing detailed instructions for the execution of one or more test cases.
9. What is Test Script?
Commonly used to refer to the instructions for a particular test that will be carried out by an automated test tool.
10. What is Test Specification?
A document specifying the test approach for a software feature or combination or features and the inputs, predicted results and execution conditions for the associated tests.
11. What is Test Suite?
A collection of tests used to validate the behavior of a product. The scope of a Test Suite varies from organization to organization. There may be several Test Suites for a particular product for example. In most cases however a Test Suite is a high level concept, grouping together hundreds or thousands of tests related by what they are intended to test.
12. What is Test Tools?
Computer programs used in the testing of a system, a component of the system, or its documentation.
13. What is Thread Testing?
A variation of top-down testing where the progressive integration of components follows the implementation of subsets of the requirements, as opposed to the integration of components by successively lower levels.
14. What is Top Down Testing?
An approach to integration testing where the component at the top of the component hierarchy is tested first, with lower level components being simulated by stubs. Tested components are then used to test lower level components. The process is repeated until the lowest level components have been tested.
15. What is Total Quality Management?
A company commitment to develop a process that achieves high quality product and customer satisfaction.
16. What is Traceability Matrix?
A document showing the relationship between Test Requirements and Test Cases.
17. What is Usability Testing?
Testing the ease with which users can learn and use a product.
18. What is Use Case?
The specification of tests that are conducted from the end-user perspective. Use cases tend to focus on operating software as an end-user would conduct their day-to-day activities.
19. What is Unit Testing?
Testing of individual software components.
20. What is Validation?
The process of evaluating software at the end of the software development process to ensure compliance with software requirements. The techniques for validation is testing, inspection and reviewing.
21. What is Verification?
The process of determining whether of not the products of a given phase of the software development cycle meet the implementation steps and can be traced to the incoming objectives established during the previous phase. The techniques for verification are testing, inspection and reviewing.
22. What is White Box Testing?
Testing based on an analysis of internal workings and structure of a piece of software. Includes techniques such as Branch Testing and Path Testing. Also known as Structural Testing and Glass Box Testing. Contrast with Black Box Testing. White box testing is used to test the internal logic of the code for ex checking whether the path has been executed once, checking whether the branches has been executed atleast once .....Used to check the structure of the code.
23. What is Workflow Testing?
Scripted end-to-end testing which duplicates specific workflows which are expected to be utilized by the end-user.
24. What's the difference between load and stress testing ?
One of the most common, but unfortunate misuse of terminology is treating “load testing” and “stress testing” as synonymous. The consequence of this ignorant semantic abuse is usually that the system is neither properly “load tested” nor subjected to a meaningful stress test. Stress testing is subjecting a system to an unreasonable load while denying it the resources (e.g., RAM, disc, mips, interrupts, etc.) needed to process that load. The idea is to stress a system to the breaking point in order to find bugs that will make that break potentially harmful. The system is not expected to process the overload without adequate resources, but to behave (e.g., fail) in a decent manner (e.g., not corrupting or losing data). Bugs and failure modes discovered under stress testing may or may not be repaired depending on the application, the failure mode, consequences, etc. The load (incoming transaction stream) in stress testing is often deliberately distorted so as to force the system into resource depletion. Load testing is subjecting a system to a statistically representative (usually) load. The two main reasons for using such loads is in support of software reliability testing and in performance testing. The term 'load testing' by itself is too vague and imprecise to warrant use. For example, do you mean representative load,' 'overload,' 'high load,' etc. In performance testing, load is varied from a minimum (zero) to the maximum level the system can sustain without running out of resources or having, transactions >suffer (application-specific) excessive delay. A third use of the term is as a test whose objective is to determine the maximum sustainable load the system can handle. In this usage, 'load testing' is merely testing at the highest transaction arrival rate in performance testing.
25. What's the difference between QA and testing?
QA is more a preventive thing, ensuring quality in the company and therefore the product rather than just testing the product for software bugs? TESTING means 'quality control' QUALITY CONTROL measures the quality of a product QUALITY ASSURANCE measures the quality of processes used to create a quality product.
26. What is the best tester to developer ratio?
Reported tester: developer ratios range from 10:1 to 1:10. There's no simple answer. It depends on so many things, Amount of reused code, number and type of interfaces, platform, quality goals, etc. It also can depend on the development model. The more specs, the less testers. The roles can play a big part also. Does QA own beta? Do you include process auditors or planning activities? These figures can all vary very widely depending on how you define 'tester' and 'developer'. In some organizations, a 'tester' is anyone who happens to be testing software at the time -- such as their own. In other organizations, a 'tester' is only a member of an independent test group. It is better to ask about the test labor content than it is to ask about the tester/developer ratio. The test labor content, across most applications is generally accepted as 50%, when people do honest accounting. For life-critical software, this can go up to 80%.
27. How can new Software QA processes be introduced in an existing organization?
- A lot depends on the size of the organization and the risks involved. For large organizations with high-risk (in terms of lives or property) projects, serious management buy-in is required and a formalized QA process is necessary. - Where the risk is lower, management and organizational buy-in and QA implementation may be a slower, step-at-a-time process. QA processes should be balanced with productivity so as to keep bureaucracy from getting out of hand. - For small groups or projects, a more ad-hoc process may be appropriate, depending on the type of customers and projects. A lot will depend on team leads or managers, feedback to developers, and ensuring adequate communications among customers, managers, developers, and testers. - In all cases the most value for effort will be in requirements management processes, with a goal of clear, complete, testable requirement specifications or expectations.
28. What are 5 common problems in the software development process?
1. poor requirements - if requirements are unclear, incomplete, too general, or not testable, there will be problems. 2. unrealistic schedule - if too much work is crammed in too little time, problems are inevitable. 3. inadequate testing - no one will know whether or not the program is any good until the customer complains or systems crash. 4. features - requests to pile on new features after development is underway; extremely common. 5. miscommunication - if developers don't know what's needed or customer's have erroneous expectations, problems are guaranteed.
29. What are 5 common solutions to software development problems?
1. solid requirements - clear, complete, detailed, cohesive, attainable, testable requirements that are agreed to by all players. Use prototypes to help nail down requirements. 2. 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. 3. adequate testing - start testing early on, re-test after fixes or changes, plan for adequate time for testing and bug-fixing. 4. stick to initial requirements as much as possible - be prepared to defend against changes and additions once development has begun, and be prepared to explain consequences. If changes are necessary, they should be adequately reflected in related schedule changes. If possible, use rapid prototyping during the design phase so that customers can see what to expect. This will provide them a higher comfort level with their requirements decisions and minimize changes later on. 5. communication - require walkthroughs and inspections when appropriate; make extensive use of group communication tools - e-mail, groupware, networked bug-tracking tools and change management tools, intranet capabilities, etc.; insure that documentation is available and up-to-date - preferably electronic, not paper; promote teamwork and cooperation; use prototypes early on so that customers' expectations are clarified.
30. 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 throughout 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 documentation of the overall program function and flow (even a few paragraphs is better than nothing); or if possible a separate flow chart and detailed program documentation. - make extensive use of error handling procedures and status and error logging. - for C++, to minimize complexity and increase maintainability, avoid too many levels of inheritance in class hierarchies (relative to the size and complexity of the application). Minimize use of multiple inheritance, and minimize use of operator overloading (note that the Java programming language eliminates multiple inheritance and operator overloading.) - for C++, keep class methods small, less than 50 lines of code per method is preferable. - for C++, make liberal use of exception handlers
31. 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.
32. What makes a good test engineer?
A good test engineer has a 'test to break' attitude, an ability to take the point of view of the customer, a strong desire for quality, and an attention to detail. Tact and diplomacy are useful in maintaining a cooperative relationship with developers, and an ability to communicate with both technical (developers) and non-technical (customers, management) people is useful. Previous software development experience can be helpful as it provides a deeper understanding of the software development process, gives the tester an appreciation for the developers' point of view, and reduce the learning curve in automated test tool programming. Judgment skills are needed to assess high-risk areas of an application on which to focus testing efforts when time is limited.
33. 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.
34. 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
35. What's the role of documentation in QA?
Critical. (Note that documentation can be electronic, not necessarily paper.) QA practices should be documented such that they are repeatable. Specifications, designs, business rules, inspection reports, configurations, code changes, test plans, test cases, bug reports, user manuals, etc. should all be documented. There should ideally be a system for easily finding and obtaining documents and determining what documentation will have a particular piece of information. Change management for documentation should be used if possible.
36. What's the big deal about 'requirements'?
One of the most reliable methods of insuring problems, or failure, in a complex software project is to have poorly documented requirements specifications. Requirements are the details describing an application's externally-perceived functionality and properties. Requirements should be clear, complete, reasonably detailed, cohesive, attainable, and testable. A non-testable requirement would be, for example, 'user-friendly' (too subjective). A testable requirement would be something like 'the user must enter their previously-assigned password to access the application'. Determining and organizing requirements details in a useful and efficient way can be a difficult effort; different methods are available depending on the particular project. Many books are available that describe various approaches to this task. Care should be taken to involve ALL of a project's significant 'customers' in the requirements process. 'Customers' could be in-house personnel or out, and could include end-users, customer acceptance testers, customer contract officers, customer management, future software maintenance engineers, salespeople, etc. Anyone who could later derail the project if their expectations aren't met should be included if possible. Organizations vary considerably in their handling of requirements specifications. Ideally, the requirements are spelled out in a document with statements such as 'The product shall.....'. 'Design' specifications should not be confused with 'requirements'; design specifications should be traceable back to the requirements. In some organizations requirements may end up in high level project plans, functional specification documents, in design documents, or in other documents at various levels of detail. No matter what they are called, some type of documentation with detailed requirements will be needed by testers in order to properly plan and execute tests. Without such documentation, there will be no clear-cut way to determine if a software application is performing correctly.
37. 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.) - 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
38. What is 'configuration management'?
Configuration management covers the processes used to control, coordinate, and track: code, requirements, documentation, problems, change requests, designs, tools/compilers/libraries/patches, changes made to them, and who makes the changes.
39. 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.
40. 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
41. 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?
42. What can be done if requirements are changing continuously?
A common problem and a major headache. - Work with the project's stakeholders early on to understand how requirements might change so that alternate test plans and strategies can be worked out in advance, if possible. - It's helpful if the application's initial design allows for some adaptability so that later changes do not require redoing the application from scratch. - If the code is well-commented and well-documented this makes changes easier for the developers.- Use rapid prototyping whenever possible to help customers feel sure of their requirements and minimize changes. - The project's initial schedule should allow for some extra time commensurate with the possibility of changes.- Try to move new requirements to a 'Phase 2' version of an application, while using the original requirements for the 'Phase 1' 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 re-do 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).
43. 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.
44. What if the application has functionality that wasn't in the requirements?
It may take serious effort to determine if an application has significant unexpected or hidden functionality, and it would indicate deeper problems in the software development process. If the functionality isn't necessary to the purpose of the application, it should be removed, as it may have unknown impacts or dependencies that were not taken into account by the designer or the customer. If not removed, design information will be needed to determine added testing needs or regression testing needs. Management should be made aware of any significant added risks as a result of the unexpected functionality. If the functionality only effects areas such as minor improvements in the user interface, for example, it may not be a significant risk.
45. How can Software QA processes be implemented without stifling productivity?
By implementing QA processes slowly over time, using consensus to reach agreement on processes, and adjusting and experimenting as an organization grows and matures, productivity will be improved instead of stifled. Problem prevention will lessen the need for problem detection, panics and burn-out will decrease, and there will be improved focus and less wasted effort. At the same time, attempts should be made to keep processes simple and efficient, minimize paperwork, promote computer-based processes and automated tracking and reporting, minimize time required in meetings, and promote training as part of the QA process. However, no one - especially talented technical types - likes rules or bureaucracy, and in the short run things may slow down a bit. A typical scenario would be that more days of planning and development will be needed, but less time will be required for late-night bug-fixing and calming of irate customers.
46. What if an organization is growing so fast that fixed QA processes are impossible?
This is a common problem in the software industry, especially in new technology areas. There is no easy solution in this situation, other than: - Hire good people - Management should 'ruthlessly prioritize' quality issues and maintain focus on the customer - Everyone in the organization should be clear on what 'quality' means to the customer
47. 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. 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.
48.How can World Wide Web sites be tested?
Web sites are essentially client/server applications - with web servers and 'browser' clients. Consideration should be given to the interactions between html pages, TCP/IP communications, Internet connections, firewalls, applications that run in web pages (such as applets, javascript, plug-in applications), and applications that run on the server side (such as cgi scripts, database interfaces, logging applications, dynamic page generators, asp, etc.). Additionally, there are a wide variety of servers and browsers, various versions of each, small but sometimes significant differences between them, variations in connection speeds, rapidly changing technologies, and multiple standards and protocols. The end result is that testing for web sites can become a major ongoing effort. Other considerations might include: - What are the expected loads on the server (e.g., number of hits per unit time?), and what kind of performance is required under such loads (such as web server response time, database query response times). What kinds of tools will be needed for performance testing (such as web load testing tools, other tools already in house that can be adapted, web robot downloading tools, etc.)? - Who is the target audience? What kind of browsers will they be using? What kind of connection speeds will they by using? Are they intra- organization (thus with likely high connection speeds and similar browsers) or Internet-wide (thus with a wide variety of connection speeds and browser types)? - What kind of performance is expected on the client side (e.g., how fast should pages appear, how fast should animations, applets, etc. load and run)? - Will down time for server and content maintenance/upgrades be allowed? how much? - What kinds of security (firewalls, encryptions, passwords, etc.) will be required and what is it expected to do? How can it be tested? - How reliable are the site's Internet connections required to be? And how does that affect backup system or redundant connection requirements and testing? - What processes will be required to manage updates to the web site's content, and what are the requirements for maintaining, tracking, and controlling page content, graphics, links, etc.? - Which HTML specification will be adhered to? How strictly? What variations will be allowed for targeted browsers? - Will there be any standards or requirements for page appearance and/or graphics throughout a site or parts of a site?? - How will internal and external links be validated and updated? how often? - Can testing be done on the production system, or will a separate test system be required? How are browser caching, variations in browser option settings, dial-up connection variabilities, and real-world internet 'traffic congestion' problems to be accounted for in testing?- How extensive or customized are the server logging and reporting requirements; are they considered an integral part of the system and do they require testing?- How are cgi programs, applets, javascripts, ActiveX components, etc. to be maintained, tracked, controlled, and tested? - Pages should be 3-5 screens max unless content is tightly focused on a single topic. If larger, provide internal links within the page. - The page layouts and design elements should be consistent throughout a site, so that it's clear to the user that they're still within a site. - Pages should be as browser-independent as possible, or pages should be provided or generated based on the browser-type. - All pages should have links external to the page; there should be no dead-end pages. - The page owner, revision date, and a link to a contact person or organization should be included on each page.
49. How is testing affected by object-oriented designs?
Well-engineered object-oriented design can make it easier to trace from code to internal design to functional design to requirements. While there will be little affect on black box testing (where an understanding of the internal design of the application is unnecessary), white-box testing can be oriented to the application's objects. If the application was well-designed this can simplify test design.
50. What is Extreme Programming and what's it got to do with testing?
Extreme Programming (XP) is a software development approach for small teams on risk-prone projects with unstable requirements. It was created by Kent Beck who described the approach in his book 'Extreme Programming Explained'. Testing ('extreme testing') is a core aspect of Extreme Programming. Programmers are expected to write unit and functional test code first - before the application is developed. Test code is under source control along with the rest of the code. Customers are expected to be an integral part of the project team and to help develop scenarios for acceptance/black box testing. Acceptance tests are preferably automated, and are modified and rerun for each of the frequent development iterations. QA and test personnel are also required to be an integral part of the project team. Detailed requirements documentation is not used, and frequent re-scheduling, re-estimating, and re-prioritizing is expected.
