1Testing Course

explaining the

ISTQB Certified Tester Foundation Level Syllabus

2(the common answer is :) To find bugs!...but consider also:

To reduce the impact of the failures at the clients site (live defects) and ensure that they will not affect costs & profitability

To decrease the rate of failures (increase the products reliability)To improve the quality of the productTo ensure requirements are implemented fully & correctlyTo validate that the product is fit for its intended purpose To verify that required standards and legal requirements are metTo maintain the company reputation

Testing provides the products measure of quality!

Can we test everything? Exhaustive testing is possible?

-No, sorry time & resources make it impractical !but, instead:-We must understand the risk to the clients business of the software not functioning correctly

We must manage and reduce risk, carry out a Risk Analysis of the application

Prioritise tests to focus them (time & resources) on the main areas of risk

1.1.1 Why is testing necessary Why do we test?

3The main goals of testing:

Find defects Assess the level of quality of the software product and providing related information to the stakeholders

Prevent defects Reduce risk of operational incidents Increase the product quality

Different viewpoints and objectives:

Unit & integration test find as many defects as possible Acceptance testing confirm that the system works as specified and that the quality is good enough

Testing metrics gathering provide information to the project manager about the product quality and the risks involved

Design tests early and review requirements help prevent defects

1.1.1 Why is testing necessary - Testing goals and objectives

4A programmer (or analyst) can make an error (mistake), which produces a defect

(fault, bug) in the programs code. If such a defect in the code is executed, the system will fail to do what it should do (or it will do something it should not do),

causing a failure.

Error (mistake) = a human action that produces an incorrect result

Defect (bug) = a flaw that can cause the component or system to fail to perform its

required function

Failure = deviation of the component or system from its expected delivery, service

or result

Anomaly = any condition that deviates from expectations based on requirements

specifications, design documents, user documentation, standards or someones perceptions or expectations

Defect masking = An occurrence in which one defect prevents the detection of

another.

1.1.2 Why is testing necessary - Testing Glossary

5Defects are caused by human errors!

Why? Because of:

Time pressure - the more pressure we are under the more likely we are to

make mistakes

Code complexity or new technologyToo many system interactionsRequirements not clearly defined, changed & not properly documentedWe make wrong assumptions about missing bits of information!Poor communicationPoor training

1.1.2 Why is testing necessary Causes of the errors

6(Boris Beizer)

Requirements (incorrect, logic, completeness, verifiability, documentation, changes) Features and functionality (correctness, missing case, domain and boundary,

messages, exception mishandled)

Structural (control flow, sequence, data processing) Data (definition, structure, access, handling) Implementation and Coding Integration (internal and external interfaces) System (architecture, performance, recovery, partitioning, environment) Test definition and execution (test design, test execution, documentation, reporting)

(Cem Kaner (b1))

User interface (functionality, communication, missing, performance, output) Error handling (prevention, detection, recovery) Boundary (numeric, loops) Calculation (wrong constants, wrong operation order, over & underflow) Initialization (data item, string, loop control) Control flow (stop, crash, loop, if-then-else,) Data handling (data type, parameter list, values) Race & Load conditions (event sequence, no resources) Source and version control (old bug reappear) Testing (fail to notice, fail to test, fail to report)

1.1.2 Why is testing necessary - Causes of software defects -

Defects taxonomy

7Testers do cooperate with:

Analysts to review the specifications for completeness and correctness, ensure that they are testable

Designers to improve interfaces testability and usability Programmers to review the code and assess structural flaws Project manager to estimate, plan, develop test cases, perform tests and report bugs, to assess the quality and risks

Quality assurance staff to provide defect metrics Interactions with these project roles are very complex.

1.1.3 Why is testing necessary - The role of testing in the

software life cycle

RACI matrix (Responsible, Accountable, Consulted, Informed)

81.1.4 Why is testing necessary What is quality?

Quality (ISO) = The totality of the characteristics of an entity that bear on its

ability to satisfy stated or implied needs

there are many more definitions

Testing means not only to Verify (the thing is done right)

but also to Validate (the right thing is done)!

Software quality includes: reliability, usability, efficiency, maintainability and

portability.

RELIABILITY: The ability of the software product to perform its required

functions under stated conditions for a specified period of time, or for a

specified number of operations.

USABILITY: The capability of the software to be understood, learned, used and

attractive to the user when used under specified conditions.

EFFICIENCY: The capability of the software product to provide appropriate

performance, relative to the amount of resources used under stated conditions.

MAINTAINABILITY: The ease with which a software product can be modified

to correct defects, modified to meet new requirements, modified to make future

maintenance easier, or adapted to a changed environment.

PORTABILITY:The ease with which the software product can be transferred

from one hardware or software environment to another.

9Testing does not inject Quality into

the product, but will measure the

level of the Quality of the product.

Quality can be measured for:

progress variance (planned versus actual)

1.1.4 Why is testing necessary - Testing and quality

Measuring product quality:

Functional compliance - functional software requirements testingNon functional requirementsTest coverage criteriaDefect count or defect trend criteria

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1.1.4 Why is testing necessary quality attributes

The QUINT model (extended ISO model)

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The five basic criteria often used to decide when to stop testing are:

Previously defined coverage goals have been met The defect discovery rate has dropped below a previously defined threshold The cost of finding the "next" defect exceeds the expected loss from that defect The project team reaches consensus that it is appropriate to release the product The manager decides to deliver the product

All these criteria are risk based.

It is important not depending on only one stopping criterion.

Software Reliability Engineering can help also to determine when to stop testing,

by taking into consideration aspects like failure intensity.

1.1.5 Why is testing necessary - How much testing is enough?

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Testing = the process concerned with planning the necessary static and dynamic

activities, preparation and evaluation of software products and related deliverables,

in order to:

determine that they satisfy specified requirements demonstrate that they are fit for the intended use detect defects, help and motivate the developers to fix them measure, assess and improve the quality of the software product

Testing should be performed throughout the whole software life cycle

There are two basic types of testing: execution and non-execution based

Other definitions:

(IEEE) Testing = the process of analyzing a software item to detect the differences between existing and required conditions and to evaluate its features

(Myers (b3)) Testing = the process of executing a program with the intent of finding errors

(Craig & Jaskiel (b5)) Testing = a concurrent lifecycle process of engineering, using and maintaining test-ware in order to measure and improve the quality of the

software being tested

1.2 What is testing - Definition of testing

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Analytic School - testing is rigorous, academic and technicalTesting is a branch of CS/MathematicsTesting techniques must have a logic-mathematical formKey Question: Which techniques should we use?Require precise and detailed specifications

Factory School - testing is a way to measure progress, with emphasis on cost and

repeatable standardsTesting must be managed & cost effectiveTesting validates the product & measures development progressKey Questions: How can we measure whether were making progress, When will we be done?Require clear boundaries between testing and other activities (start/stop criteria)Encourage standards (V-model), best practices, and certification

Quality School - emphasizes process & quality, acting as the gatekeeperSoftware quality requires disciplineTesters may need to police developers to follow the rulesKey Question: Are we following a good process?Testing is a stepping stone to process improvement

Context-Driven School - emphasizes people, setting out to find the bugs that will be

most important to stakeholdersSoftware is created by people. People set the contextTesting finds bugs acting as a skilled, mental activityKey Question: What testing would be most valuable right now?Expect changes. Adapt testing plans based on test resultsTesting research requires empirical and psychological study

1.2 What is testing Testing schools

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Testing shows presence of defects, but cannot prove that there are no more defects; testing can only reduce the probability of undiscovered defects

Complete, exhaustive testing is impossible; good strategy and risk management must be used

Pareto rule (defect clustering): usually 20% of the modules contain 80% of the bugs

Early testing: testing activities should start as soon as possible (including here planning, design, reviews)

Pesticide paradox: if the same set of tests are repeated over again, no new bugs will be found; the test cases should be reviewed, modified and new test cases

developed

Context dependence: test design and execution is context dependent (desktop, web applications, real-time, )

Verification and Validation: discovering defects cannot help a product that is not fit to the users needs

1.3 General testing principles

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Operability - The better it works, the more efficiently it can be tested

Observability - What we see is what we test

Controllability - The better we control the software, the more the testing process

can be automated and optimized

Decomposability - By controlling the scope of testing, we can quickly isolate

problems and perform effective and efficient testing

Simplicity - The less there is to test, the more quickly we can test it

Stability - The fewer the changes, the fewer are the disruptions to testing

Understandability - The more information we will have, the smarter we will test

Suitability - The more we know about the intended use of the software, the

better we can organize our testing to find important bugs

1.3 General testing principles heuristics of software testing

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-Test Planning & Test control

-Test Analysis & Design

-Test Implementation &

Execution

-Evaluating exit criteria &

Reporting

-Test Closure activities

1.4.1 Fundamental test process phases

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Planning

1. Determine scope

Study project documents, used software life-cycle specifications, product desired quality attributes

Clarify test process expectations2. Determine risks

Choose quality risk analysis method (e.g. FMEA) Document the list of risks, probability, impact, priority, identify mitigation actions

3. Estimate testing effort, determine costs, develop schedule

Define necessary roles Decompose test project into phases and tasks (WBS) Schedule tasks, assign resources, set-up dependencies

4. Refine plan

Select test strategy (how to do it, what test types at which test levels) Select metrics to be used for defect tracking, coverage, monitoring Define entry and exit criteria

Control

Measure and analyze results Monitor testing progress, coverage, exit criteria Assign or reallocate resources, update the test plan schedule Initiate corrective actions

Make decisions

1.4.1 Fundamental test process planning & control

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Reviewing the test basis (such as requirements, architecture, design, interfaces).

Identifying test conditions or test requirements and required test data based on analysis of test items and the specification.

Designing the tests: Choose test techniques Identify test scenarios, pre-conditions, expected results, post-

conditions

Identify possible test Oracles Evaluating testability of the requirements and system. Designing the test environment set-up and identifying any required

infrastructure and tools.

(see Lee Copeland (b2))

1.4.2 Fundamental test process analysis & design

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The expected result (test outcome) must be defined at the test analysis stage Who will decide that (expected result = actual result), when the test will be

executed? The Test Oracle!

Test Oracle = A source to determine expected result, a principle or mechanism to

recognize a problem. The Test Oracle can be:

an existing system (the old version) a document (specification, user manual) a competent client representative but never the source code itself !

Oracles in use = Simplification of Risk : do not assess pass - fail, but instead problem - no problem

Problem: Oracles and Automation - Our ability to automate testing is

fundamentally constrained by our ability to create and use oracles;

Possible issues:

false alarms missed bugs

1.4.2 Fundamental test process what is a test Oracle?

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1.4.3 Fundamental test process implementation & execution

Test implementation:

Develop and prioritize test cases, create test data, test harnesses and automation scripts Create test suites from the test cases Check test environmentTest execution:

Execute (manually or automatically) the test cases (suites) Use Test Oracles to determine if test passed or failed Login the outcome of tests execution Report incidents (bugs) and try to discover if they are caused by the test data, test procedure or they are defect failures

Expand test activities as necessary, according to the testing mission(see Rex Black (b4))

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1.4.3 Fundamental test process prioritizing the Test Cases

Why prioritize the Test Cases?

It is not possible to test everything, we must do our best in the time available

Testing must be Risk based, assuring that the errors, that will get through to the clients production system, will have the smallest possible impact and frequency of occurrence

This means we must prioritise and focus testing on the priorities

What to watch?

Severity of possible defectsProbability of possible defectsVisibility of possible defectsClient Requirement importanceBusiness or technical criticality of a featureFrequency of changes applied to a moduleScenarios complexity

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1.4.4 Fundamental test process evaluating exit criteria and reporting

Evaluate exit criteria:

Check test logs against exit criteria specified in test mission definition Assess if more tests are needed Check if testing mission should be changed

Test reporting:

Write the test summary report for the stakeholders use

The test summary report should include:

Test Cases execution coverage (% executed ) Test Cases Pass / Fail % Active bugs, sorted according to their severity

(see Rex Black (b4) & RUP- Test discipline(s5))

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1.4.5 Fundamental test process test closure

Verify if test deliverables have been delivered

Check and close the remaining active bug reports

Archiving the test-ware and environment

Handover of the test environment

Analyze the identified test process problems (lessons learned)

Implement action plan based improvements

(see Rex Black (b4))

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1.5 The psychology of testing

Testing is regarded as a destructive activity (we run tests to make the software fail)

A good tester:

Should always have a critical approachMust keep attention to detailMust have analytical skillsShould have good verbal and written communication skills

Must analyse incomplete factsMust work with incomplete factsMust learn quickly about the product being tested

Should be able to quickly prioritiseShould be a planned, organised kind of person

Also, he must have a good knowledge about:

The customers business workflowsThe product architecture and interfacesThe software project processTesting techniques and practices

Rex Blacks Top 10 professional errors

Fall in Love with a Tool Write Bad Bug Reports Fail to Define the Mission Ignore a Key Stakeholder Deliver Bad News Badly Take Sole Responsibility for Quality Be an Un-appointed Process Cop Fail to Fire Someone who Needs Firing Forget Youre Providing a Service Ignore Bad Expectations

(see also Brian Maricks article)

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1.5 The psychology of testing

The best tester isnt the one who finds the most bugs, the best tester is the one who gets the most bugs fixed (Cem Kaner)

Selling bugs (see Cem Kaner (c1) Motivate the programmer

Demonstrate the bug effects Overcome objections Increase the defect description coverage (indicate detailed preconditions, behavior) Analyze the failure Produce a clear, short, unambiguous bug report Advocate error costs

Levels of Independence of the Testing Team:

Low Developers write and execute their own testsMedium Tests are written and executed by another developerHigh Tests written and executed by an independent testing team (internal or external)

Testers Agile Manifesto (Jonathan Kohl)

bug advocacy over bug counts testable software over exhaustive (requirements) docs measuring product success over measuring process success team collaboration over departmental independence

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2.1.1 The V testing model

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2.1.1 The V testing model Verification & ValidationVerification = Confirmation by

examination and through the

provision of objective evidence that

specified requirements have been

fulfilled.

Validation = Confirmation by

examination and through provision of

objective evidence that the

requirements for a specific intended

use or application have been fulfilled.

Verification is the dominant activity in

the Unit, Integration, System testing

levels, Validation is a mandatory

activity in the Acceptance testing level

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2.1.1 The W testing model dynamic testing

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2.1.1 The W testing model static testing

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2.1.2 Software development models - Waterfall

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2.1.2 Software development models - Waterfall

Waterfall weaknesses

Linear: any attempt to go back two or more phases to correct a problem or

deficiency results in major increases in cost and schedule

Integration problems usually surface too late. Previously undetected errors

or design deficiencies will emerge, adding risk with little time to recover

Users can't see quality until the end. They can't appreciate quality if the

finished product can't be seen

Deliverables are created for each phase and are considered frozen. If the

deliverable of a phase changes, which often happens, the project will suffer

schedule problems

The entire software product is being worked on at one time. There is no way to

partition the system for delivery of pieces of the system

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2.1.2 Software development models - Rapid Prototype Model

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2.1.2 Software development models - Rapid Prototype Model

Rapid Prototype Model weaknesses

In the rush to create a working prototype, overall software quality or

long-term maintainability may be overlooked

Tendency for difficult problems to be pushed to the future, causing the

initial promise of the prototype to not be met by subsequent products

Developers may fall into a code-and-fix cycle, leading to expensive,

unplanned prototype iterations

Customers become frustrated without the knowledge of the exact

number of iterations that will be necessary

Users may have a tendency to add to the list of items to be prototyped

until the scope of the project far exceeds the feasibility study

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2.1.2 Software development models - Incremental Model

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2.1.2 Software development models - Incremental Model

Incremental Model weaknesses

Definition of a complete, fully functional system must be done early in

the life cycle to allow for the definition of the increments

The model does not allow for iterations within each increment

Because some modules will be completed long before others, well-

defined interfaces are required

Requires good planning and design: Management must take care to

distribute the work; the technical staff must watch dependencies

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2.1.2 Software development models - Spiral Model

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2.1.2 Software development models - Spiral Model

Spiral Model weaknesses

The model is complex, and developers, managers, and customers may find it

too complicated to use

Considerable risk assessment expertise is required

Hard to define objective, verifiable milestones that indicate readiness to

proceed through the next iteration

May be expensive - time spent planning, resetting objectives, doing risk

analysis, and prototyping may be excessive

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2.1.2 Software development models - Rational Unified Process

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2.1.3 Software development models Testing life cycle

For each software activity, there must be a corresponding testing activity

The objectives of the testing are specific to that tested activity

Plan, analysis and design of a testing activity should be done during the corresponding development activity

Review and inspection must be considered as part of testing activities

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2.2.1 Test levels Component testing

Target: single software modules, components that are separately testable

Access to the code being tested is mandatory, usually involves the programmer

May consist of:

o Functional tests

o Non-functional tests (stress test)

o Structural tests (statement coverage, branch coverage)

Test cases follow the low level specification of the module

Can be automated (test driven software development):

o Develop first test code

o Then, write the code to be tested

o Execute until pass

Also named Unit testing

Good programming style (Design-by-contract, respecting Demeters law) enhance the efficiency of Unit testing

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2.2.2 Test levels Integration testing

Target: the interfaces between components and interfaces with other parts of

the system

We focus on the data exchanged, not on the tested functionalities.

Product software architecture understanding is critical

May consist of:

o Functional tests

o Non-functional tests (ex: performance test)

o Component integration testing (after component testing)

o System integration testing (after system testing)

Test strategy may be bottom-up, top-down or big-bang

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2.2.2 Test levels Component Integration testing

Component integration testing (done after Component testing) :

Linking a few components to check that they communicate correctly

Iteratively linking more components together

Verify that data is exchanged between the components as required

Increase the number of components, create & test subsystems and finally the complete system

Drivers and Stubs should be used when necessary:

driver: A software component or test tool that replaces a component that takes care of the control and/or the calling of a component or system.

stub: A skeletal or special-purpose implementation of a software component, used to develop or test a component that calls or is otherwise dependent on it. It replaces

a called component.

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2.2.2 Test levels System Integration testing

System integration testing (done after System or Acceptance testing) :

Testing the integration of systems and packages; testing interfaces to external

organizations

We check the data exchanged between our system and other external systems.

Additional difficulties:

Multiple PlatformsCommunications between platformsManagement of the environments

Approaches to access the external systems:

Testing in a test environmentTesting in a clone of a production environmentTesting in a real production environment

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2.2.3 Test levels System testing

System testing = The process of testing an integrated system to verify that it meets

specified requirements

Target: the whole product (system) as defined in the scope document

Environment issues are critical

May consist of:

o Functional tests, based on the requirement specifications

o Non-functional tests (ex: load tests)

o Structural tests (ex: web page links, or menu item coverage)

Black box testing techniques may be used (ex: business rule decision table)

Test strategy may be risk based

Test coverage is monitored

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2.2.4 Test levels Acceptance testing

Acceptance Testing = Formal testing with respect to user needs, requirements,

and business processes conducted to determine whether or not a system satisfies

the acceptance criteria and to enable the user, customers or other authorized entity

to determine whether or not to accept the system

The main goals:

establish confidence in the systemis the product good enough to be delivered to the client?

The main focus is not to find defects, but to assess the readiness for deployment

It is not necessary the final testing level; a final system integration testing session can be executed after the acceptance tests

May be executed also after component testing (component usability acceptance)Usually involves client representatives

Typical forms:User acceptance: business aware users verify the main featuresOperational acceptance testing: backup-restore, security, maintenanceAlpha and Beta testing: performed by customers or potential users

Alpha : at the developers siteBeta : at the customers site

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2.3.1 Test types Functional testing

Target: Test the functionalities (features) of a product

Specification based:

uses Test Cases, derived from the specifications (Use Cases)

business process based, using business scenarios

Focused on checking the system against the specifications

Can be performed at all test levels

Considers the external behavior of the system

Black box design techniques will be used

Security testing is part of functional testing, related to the detection of threats

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2.3.2 Test types Non-Functional testing

Non functional testing = testing the attributes of a component or system that do

not relate to functionality, e.g. reliability, efficiency, usability, maintainability and

portability

Targeted to test the product quality attributes:

Performance testing

Load testing (how much load can be handled by the system?)

Stress testing (evaluate system behavior at limits and out of limits)

Usability testing

Reliability testing

Portability testing

Maintainability testing

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2.3.2 Test types Non-Functional testing - Usability

Usability testing = used to determine the extent to

which the software product is understood, easy to

learn, easy to operate and attractive to the users

under specified conditions

People selected from the potential users may be involved to study how they use the system

A quick and focused beta-test may be a cheap way of doing Usability testing

There is no simple way to examine how people will use the system

Easy to understood is not the same as easy to learn or as easy to use or as easy to operate

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2.3.2 Test types Non-Functional testing - Instalability

Instalability testing = The process of testing the installability of a software

product

Does the installation work?

How easy is to install the system?

Does installation affect other software?

Does the environment affect the product?

Does it uninstall correctly?

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2.3.2 Test types Non-Functional testing Load, Stress, Performance, Volume testing

Load Test = A test type concerned with measuring the behavior of a component

or system with increasing load, e.g. number of parallel users and/or numbers of

transactions to determine what load can be handled by the component or system

Stress Test = Testing conducted to evaluate a system or component at or

beyond the limits of its specified requirements.

Performance Test = The process of testing to determine the performance of a

software product. Performance can be measured watching:

Response timeThroughputResources utilization

Spike Test = Keeping the system, periodically, for short amounts of time, beyond

its specified limits

Endurance Test = a Load Test performed for a long time interval (week(s))

Volume Test = Testing where the system is subjected to large volumes of data

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2.3.3 Test types Structural testing

Targeted to test:

o internal structure (component)

o architecture (system)

Uses only white box design techniques

Can be performed at all test levels

Used also to help measure the coverage (% of items being covered by tests)

Tool support is critical

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2.3.4 Test types Confirmation & regression testing

Confirmation testing = Re-testing of a module or product, to confirm that the

previously detected defect was fixed

Implies the use of a bug tracking tool

Confirmation testing is not the same as the debugging (debugging is a development activity, not a testing activity)

Regression testing = Re-testing of a previously tested program following

modification to ensure that defects have not been introduced or uncovered as a

result of the changes made. It is performed when the software or its environment

is changed

Can be performed at all test levels

Can be automated (because of cost and schedule reasons)

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2.4 Maintenance testing

Maintenance testing = Testing the changes to an operational system or the

impact of a changed environment to an operational system

Done on an existing operational system, triggered by modification, retirement or

migration of the software

Include:

Release based changesCorrective changesDatabase upgrades

Regression testing is also involved

Impact analysis = determining how the existing system may be affected by

changes (used to help decide how much regression testing to do)

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3.1 Reviews and the testing process

Static Testing = testing of a component or system at specification or

implementation level without execution of that software, e.g. reviews (manual) or

static code analysis (automated)

Reviews

Why review?

To identify errors as soon as possible in the development lifecycleReviews offer the chance to find omissions and errors in the software specifications

The target of a review is a software deliverable:

Specification

Use case

Design

Code

Test case

Manual

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3.1 Reviews and the testing process

When to review?

As soon as an software artifact is produced, before it is used as the basis for the next step in development

Benefits include:

Early defect detection

Reduced testing costs and time

Can find omissions

Risks:

If misused they can lead to project team members frictionsThe errors & omissions found should be regarded as a positive issueThe author should not take the errors & omissions personallyNo follow up to is made to ensure correction has been madeWitch-hunts used when things are going wrong

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3.2.1 Phases of a formal review

Formal review phases:

Planning: define scope, select participants, allocate roles, define entry & exit criteria

Kick-off: distribute documents, explain objectives, process, check entry criteria

Individual preparation: each of participants studies the documents, takes notes, issues questions and comments

Review meeting: meeting participants discuss and log defects, make recommendations

Rework: fixing defects (by the author)Follow-up: verify again, gather metrics, check exit criteria

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3.2.2 Roles in a formal review

The formal reviews can use the following predefined roles:

Manager: schedules the review, monitor entry and exit criteria

Moderator: distributes the documents, leads the discussion, mediates

various conflicting opinions

Author: owner of the deliverable to be reviewed

Reviewer: technical domain experts, identify and note findings

Scribe: records and documents the discussions during the meeting

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3.2.3 Types of review

Informal review

A peer or team lead reviews a software deliverable

Without applying a formal processDocumentation of the review is optionalQuick way of finding omissions and defectsAmplitude and depth of the review depends on the reviewer

Main purpose: inexpensive way to get some benefit

Walkthrough

The author of the deliverable leads the review activity, others participate

Preparation of the reviewers is optionalScenario basedThe sessions are open-endedCan be informal but also formalMain purposes: learning, gaining understanding, defect finding

Technical Review

Formal Defect detection processMain meeting is preparedTeam includes peers and technical domain experts

May vary in practice from quite informal to very formal

Led by a moderator, which is not the authorChecklists may be used, reports can be preparedMain purposes: discuss, make decisions, evaluate alternatives, find defects, solve technical

problems and check conformance to

specifications and standards.

Inspection

Formal process, based on checklists, entry and

exit criteria

Dedicated, precise roles

Led by the moderator

Metrics may be used in the assessment

Reports, list-of-findings are mandatory

Follow-up process

Main purpose: find defects

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3.2.4 Success factors for reviews

Clear objective is set

Appropriate experts are involved

Identify issues, not fix them on-the-spot

Adequate psychological handling (author is not punished for the found

defects)

Level of formalism is adapted to the concrete situation

Minimal preparation and training

Management encourages learning, process improvement

Time-boxing is used to determine time allocated to each part of the

document to be reviewed

Use of effective and specialized checklists ( requirements, test cases )

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3.3 Static analysis by tools

Performed without executing the examined software, but assisted by tools

The approach may be data flow or control flow based

Benefits:

early defects detection

early warnings about unwanted code complexity

detects missing links

improved maintainability of code and design

Typical defects discovered:

reference to an un-initialized variable

never used variables

unreachable code

programming standards violations

security vulnerabilities

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4. Test design techniques - glossary

Test condition = item, event, attribute of a module or system that could

be verified (ex: feature, structure element, transaction, quality attribute)

Test data = data that affects or is affected by the execution of the

specific module

Test case [IEEE] = a set of input values, execution preconditions,

expected results and execution post-conditions, developed for a particular

objective or test condition, such as to exercise a particular program path or

to verify compliance with a specific requirement

Test case specification [IEEE] = a document specifying a set of test

cases for a test condition

Test procedure (suite) specification = a document specifying a

sequence of actions for the execution of a series of test cases

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4.1 Test design test development process

1. Identify test conditions:

Inputs:

Field levelGroup level

Capability related:

Trigger conditionsConstraints or limitsInterfaces to other productsValidation of inputs at the following levels of aggregation:

Field / action / messageRecord / row / windowFile / table / screenDatabase

Product statesBehavior rules

Architectural design related:

Invocation pathsCommunication pathsInternal data conditionsDesign statesExceptions

2. Develop test cases

Use cases are used as input

Test cases will cover all possible paths of the

execution graph flow

Test data should be specified if necessary

Priorities of Test cases should be assigned

Traceability matrix (Use cases x Test cases)

should be maintained

3. Develop test procedures

Group test cases into execution schedules

Factors to be considered:

a. Prioritization

b. Logical dependencies

c. Regression tests

Traceability from test condition to the

specifications (requirements) is a must

Risk analysis is a best practice

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4.2 Test design categories of test design techniques

Black box: no internal structure knowledge will be used

White box: based on the analysis of the internal structure

Static: without running, exercised on specific project artifacts

Each black box or white box test technique has:

A method (how to do it)A test case design approach (how to create test cases using the approach)A measurement technique coverage % (except the black box Syntax testing)

Other taxonomy:

Specification based: test cases are built from the specifications of the module

Structure based: information about the module is constructed (design, code) is

used to derive the test cases

Experience based: testers knowledge about the specific domain, about the likely defects, is used

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4.3.1 Black box techniques equivalence partitioning

To minimize testing, partition input (output) values into groups of equivalent

values (equivalent from the test outcome perspective)

Select a value from each equivalence class as a representative value

If an input is a continuous range of values, then there is typically one class of valid

values and two classes of invalid values, one below the valid class and one

above it.

Example: Rule for hiring a person is second its age:

0 15 = do not hire

16 17 = part time

18 54 = full time

55 -- 99 = do not hire

Which are the valid equivalence classes? And the invalid ones?

Give examples of representative values!

(other examples)

(see Lee Copeland b2 chap.3, Cem Kaner c1, Paul Jorgensen b7 chap.2.2,6.3)

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4.3.1 Black box techniques all-pairs testing

In practice, there are situations when a great number of combinations must be

tested. For example: A Web site must operate correctly with different browsersInternet Explorer 5.0, 5.5, and 6.0, Netscape 6.0, 6.1, and 7.0, Mozilla 1.1, and

Opera 7; using different plug-insRealPlayer, MediaPlayer, or none; running on different client operating systemsWindows 95, 98, ME, NT, 2000, and XP; receiving pages from different serversIIS, Apache, and WebLogic; running on different server operating systemsWindows NT, 2000, and Linux.

Test environment combinations:

8 browsers

3 plug-ins

6 client operating systems

3 servers

3 server OS

1,296 combinations !

All-pairs testing is the solution : tests a significant subset of variables pairs.

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4.3.2 Black box techniques boundary value analysis

Boundaries = edges of the equivalence classes.

Boundary values = values at the edge and nearest to the edge

The steps for using boundary values:

First, identify the equivalence classes.

Second, identify the boundaries of each equivalence class.

Third, create test cases for each boundary value by choosing one point on the boundary, one point just below the boundary, and one point just above the

boundary. "Below" and "above" are relative terms and depend on the data

value's units

For the previous example:

boundary values are {-1,0,1}, {14,15,16},{15,16,17},{16,17,18}{17,18,19}, {54,55,56},{98, 99, 100}

Or, omitting duplicate values:

{-1,0,1,14,15,16,17,18,19,54,55,56,98,99,100}

(other examples)

(see Lee Copeland b2 chap.4, Paul Jorgensen b7 chap5)

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4.3.3 Black box techniques decision tables

Conditions represent various input conditions

Actions are the actions taken depending on the various combinations of input

conditions

Each of the rules defines a unique combination of conditions that result in the

execution of the actions associated with that rule

Actions do not depend on the condition evaluation order, but only on their

values.

Actions do not depend on any previous input conditions or system state.

(see Lee Copeland b2 chap 5, Paul Jorgensen b7 chap 7)

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4.3.3 Black box techniques decision tables - example

a, b, c are they the edges of a triangle?

(however, some additional test cases are needed)

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4.3.4 Black box techniques state transition tables

Allow the tester to interpret the system in term of:

States

Transition between states

Events that trigger transitions

Actions resulting from the transitions

Transition table used:

(see Lee Copeland b2, chap 7)

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4.3.4 Black box techniques state transition tables - example

Ticket buy - web application

Exercise: Fill-in the transition table!

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4.3.5 Black box techniques requirements based testing

Best practices:

Validate requirements (what) against objectives (why)

Apply use cases against requirements

Perform ambiguity reviews

Involve domain experts in requirements reviews

Create cause-effect diagrams

Check logical consistency of test scenarios

Validate test scenarios with domain experts and users

Walk through scenarios comparing with design documents

Walk through scenarios comparing with code

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4.3.5 Black box techniques scenario testing

Good scenario attributes:

Is based on a real story

Is motivating for the tester

Is credible

Involves an enough complex use of environment and data

Is easy to evaluate ( no need for external oracle)

How to create good test scenarios:

Write down real-life stories

List possible users, analyze their interests and objectives

Consider also inexperienced or ostile users

List system benefits and create paths to access those features

Watch users using old versions of the system or an analog system

Study complaints about other analog systems

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4.3.5 Black box techniques use case testing

Generating the Test Cases from the Use Cases

Steps:

1. Identify the use-case

scenarios.

2. For each scenario, identify one

or more test cases.

3. For each test case, identify the

conditions that will cause it to

execute.

4. Complete the test case by

adding data values.

(see example)

Most common test case mistakes:

1. Making cases too long

2. Incomplete, incorrect, or incoherent setup

3. Leaving out a step

4. Naming fields that changed or no longer exist

5. Unclear whether tester or system does action

6. Unclear what is a pass or fail result

7. Failure to clean up

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4.3.5 Black box techniques Syntax testing

Syntax testing = uses a model of the formally-defined syntax of the inputs to a

Component

The syntax is represented as a number of rules each of which defines the

possible means of production of a symbol in terms of sequences of, iterations

of, or selections between other symbols.

Here is a representation of the syntax for the floating point number, float in

Backus Naur Form (BNF) :

float = int "e" int.

int = ["+"|"-"] nat.

nat = {dig}.

dig = "0"|"1"|"2"|"3"|"4"|"5"|"6"|"7"|"8"|"9".

Syntax testing is the only black box technique without a coverage metric

assigned.

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4.4 White box techniques Control flow

Modules of code are converted to graphs, the paths through the graphs are analyzed, and

test cases are created from that analysis. There are different levels of coverage.

Process Blocks

A process block is a sequence

of program statements that

execute sequentially.

No entry into the block is

permitted except at the

beginning. No exit from the

block is permitted except at

the end. Once the block is

initiated, every statement

within it will be executed

sequentially.

Decision Point

A decision point is a point in the

module at which the control

flow can change. Most decision

points are binary and are

implemented by if-then-else

statements. Multi-way decision

points are implemented by

case statements. They are

represented by a bubble with

one entry and multiple exits.

Junction Point

A junction point is a point at

which control flows join

together

Example:

(see Lee Copeland b2, chap.10)

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4.4.1 White box techniques statement coverage

Statement coverage = Executed statements / Total executable statements

Example:

a;

if (b) {

c;

}

d;

In case b is TRUE, executing the code will result in 100% statement coverage

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4.4.1 White box techniques statement coverage - exercise

Given the code:

a;

if (x) {

b;

if (y) {

c;

}

else {

d;

}

}

else {

e;

}

How many test cases are needed to get 100% statement coverage?

x T T F F

y T F T F

a a a a

b b

c

d

e e

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4.4.2 White box techniques branch & decision coverage - glossary

Branch = a conditional transfer of control from a statement to any other statement

OR

= an unconditional transfer of control from a statement to any other

statement except the next statement;

Branch coverage = executed branches / total branches

Decision coverage = executed decisions outcomes / total decisions

For components with one entry point 100% Branch Coverage is equivalent to

100% Decision Coverage

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4.4.2 White box techniques branch & decision coverage - example

Decisions = B2, B3, B5 each with 2 outcomes = 3 * 2 = 6

Branches = (how many arrows?) = 10

Q1. What are the decision and branch coverage for (B1 B2 B9) ?

Q2. But for (B1->B2->B3->B4->B8->B2->B3->B5->B6->B8->B2-

>B3->B5->B7) ?

Answers: 1. 1/6, 2/10 2. 5/6, 9/10

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4.4.2 White box techniques LCSAJ coverage

LCSAJ = Linear Code Sequence and Jump

Defined by a triple, conventionally identified by line numbers in a source

code listing:

the start of the linear code sequencethe end of the linear code sequencethe target line to which control flow is transferred

LCSAJ coverage = executed LCSAJ sequences / total nr. of LCSAJ seq.

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4.4.3 White box techniques data flow coverage

Just as one would not feel confident about a program without executing every

statement in it as part of some test, one should not feel confident about a program

without having seen the effect of using the value produced by each and every

computation.

Data flow coverages:

All defs = Number of exercised definition-use pairs / Number of variable definitions

All c(omputation)-uses = Number of exercised definition- c-use pairs / Number of definition- c-use pairs

All p(redicate)-uses = Number of exercised definition- p-use pairs / Number of definition- p-use pairs

All uses = Number of exercised definition- use pairs / Number of definition- use pairs

Branch condition = Boolean operand values executed / Total Boolean operand values

Branch condition combination = Boolean operand values combinations executed / Total Boolean operand values combinations

(see Lee Copeland b2, chap.11)

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4.5 Exploratory testing

Exploratory testing = Concurrent test design, test execution, test logging

and learning, based on a quick test charter containing objectives, and executed

within delimited time-intervals

Uses structured approach to error guessing, based on experience,

available defect data, domain expertise

On-the-fly design of tests that attack these potential errors

Skill, intuition and previous experience is vital

Test strategy is built around:

The project environment

Quality criteria defined for the project

Elements of the product

Risk factors

See http://www.utest.com/webinars/exploratory-software-testing

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4.6 Choosing test techniques

Factors used to choose:

Product or system type

Standards

Products requirements Available documentation

Determined risks

Schedule constraints

Cost constraints

Used software development life cycle model

Testers skills and (domain) experience

(additional materials: Unit Test design, exercises)

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5.1.1 Test organization & independence

Options : independent team or not?

Pluses:

Testers are not influenced by the other project members

Can act as the customers voice

More objectivity in evaluating the product quality issues

Minuses:

Risk of isolation from the development team

Communication issues

Developers can loose the quality ownership attribute

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5.1.2 Tasks of the test leader

Plan, estimates test effort, collaborates with project manager

Elaborates the test strategy

Initiate test specification, implementation, execution

Set-up configuration management of test environment & deliverables

Monitors and controls the execution of tests

Chooses suitable test metrics

Decides if and to what degree to automate the tests

Select tools

Schedule tests

Prepare summary test reports

Evaluate test measurements

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5.1.2 Tasks of the tester

Test Analyst

Identify test objectives (targets)

Review product requirements and

software specifications

Review test plans and test cases

Verifies requirements to test cases

traceability

Define test scenario details

Compares test results with test

oracle

Assesses test risks

Gather test measures

Test Designer

Define test approach (procedure)

Structure test implementation

Elaborates test case lists and

writes main test cases

Assesses testability

Define testing environment details

Tester

Define test approach (procedure)

Write test cases

Review test cases (peer review)

Implement and execute tests

Record defects, prepare defect reports

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5.2.1-5.2.2-5.2.3 Test planning

Test plan = A document describing the scope, approach, resources and schedule of

intended test activities

It identifies amongst others test items, the features to be tested, the testing tasks, who

will do each task, degree of tester independence, the test environment, the test design

techniques and test measurement techniques to be used, and the rationale for their

choice, and any risks requiring contingency planning.

It is a record of the test planning process

IEEE 829: Test plan contents:

Test plan identifierIntroductionTest itemsFeatures to be testedFeatures not to be testedApproachItem pass / fail criteriaSuspension criteria & resumption criteria

Test deliverablesTesting tasksEnvironmentResponsibilitiesStaffing and training needsSchedulesRisks and contingenciesApprovals

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5.2.1-5.2.2-5.2.3 Test planningDetermine scopeo Study project documents, used

software life-cycle specifications, product

desired quality attributeso Identify and communicate with other

stakeholderso Clarify test process expectations

Determine riskso Choose quality risk analysis method

(e.g. FMEA)o Document the list of risks,

probability, impact, priority, identify

mitigation actions

Estimate testing effort, determine costs,

develop scheduleo Define necessary roles

o Decompose test project into phases

and tasks (WBS)o Schedule tasks, assign resources,

set-up dependencieso Develop a budget

o Obtain commitment for the plan

from the stakeholders

Refine plano Define roles detailed

responsibilities

o Select test strategy, test levels:

Test strategy issues (alternatives):

Preventive approach

Reactive approach

Risk-based

Model (standard) based

Choosing testing techniques (white

and/or black box)

o Select metrics to be used for defect

tracking, coverage, monitoring

o Define entry and exit criteria

Exit criteria:

Coverage measures

Defect density or trend measures

Cost

Residual risk estimation

Time or market based

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5.2.4 Test estimation

Two approaches:

based on metrics (historical data)

made by domain experts

Testing effort depends on:

product characteristics (complexity, specification)

development process (team skills, tools, time factors)

defects discovered and rework involved

failure risk of the product (likelihood, impact)

Time for confirmation testing and regression testing must be

considered too

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5.2.5 Test strategiesTest approach (test strategy) = The chosen approaches and decisions made that follow from the

test project's and test team's goal or mission.

The mission is typically effective and efficient testing, and the strategies are the general policies,

rules, and principles that support this mission. Test tactics are the specific policies, techniques,

processes, and the way testing is done.

One way to classify test approaches or strategies is based on the point in time at which the bulk of

the test design work is begun:

Preventative approaches, where tests are designed as early as possible.

Reactive approaches, where test design comes after the software or system has been produced.

Or, another taxonomy:

Analytical - such as risk-based

testing

Model-based - such as stochastic

testing

Methodical - such as failure-

based, experience-based

Process- or standard-compliant

Dynamic and heuristic - such as

exploratory testing

Consultative

Regression-averse

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5.3 Test progress monitoring, reporting & control

Monitoring - Test metrics used:

Test cases (% passed/ % failed)

Defects (found, fixed/found, density, trends)

Test Coverage (% executed Test cases)

Reporting:

Defects remaining

Coverage metrics

Identified risks

Control: identify and implement

corrective actions for:

Testing processOther software life-cycle activities

Possible corrective actions:

Assign extra resourceRe-allocate resourceAdjust the test scheduleArrange for extra test environments

Refine the completion criteria

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5.4 Configuration management

IEEE definition of Configuration Management:

A discipline applying technical and administrative direction and surveillance to:

identify and document the functional and physical characteristics of aconfiguration item,

control changes to those characteristics, record and report change processing and implementation status, and verify compliance with specified requirements

Configuration Management:

identifies the current configuration (hardware, software) in the life cycle of the system, together with any changes that are in course of being

implemented.

provides traceability of changes through the lifecycle of the system. permits the reconstruction of a system whenever necessary

Only persistent objects must be subject to Configuration Management,

therefore, the data processed by a system cannot be placed under

Configuration Management.

Related to Version Control and Change Control

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5.4 Configuration management

Configuration Management activities:

Configuration identification = selecting the configuration items for a system

and recording their functional and physical characteristics in technical

documentation

Configuration control = evaluation, co-ordination, approval or disapproval, and

implementation of changes to configuration items after formal establishment of

their configuration identification

Status accounting = recording and reporting of information needed to manage

a configuration effectively, including:

a listing of the approved configuration identification, the status of proposed changes to the configuration, and the implementation status of the approved changes

Configuration auditing = The function to check that the software product

matches the configuration items identified previously

94

5.4 Configuration management

In Testing, Configuration Management must:

Identify all test-ware items

Establish and maintain the integrity of the testing deliverables (test plans, test cases, documentation) through the project life

cycle

Set and maintain the version of these items

Track the changes of these items

Relate test-ware items to other software development items in order to maintain traceability

Reference clearly all necessary documents in the test plans and test cases

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5.5 Risk & Testing

Risk = a factor that could result in future negative consequences,

expressed as likelihood and impact

Project risks (supplier related, organizational, technical)

Product risks (defects delivered, poor quality attributes (reliability,

usability, performance)

The risks identified can be used to:

Define the test strategy and techniques to be used

Define the extent and depth of testing

Prioritize test cases and procedures (find important defects early)

Determine if review or training activities could help

96

5.6 Incident management

Incident = any significant, unplanned event that occurs during testing that

requires subsequent investigation and / or correction

The system does not function as expectedActual results differ from expected resultsRequired features are missing

Incident reports can be raised against:

documents placed under review processproducts defects related to functional & non-functional requirementsdocumentation anomalies (manuals, on-line help)test-ware defects (errors in test cases or test procedures)

The incident reports raised against products defects are named also bug

reports.

97

5.6 Incident management

Recommended Bug report format

Defect ID

Component name and Build version

Reported by and Date

Error type

Severity

Priority

Summary and detailed description

Attached documents

(Exercise)

Bug statuses

Issued just been reported

Opened programmer is working to solve-it

Fixed programmer thinks thats repaired

Not solved tester retested but the bug is not solved

Deferred programmer or PM decided to postpone the decision

Not-a-bug programmer or tester discovered that it is not a defect

Closed bug is solved and verified

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6.1.1 Test tool classification

Management of testing:

Test management

Requirements management

Bug tracking

Configuration management

Static testing:

Review support

Static analysis

Modeling

Test specification:

Test design

Test data preparation

Test execution:

Record and play

Unit test framework

Result comparators

Coverage measurement

Security

Performance and monitoring:

Dynamic analysis

Load and stress testing

Monitoring

Specific application areas (TTCN-3)

Other tools

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6.1.2 Tool support - Management of testing

Test management:

Manage testing activities

Manage test-ware traceability

Test result reporting

Test metrics tools

Requirements management:

Checking

Traceability

Coverage

Bug tracking

Configuration management

Individual support:

Version and change control

Builder

Project related

Department or company related

Try TestLink (free, open source! )

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6.1.3 Tool support - Static testing

Review support:

Process support

Communications support

Team support

Static analysis:

Coding standards

WEB site structure

Metrics

Modeling:

SQL database management

101

6.1.4 Tool support Test specification

Test design:

From requirements

From design models

Test stubs and driver generators

Test data preparation

102

6.1.5 Tool support Test execution and logging

Record and play

Scripting

Unit test framework

Test harness frameworks

Result comparators

Coverage measurement

Security testing support

103

6.1.6 Tool support Performance and monitoring

Dynamic analysis:

Time dependencies

Memory leaks

Load testing

Stress testing

Monitoring

Watch for possible mistakes!

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6.2.1 Tool support benefits

Repetitive work is reduced (e.g. running regression tests, re-entering the same test data, and checking against coding standards).

Greater consistency and repeatability (e.g. tests executed by a tool, and tests derived from requirements).

Objective assessment (e.g. static measures, coverage and system behavior).

Ease of access to information about tests or testing (e.g. statistics and graphs about test progress, incident rates and performance).

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6.2.1 Tool support risks

Unrealistic expectations for the tool (including functionality and ease of use).

Underestimating the time, cost and effort for the initial introduction of a tool (including training and external expertise).

Underestimating the time and effort needed to achieve significant and continuing benefits from the tool (including the need for changes in the

testing process and continuous improvement of the way the tool is used).

Underestimating the effort required to maintain the test assets generated by the tool.

Over-reliance on the tool (replacement for test design or where manual testing would be better).

Lack of a dedicated test automation specialist

Lack of good understanding and experience with the issues of test automation

Lack of stakeholders commitment for the implementation of a such tool

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6.2.2 Tool support special considerations

Test execution tools:

Significant implementation effort

Record and play tools are instable when changes occur

Technical expertise is mandatory

Performance testing tools:

Expertise in design and results interpretation are mandatory

Static analysis tools:

Lots of warnings generated

Build management sensitive

Test management tools:

Interfacing with other tools (Windows Office, at least) is critical

Test tools future is much debated (see)

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6.2.2 Test automation classic mistakes (Shrini Kulkarni )

10. Wild Desire to automate 100%

9.Attempting to automate existing test cases without scrutinizing

them for suitability to automate8. Mapping test case to script 1:1 linear model falling prey to deceptive traceability and gold plated reporting.

7.Not building automation solution bottom-up , unidentifiable

building block of the solution.

6. Trying only one type of automation or attacking only one layer

of the application Farther you go from code, messier it gets.5. Focusing only test execution related tasks

4. Treating automation as scripting ignoring generally accepted good software development practices for hygiene.

3. Failure to involve developers from the beginning Not attempting to testability or automatability of the application.

2. Jumping to automation to speed up testing or save cost before

fixing testing problems inadequate, inefficient and broken.1. Failure to arrive (formulate) at the right mix of human testing

and automated test execution.

0. Using Automation as solution to testing problems.

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6.2.2 Tool support testing in Visual Studio Team System

Developer:

use Test Driven Development methods

manage Unit Testing

analyze code coverage

use code static analysis

use code profiler to handle performance issues

Tester:

manage test cases

manage test suites

manage manual testing

manage bug tracking

record / play WEB tests

run load tests

report test results

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6.2.2 Tool support testing in Agile distributed environment

http://agile2008toronto.pbwiki.com/Evolution+of+tools+and+practices+of+a+distributed+agile+team

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6.2.2 Introducing a tool into an organization

Tool selection process:

Identify requirements

Identify constraints

Check available tools on the market (feature evaluation)

Evaluate short list (feature comparison):

Demos

Quick pilots

Select a tool

Note: there are many free testing tools available, some of them also online

( www.testersdesk.com )

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ISTQB Foundation Exam guidelines

40 multiple (4) choice questions 1 hour exam

Score >= 65% (>=26 good answers) to pass

50% K1, 30% K2, 20% K3Chapter 1 - 7 questions Chapter 2 6 questions Chapter 3 3 questions Chapter 4 12 questions Chapter 5 8 questions Chapter 6 4 questions

K1: The candidates will recognize, remember

and recall a term or concept.

K2: The candidates can select the reasons or

explanations for statements related to the topic.

They can summarize, compare, classify and

give examples for concepts of testing.

K3: The candidates can select the correct

application of a concept or techniques and/or

apply it to a given context.

Example: (see others)Which statement regarding testing is correct?

a) Testing is planning, specifying and executing a program with the aim of

finding defects

b) Testing is the process of correcting defects identified in a developed

program

c) Testing is to localize, analyze and correct the direct defect cause

d) Testing is independently reviewing a system against its requirements