Verification and Validation

Verification:

The standard definition of Verification is: "Are we building the product RIGHT?"

Verification is a process that makes it sure that the software product is developed the right way. The software should confirm to its predefined specifications, as the product development goes through different stages, an analysis is done to ensure that all required specifications are met.

During the Verification, the work product is reviewed/examined personally by one ore more persons in order to find and point out the defects in it. This process helps in prevention of potential bugs, which may cause in failure of the project.

Validation:

Validation is a process of finding out if the product being built is right?

Whatever the software product is being developed, it should do what the user expects it to do. The software product should functionally do what it is supposed to, it should satisfy all the functional requirements set by the user. Validation is done during or at the end of the development process in order to determine whether the product satisfies specified requirements.

All types of testing methods are basically carried out during the Validation process. Test plan, test suits and test cases are developed, which are used during the various phases of Validation process. The phases involved in Validation process are: Code Validation/Testing, Integration Validation/Integration Testing, Functional Validation/Functional Testing, and System/User Acceptance Testing/Validation.

Activities included in Verification and Validation Process:

The two major V&V activities are reviews, including, inspections and walkthroughs, and testing.

Reviews:
Reviews are conducted during and at the end of each phase of the life cycle to determine whether established requirements, design concepts, and specifications have been met. Reviews consist of the presentation of material to a review board or panel. Reviews are most effective when conducted by personnel who have not been directly involved in the development of the software being reviewed.

Inspection:
Inspection involves a team of about 3-6 people, led by a leader, which formally reviews the documents and work product during various phases of the product development life cycle. The work product and related documents are presented in front of the inspection team, the members of which carry different interpretations of the presentation. The bugs that are detected during the inspection are communicated to the next level in order to take care of them.

Walkthroughs:
Walkthrough can be considered same as inspection without formal preparation (of any presentation or documentations). During the walkthrough meeting, the presenter/author introduces the material to all the participants in order to make them familiar with it. Even when the walkthroughs can help in finding potential bugs, they are used for knowledge sharing or communication purpose.

Testing:
Testing is the operation of the software with real or simulated inputs to demonstrate that a product satisfies its requirements and, if it does not, to identify the specific differences between expected and actual results. There are varied levels of software tests, ranging from unit or element testing through integration testing and performance testing, up to software system and acceptance tests.

Testing Definitions

Ad-hoc Testing:
It is done without any formal test plans and test cases. Tester should have a significant understanding of software before testing it. It is normally done by experienced tester who has got good knowledge of software to be tested.
This testing is also done where software has to be tested in a very less time constraint.

Exploratory Testing:
It is done by the tester who has got less or no knowledge about the software which they are going to test. They can use this testing to write test cases. This is done at the initial stage of testing. This is majorly done to know the flow of software.

Negative Testing:
Negative testing is testing the tool with improper inputs. Negative Testing is simple testing the application beyond and below of its limits. For ex:
1) We want to enter a name for that negative test can be first we enter numbers.
2) We enter some ASCII characters and we will check
3) First numbers and characters we will check
4) Name should have some minimum length below that we will check

Load Testing:
Analyze number of things in load testing few:

1. Response times - Do they appear consistent, or is there any degrade over a period of time/Are they higher than what is expected
2. Performance of the hardware components – Mid-tier server or the application server, http server, and the database server. The CPU utilization, JVM memory heap of the application server, and the CPU of database server are important for assessing the performance.

Software Integration Environment (SIT):
This includes:
a. Server Machine
b. Database Machine
c. Client Machine

In real world scenario, application is tested using different machines for performance and compatibility purposes.

Database Testing:
In DB testing we need to check for,

1. The field size validation.
2. Check constraints.
3. Indexes are done or not (for performance related issues)
4. Stored procedures
5. The field size defined in the application is matching with that in the db.

QA Life Cycle

It is a integrated system of methodology activity involving like planning, implementation, assessment, reporting and quality improvement to ensure that the process is of the type and quality needed and expected by the client/customer.

1. Test requirements,
2. Test planning,
3. Test design,
4. Test execution and Defect logging,
6. Test reports and acceptance,
7. Sign off.

Test Requirements
1. Requirement Specification documents
2. Functional Specification documents
3. Design Specification documents (use cases, etc)
4. Use case Documents
5. Test Trace-ability Matrix for identifying Test Coverage

Test Planning
1. Test Scope, Test Environment
2. Different Test phase and Test Methodologies
3. Manual and Automation Testing
4. Defect Mgmt, Configuration Mgmt, Risk Mgmt. Etc
5. Evaluation & identification? Test, Defect tracking tools

Test Design
1. Test Traceability Matrix and Test coverage
2. Test Scenarios Identification & Test Case preparation
3. Test data and Test scripts preparation
4. Test case reviews and Approval
5. Base lining under Configuration Management

Test Execution and Defect Tracking
1. Executing Test cases
2. Testing Test Scripts
3. Capture, review and analyze Test Results
4. Raised the defects and tracking for its closure

Test Reports and Acceptance
1. Test summary reports
2. Test Metrics and process Improvements made
3. Build release
4. Receiving acceptance

Signoff
Signoff template provides a checklist format for customer that can be used for reviewing a new system's functionality and other attributes before closing a purchase order or accepting a delivery. It includes checklist areas for functional tests, documentation reviews, issue recording, enhancement requests.

This form can be used standalone for this purpose, or it can be used as the short-form checklist and signoff form accompanying a written User Acceptance Test Plan or Beta Test Plan (see our templates for those 2 documents).

NOTE: This form can also be adapted for review and acceptance of any deliverable between a customer and a provider. Whether the deliverable is a recommendations report from consultants, a user manual from a technical publications firm, a physical hardware system, a software application, a plan for a marketing campaign, etc., this form can be used to list what's expected by the customer, record results of the acceptance review or tests, record open issues to be corrected, and ultimately document acceptance by the customer.

How to use?
When preparing to accept a deliverable—system, product, report, etc.—from a supplier, fill out your version of this form to include the items you want to test and/or review. If possible, consider ahead of time whether any discrepancies will be acceptable for each item. Schedule the review/tests with the supplier and discuss expectations. When you perform the reviews or tests, mark the performance of each item and indicate whether each result is acceptable—will the deliverable be accepted with this issue? Finally, review overall results with supplier, timeline for issue resolution, and whether re-test will be required.

Testing Glossary

Acceptance Testing: Testing conducted to enable a user/customer to determine whether to accept a software product. Normally performed to validate the software meets a set of agreed acceptance criteria.

Accessibility Testing: Verifying a product is accessible to the people having disabilities (deaf, blind, mentally disabled etc.).

Ad Hoc Testing: A testing phase where the tester tries to 'break' the system by randomly trying the system's functionality. Can include negative testing as well. See also Monkey Testing.

Agile Testing: Testing practice for projects using agile methodologies, treating development as the customer of testing and emphasizing a test-first design paradigm. See also Test Driven Development.

Application Binary Interface (ABI): A specification defining requirements for portability of applications in binary forms across defferent system platforms and environments.

Application Programming Interface (API): A formalized set of software calls and routines that can be referenced by an application program in order to access supporting system or network services.

Automated Software Quality (ASQ): The use of software tools, such as automated testing tools, to improve software quality.

Automated Testing:
* Testing employing software tools which execute tests without manual intervention. Can be applied in GUI, performance, API, etc. testing.
* The use of software to control the execution of tests, the comparison of actual outcomes to predicted outcomes, the setting up of test preconditions, and other test control and test reporting functions.

Backus-Naur Form: A metalanguage used to formally describe the syntax of a language.

Basic Block: A sequence of one or more consecutive, executable statements containing no branches.

Basis Path Testing: A white box test case design technique that uses the algorithmic flow of the program to design tests.

Basis Set: The set of tests derived using basis path testing.

Baseline: The point at which some deliverable produced during the software engineering process is put under formal change control.

Benchmark Testing: Tests that use representative sets of programs and data designed to evaluate the performance of computer hardware and software in a given configuration.

Beta Testing: Testing of a rerelease of a software product conducted by customers.

Binary Portability Testing: Testing an executable application for portability across system platforms and environments, usually for conformation to an ABI specification.

Black Box Testing: Testing based on an analysis of the specification of a piece of software without reference to its internal workings. The goal is to test how well the component conforms to the published requirements for the component.

Bottom Up Testing: An approach to integration testing where the lowest level components are tested first, then used to facilitate the testing of higher level components. The process is repeated until the component at the top of the hierarchy is tested.

Boundary Testing: Test which focus on the boundary or limit conditions of the software being tested. (Some of these tests are stress tests).

Boundary Value Analysis: In boundary value analysis, test cases are generated using the extremes of the input domaini, e.g. maximum, minimum, just inside/outside boundaries, typical values, and error values. BVA is similar to Equivalence Partitioning but focuses on "corner cases".

Branch Testing: Testing in which all branches in the program source code are tested at least once.

Breadth Testing: A test suite that exercises the full functionality of a product but does not test features in detail.

Bug: A fault in a program which causes the program to perform in an unintended or unanticipated manner.

CAST: Computer Aided Software Testing.

Capture/Replay Tool: A test tool that records test input as it is sent to the software under test. The input cases stored can then be used to reproduce the test at a later time. Most commonly applied to GUI test tools.

CMM: The Capability Maturity Model for Software (CMM or SW-CMM) is a model for judging the maturity of the software processes of an organization and for identifying the key practices that are required to increase the maturity of these processes.

Cause Effect Graph: A graphical representation of inputs and the associated outputs effects which can be used to design test cases.

Code Complete: Phase of development where functionality is implemented in entirety; bug fixes are all that are left. All functions found in the Functional Specifications have been implemented.

Code Coverage: An analysis method that determines which parts of the software have been executed (covered) by the test case suite and which parts have not been executed and therefore may require additional attention.

Code Inspection: A formal testing technique where the programmer reviews source code with a group who ask questions analyzing the program logic, analyzing the code with respect to a checklist of historically common programming errors, and analyzing its compliance with coding standards.

Code Walkthrough: A formal testing technique where source code is traced by a group with a small set of test cases, while the state of program variables is manually monitored, to analyze the programmer's logic and assumptions.

Coding: The generation of source code.

Compatibility Testing: Testing whether software is compatible with other elements of a system with which it should operate, e.g. browsers, Operating Systems, or hardware.

Component: A minimal software item for which a separate specification is available.

Concurrency Testing:Multi-user testing geared towards determining the effects of accessing the same application code, module or database records. Identifies and measures the level of locking, deadlocking and use of single-threaded code and locking semaphores.

Conformance Testing: The process of testing that an implementation conforms to the specification on which it is based. Usually applied to testing conformance to a formal standard.

Context Driven Testing: The context-driven school of software testing is flavor of Agile Testing that advocates continuous and creative evaluation of testing opportunities in light of the potential information revealed and the value of that information to the organization right now.

Conversion Testing: Testing of programs or procedures used to convert data from existing systems for use in replacement systems.

Cyclomatic Complexity: A measure of the logical complexity of an algorithm, used in white-box testing.

Data Dictionary: A database that contains definitions of all data items defined during analysis.

Data Flow Diagram: A modeling notation that represents a functional decomposition of a system.

Data Driven Testing: Testing in which the action of a test case is parameterized by externally defined data values, maintained as a file or spreadsheet. A common technique in Automated Testing.

Debugging: The process of finding and removing the causes of software failures.

Defect: Nonconformance to requirements or functional / program specification

Dependency Testing: Examines an application's requirements for pre-existing software, initial states and configuration in order to maintain proper functionality.

Depth Testing: A test that exercises a feature of a product in full detail.

Dynamic Testing: Testing software through executing it. See also Static Testing.

Emulator: A device, computer program, or system that accepts the same inputs and produces the same outputs as a given system.

Endurance Testing: Checks for memory leaks or other problems that may occur with prolonged execution.

End-to-End testing: Testing a complete application environment in a situation that mimics real-world use, such as interacting with a database, using network communications, or interacting with other hardware, applications, or systems if appropriate.

Equivalence Class: A portion of a component's input or output domains for which the component's behavior is assumed to be the same from the component's specification.

Equivalence Partitioning: A test case design technique for a component in which test cases are designed to execute representatives from equivalence classes.

Exhaustive Testing: Testing which covers all combinations of input values and preconditions for an element of the software under test.

Functional Decomposition: A technique used during planning, analysis and design; creates a functional hierarchy for the software.

Functional Specification: A document that describes in detail the characteristics of the product with regard to its intended features.

Functional Testing: same as Black Box Testing.
* Testing the features and operational behavior of a product to ensure they correspond to its specifications.
* Testing that ignores the internal mechanism of a system or component and focuses solely on the outputs generated in response to selected inputs and execution conditions.

Glass Box Testing: A synonym for White Box Testing.

Gorilla Testing: Testing one particular module,functionality heavily.

Gray Box Testing: A combination of Black Box and White Box testing methodologies: testing a piece of software against its specification but using some knowledge of its internal workings.

High Order Tests: Black-box tests conducted once the software has been integrated.

Independent Test Group (ITG): A group of people whose primary responsibility is software testing,

Inspection: A group review quality improvement process for written material. It consists of two aspects; product (document itself) improvement and process improvement (of both document production and inspection).

Integration Testing: Testing of combined parts of an application to determine if they function together correctly. Usually performed after unit and functional testing. This type of testing is especially relevant to client/server and distributed systems.

Installation Testing: Confirms that the application under test recovers from expected or unexpected events without loss of data or functionality. Events can include shortage of disk space, unexpected loss of communication, or power out conditions.

Localization Testing: This term refers to making software specifically designed for a specific locality.

Loop Testing: A white box testing technique that exercises program loops.

Metric: A standard of measurement. Software metrics are the statistics describing the structure or content of a program. A metric should be a real objective measurement of something such as number of bugs per lines of code.

Monkey Testing: Testing a system or an Application on the fly, i.e just few tests here and there to ensure the system or an application does not crash out.

Mutation Testing: Testing done on the application where bugs are purposely added to it.

Negative Testing: Testing aimed at showing software does not work. Also known as "test to fail". See also Positive Testing.

N+1 Testing: A variation of Regression Testing. Testing conducted with multiple cycles in which errors found in test cycle N are resolved and the solution is retested in test cycle N+1. The cycles are typically repeated until the solution reaches a steady state and there are no errors. See also Regression Testing.

Path Testing: Testing in which all paths in the program source code are tested at least once.

Performance Testing: Testing conducted to evaluate the compliance of a system or component with specified performance requirements. Often this is performed using an automated test tool to simulate large number of users. Also know as "Load Testing".

Positive Testing: Testing aimed at showing software works. Also known as "test to pass". See also Negative Testing.

Quality Assurance: All those planned or systematic actions necessary to provide adequate confidence that a product or service is of the type and quality needed and expected by the customer.

Quality Audit: A systematic and independent examination to determine whether quality activities and related results comply with planned arrangements and whether these arrangements are implemented effectively and are suitable to achieve objectives.

Quality Circle: A group of individuals with related interests that meet at regular intervals to consider problems or other matters related to the quality of outputs of a process and to the correction of problems or to the improvement of quality.

Quality Control: The operational techniques and the activities used to fulfill and verify requirements of quality.

Quality Management: That aspect of the overall management function that determines and implements the quality policy.

Quality Policy: The overall intentions and direction of an organization as regards quality as formally expressed by top management.

Quality System: The organizational structure, responsibilities, procedures, processes, and resources for implementing quality management.

Race Condition: A cause of concurrency problems. Multiple accesses to a shared resource, at least one of which is a write, with no mechanism used by either to moderate simultaneous access.

Ramp Testing: Continuously raising an input signal until the system breaks down.

Recovery Testing: Confirms that the program recovers from expected or unexpected events without loss of data or functionality. Events can include shortage of disk space, unexpected loss of communication, or power out conditions.

Regression Testing: Retesting a previously tested program following modification to ensure that faults have not been introduced or uncovered as a result of the changes made.

Release Candidate: A pre-release version, which contains the desired functionality of the final version, but which needs to be tested for bugs (which ideally should be removed before the final version is released).

Sanity Testing: Brief test of major functional elements of a piece of software to determine if its basically operational. See also Smoke Testing.

Scalability Testing: Performance testing focused on ensuring the application under test gracefully handles increases in work load.

Security Testing: Testing which confirms that the program can restrict access to authorized personnel and that the authorized personnel can access the functions available to their security level.

Smoke Testing: A quick-and-dirty test that the major functions of a piece of software work. Originated in the hardware testing practice of turning on a new piece of hardware for the first time and considering it a success if it does not catch on fire.

Soak Testing: Running a system at high load for a prolonged period of time. For example, running several times more transactions in an entire day (or night) than would be expected in a busy day, to identify and performance problems that appear after a large number of transactions have been executed.

Software Requirements Specification: A deliverable that describes all data, functional and behavioral requirements, all constraints, and all validation requirements for software/

Software Testing: A set of activities conducted with the intent of finding errors in software.

Static Analysis: Analysis of a program carried out without executing the program.

Static Analyzer: A tool that carries out static analysis.

Static Testing: Analysis of a program carried out without executing the program.

Storage Testing: Testing that verifies the program under test stores data files in the correct directories and that it reserves sufficient space to prevent unexpected termination resulting from lack of space. This is external storage as opposed to internal storage.

Stress Testing: Testing conducted to evaluate a system or component at or beyond the limits of its specified requirements to determine the load under which it fails and how. Often this is performance testing using a very high level of simulated load.

Structural Testing: Testing based on an analysis of internal workings and structure of a piece of software. See also White Box Testing.

System Testing: Testing that attempts to discover defects that are properties of the entire system rather than of its individual components.

Testability: The degree to which a system or component facilitates the establishment of test criteria and the performance of tests to determine whether those criteria have been met.

Testing:
* The process of exercising software to verify that it satisfies specified requirements and to detect errors.
* The process of analyzing a software item to detect the differences between existing and required conditions (that is, bugs), and to evaluate the features of the software item (Ref. IEEE Std 829).
* The process of operating a system or component under specified conditions, observing or recording the results, and making an evaluation of some aspect of the system or component.

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.

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.

Test Driver: A program or test tool used to execute a tests. Also known as a Test Harness.

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.

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.

Test Harness: A program or test tool used to execute a tests. Also known as a Test Driver.

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. Ref IEEE Std 829.

Test Procedure: A document providing detailed instructions for the execution of one or more test cases.

Test Scenario: Definition of a set of test cases or test scripts and the sequence in which they are to be executed.

Test Script: Commonly used to refer to the instructions for a particular test that will be carried out by an automated test tool.

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.

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.

Test Tools: Computer programs used in the testing of a system, a component of the system, or its documentation.

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.

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.

Total Quality Management: A company commitment to develop a process that achieves high quality product and customer satisfaction.

Traceability Matrix: A document showing the relationship between Test Requirements and Test Cases.

Usability Testing: Testing the ease with which users can learn and use a product.

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.

User Acceptance Testing: A formal product evaluation performed by a customer as a condition of purchase.

Unit Testing: Testing of individual software components.

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.

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.

Volume Testing: Testing which confirms that any values that may become large over time (such as accumulated counts, logs, and data files), can be accommodated by the program and will not cause the program to stop working or degrade its operation in any manner.

Walkthrough: A review of requirements, designs or code characterized by the author of the material under review guiding the progression of the review.

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.

Workflow Testing: Scripted end-to-end testing which duplicates specific workflows which are expected to be utilized by the end-user.

Software Testing

Software Testing is the process used to measure the quality of developed computer software. Usually, quality is constrained to such topics as correctness, completeness, security, but can also include more technical requirements as described under the ISO standard ISO 9126, such as capability, reliability, efficiency, portability, maintainability, compatibility, and usability. Testing is a process of technical investigation, performed on behalf of stakeholders, that is intended to reveal quality-related information about the product with respect to the context in which it is intended to operate. This includes, but is not limited to, the process of executing a program or application with the intent of finding errors. Quality is not an absolute; it is value to some person. With that in mind, testing can never completely establish the correctness of arbitrary computer software; testing furnishes a criticism or comparison that compares the state and behavior of the product against a specification. An important point is that software testing should be distinguished from the separate discipline of Software Quality Assurance (SQA), which encompasses all business process areas, not just testing.

There are many approaches to software testing, but effective testing of complex products is essentially a process of investigation, not merely a matter of creating and following routine procedure. One definition of testing is "the process of questioning a product in order to evaluate it", where the "questions" are operations the tester attempts to execute with the product, and the product answers with its behavior in reaction to the probing of the tester. Although most of the intellectual processes of testing are nearly identical to that of review or inspection, the word testing is also used to connote the dynamic analysis of the product—putting the product through its paces. Sometimes one therefore refers to reviews, walkthroughs or inspections as "static testing", whereas actually running the program with a given set of test cases in a given development stage is often referred to as "Dynamic Testing", to emphasize the fact that formal review processes form part of the overall testing scope.

Software Testing Fundamentals

Testing objectives include:
1. Testing is a process of executing a program with the intent of finding an error.
2. A good test case is one that has a high probability of finding an as yet undiscovered error.
3. A successful test is one that uncovers an as yet undiscovered error.

Testing should systematically uncover different classes of errors in a minimum amount of time and with a minimum amount of effort. A secondary benefit of testing is that it demonstrates that the software appears to be working as stated in the specifications. The data collected through testing can also provide an indication of the software's reliability and quality. But, testing cannot show the absence of defect -- it can only show that software defects are present.

Testing Start Process

When Testing should start:

Testing early in the life cycle reduces the errors. Test deliverables are associated with every phase of development. The goal of Software Tester is to find bugs, find them as early as possible, and make them sure they are fixed.
The number one cause of Software bugs is the Specification. There are several reasons specifications are the largest bug producer.
In many instances a Spec simply isn’t written. Other reasons may be that the spec isn’t thorough enough, its constantly changing, or it’s not communicated well to the entire team. Planning software is vitally important. If it’s not done correctly bugs will be created.

The next largest source of bugs is the Design, That’s where the programmers lay the plan for their Software. Compare it to an architect creating the blue print for the building, Bugs occur here for the same reason they occur in the specification. It’s rushed, changed, or not well communicated.

Coding errors may be more familiar to you if you are a programmer. Typically these can be traced to the Software complexity, poor documentation, schedule pressure or just plain dump mistakes. It’s important to note that many bugs that appear on the surface to be programming errors can really be traced to specification. It’s quite common to hear a programmer say, “ oh, so that’s what its supposed to do. If someone had told me that I wouldn’t have written the code that way.”
The other category is the catch-all for what is left. Some bugs can blamed for false positives, conditions that were thought to be bugs but really weren’t. There may be duplicate bugs, multiple ones that resulted from the square root cause. Some bugs can be traced to Testing errors.

Costs: The costs re logarithmic- that is, they increase tenfold as time increases. A bug found and fixed during the early stages when the specification is being written might cost next to nothing, or 10 cents in our example. The same bug, if not found until the software is coded and tested, might cost $1 to $10. If a customer finds it, the cost would easily top $100.

Testing Stop Process

When to Stop Testing:
This can be difficult to determine. Many modern software applications are so complex, and run in such as interdependent environment, that complete testing can never be done. "When to stop testing" is one of the most difficult questions to a test engineer. Common factors in deciding when to stop are:
• Deadlines (release deadlines, testing deadlines.)
• Test cases completed with certain percentages passed
• Test budget depleted
• Coverage of code/functionality/requirements reaches a specified point
• The rate at which Bugs can be found is too small
• Beta or Alpha Testing period ends
• The risk in the project is under acceptable limit.
Practically, we feel that the decision of stopping testing is based on the level of the risk acceptable to the management. As testing is a never ending process we can never assume that 100 % testing has been done, we can only minimize the risk of shipping the product to client with X testing done. The risk can be measured by Risk analysis but for small duration / low budget / low resources project, risk can be deduced by simply: -
• Measuring Test Coverage.
• Number of test cycles.
• Number of high priority bugs.

Test Strategy:

How we plan to cover the product so as to develop an adequate assessment of quality?
A good test strategy is:
• Specific
• Practical
• Justified

The purpose of a test strategy is to clarify the major tasks and challenges of the test project.

Test Approach and Test Architecture are other terms commonly used to describe what I’m calling test strategy.
Example of a poorly stated (and probably poorly conceived) test strategy:
"We will use black box testing, cause-effect graphing, boundary testing, and white box testing to test this product against its specification."

Test Strategy: Type of Project, Type of Software, when Testing will occur, Critical Success factors, Tradeoffs

Test Plan - Why
• Identify Risks and Assumptions up front to reduce surprises later.
• Communicate objectives to all team members.
• Foundation for Test Spec, Test Cases, and ultimately the Bugs we find.
Failing to plan = planning to fail.

Test Plan - What
• Derived from Test Approach, Requirements, Project Plan, Functional Spec., and Design Spec.
• Details out project-specific Test Approach.
• Lists general (high level) Test Case areas.
• Include testing Risk Assessment.
• Include preliminary Test Schedule
• Lists Resource requirements.

Test Plan

The test strategy identifies multiple test levels, which are going to be performed for the project. Activities at each level must be planned well in advance and it has to be formally documented. Based on the individual plans only, the individual test levels are carried out.
Entry means the entry point to that phase. For example, for unit testing, the coding must be complete and then only one can start unit testing. Task is the activity that is performed. Validation is the way in which the progress and correctness and compliance are verified for that phase. Exit tells the completion criteria of that phase, after the validation is done. For example, the exit criterion for unit testing is all unit test cases must pass.

Unit Test Plan {UTP}

The unit test plan is the overall plan to carry out the unit test activities. The lead tester prepares it and it will be distributed to the individual testers, which contains the following sections.

What is to be tested?
The unit test plan must clearly specify the scope of unit testing. In this, normally the basic input/output of the units along with their basic functionality will be tested. In this case mostly the input units will be tested for the format, alignment, accuracy and the totals. The UTP will clearly give the rules of what data types are present in the system, their format and their boundary conditions. This list may not be exhaustive; but it is better to have a complete list of these details.

Sequence of Testing
The sequences of test activities that are to be carried out in this phase are to be listed in this section. This includes, whether to execute positive test cases first or negative test cases first, to execute test cases based on the priority, to execute test cases based on test groups etc. Positive test cases prove that the system performs what is supposed to do; negative test cases prove that the system does not perform what is not supposed to do. Testing the screens, files, database etc., are to be given in proper sequence.

Basic Functionality of Units
How the independent functionalities of the units are tested which excludes any communication between the unit and other units. The interface part is out of scope of this test level. Apart from the above sections, the following sections are addressed, very specific to unit testing.
• Unit Testing Tools
• Priority of Program units
• Naming convention for test cases
• Status reporting mechanism
• Regression test approach
• ETVX criteria

Introduction

Software Engineers distinguish software faults from software failures. In case of a failure, the software does not do what the user expects. A fault is a programming error that may or may not actually manifest as a failure. A fault can also be described as an error in the correctness of the semantic of a computer program. A fault will become a failure if the exact computation conditions are met, one of them being that the faulty portion of computer software executes on the CPU. A fault can also turn into a failure when the software is ported to a different hardware platform or a different compiler, or when the software gets extended.

Software testing may be viewed as a sub-field of Software Quality Assurance but typically exists independently (and there may be no SQA areas in some companies). In SQA, software process specialists and auditors take a broader view on software and its development. They examine and change the software engineering process itself to reduce the amount of faults that end up in the code or deliver faster.

Regardless of the methods used or level of formality involved, the desired result of testing is a level of confidence in the software so that the organization is confident that the software has an acceptable defect rate. What constitutes an acceptable defect rate depends on the nature of the software. An arcade video game designed to simulate flying an airplane would presumably have a much higher tolerance for defects than software used to control an actual airliner.

A problem with software testing is that the number of defects in a software product can be very large, and the number of configurations of the product larger still. Bugs that occur infrequently are difficult to find in testing. A rule of thumb is that a system that is expected to function without faults for a certain length of time must have already been tested for at least that length of time. This has severe consequences for projects to write long-lived reliable software, since it is not usually commercially viable to test over the proposed length of time unless this is a relatively short period. A few days or a week would normally be acceptable, but any longer period would usually have to be simulated according to carefully prescribed start and end conditions.

A common practice of software testing is that it is performed by an independent group of testers after the functionality is developed but before it is shipped to the customer. This practice often results in the testing phase being used as project buffer to compensate for project delays, thereby compromising the time devoted to testing. Another practice is to start software testing at the same moment the project starts and it is a continuous process until the project finishes.

This is highly problematic in terms of controlling changes to software: if faults or failures are found part way into the project, the decision to correct the software needs to be taken on the basis of whether or not these defects will delay the remainder of the project. If the software does need correction, this needs to be rigorously controlled using a version numbering system, and software testers need to be accurate in knowing that they are testing the correct version, and will need to re-test the part of the software wherein the defects were found. The correct start point needs to be identified for retesting. There are added risks in that new defects may be introduced as part of the corrections, and the original requirement can also change part way through, in which instance previous successful tests may no longer meet the requirement and will need to be re-specified and redone (part of regression testing). Clearly the possibilities for projects being delayed and running over budget are significant.

Another common practice is for test suites to be developed during technical support escalation procedures. Such tests are then maintained in regression testing suites to ensure that future updates to the software don't repeat any of the known mistakes.

It is commonly believed that the earlier a defect is found the cheaper it is to fix it. This is reasonable based on the risk of any given defect contributing to or being confused with further defects later in the system or process. In particular, if a defect erroneously changes the state of the data on which the software is operating, that data is no longer reliable and therefore any testing after that point cannot be relied on even if there are no further actual software defects.

In counterpoint, some emerging software disciplines such as extreme programming and the agile software development movement, adhere to a "test-driven software development" model. In this process unit tests are written first, by the software engineers (often with pair programming in the extreme programming methodology). Of course these tests fail initially; as they are expected to. Then as code is written it passes incrementally larger portions of the test suites. The test suites are continuously updated as new failure conditions and corner cases are discovered, and they are integrated with any regression tests that are developed.