Software Testing Framework

Document version: 2.0

Table of Contents......................................................................................... 2

Revision History........................................................................................... 4

Testing Framework....................................................................................... 5

1.0 Introduction............................................................................................................................................ 5

1.2 Traditional Testing Cycle........................................................................ 5

2.0 Verification and Validation Testing Strategies............................................ 6

2.1 Verification Strategies........................................................................... 6

2.1.1 Review’s................................................................................... 7

2.1.2 Inspections............................................................................... 8

2.1.3 Walkthroughs........................................................................... 8

2.2 Validation Strategies............................................................................. 8

3.0 Testing Types............................................................................................................................................. 9

3.1 White Box Testing.................................................................................. 9

White Box Testing Types............................................................................... 9

3.1.1 Basis Path Testing.................................................................... 10

3.1.2 Flow Graph Notation................................................................ 10

3.1.3 Cyclomatic Complexity............................................................... 10

3.1.4 Graph Matrices........................................................................ 10

3.1.5 Control Structure Testing........................................................ 10

3.1.5.1 Condition Testing........................................................... 10

3.1.5.2 Data Flow Testing.......................................................... 10

3.1.6 Loop Testing...................................................................................... 10

3.1.6.1 Simple Loops......................................................................... 11

3.1.6.2 Nested Loops......................................................................... 11

3.1.6.3 Concatenated Loops................................................................ 11

3.1.6.4 Unstructured Loops................................................................. 11

3.2 Black Box Testing................................................................................. 11

Black Box Testing Types.............................................................................. 11

3.2.1 Graph Based Testing Methods..................................................... 11

3.2.2 Equivalence Partitioning........................................................... 11

3.2.3 Boundary Value Analysis........................................................... 12

3.2.4 Comparison Testing.................................................................. 12

3.2.5 Orthogonal Array Testing......................................................... 12

3.3 Scenario Based Testing (SBT)....................................................... 12

3.4 Exploratory Testing.................................................................... 13

4.0 Structural System Testing Techniques..................................................... 13

5.0 Functional System Testing Techniques..................................................... 13

4.0 Testing Phases....................................................................................................................................... 14

4.2 Unit Testing......................................................................................... 15

4.3 Integration Testing.............................................................................. 15

4.3.1 Top-down Integration............................................................... 15

4.3.2 Bottom-up Integration.............................................................. 15

4.4 Smoke Testing...................................................................................... 16

4.5 System Testing..................................................................................... 16

4.5.1. Recovery Testing..................................................................... 16

4.5.2. Security Testing...................................................................... 16

4.5.3. Stress Testing........................................................................ 16

4.5.4. Performance Testing................................................................ 16

4.5.5. Regression Testing.................................................................. 17

4.6 Alpha Testing....................................................................................... 17

4.7 User Acceptance Testing........................................................................ 17

4.8 Beta Testing........................................................................................ 17

5.0 Metrics........................................................................................................................................................... 17

6.0 Test Models................................................................................................................................................ 19

6.1 The ‘V’ Model........................................................................................ 19

6.2 The ‘W’ Model....................................................................................... 20

6.3 The Butterfly Model.............................................................................. 21

7.0 Defect Tracking Process............................................................................................................ 23

8.0 Test Process for a Project....................................................................................................... 24

9.0 Deliverables............................................................................................................................................ 25

Revision History

Version No.	Date	Author	Notes
1.0	August 6, 2003	Harinath	Initial Document Creation and Posting on web site.
2.0	December 15, 2003	Harinath	Renamed the document to Software Testing Framework V2.0 Modified the structure of the document. Added Testing Models section Added SBT, ET testing types.

Next Version of this framework would include Test Estimation Procedures and More Metrics.

Testing Framework

Through experience they determined, that there should be 30 defects per 1000 lines of code. If testing does not uncover 30 defects, a logical solution is that the test process was not effective.

1.0 Introduction

Testing plays an important role in today’s System Development Life Cycle. During Testing, we follow a systematic procedure to uncover defects at various stages of the life cycle.

This framework is aimed at providing the reader various Test Types, Test Phases, Test Models and Test Metrics and guide as to how to perform effective Testing in the project.

All the definitions and standards mentioned in this framework are existing one’s. I have not altered any definitions, but where ever possible I tried to explain them in simple words. Also, the framework, approach and suggestions are my experiences. My intention of this framework is to help Test Engineers to understand the concepts of testing, various techniques and apply them effectively in their daily work. This framework is not for publication or for monetary distribution.

If you have any queries, suggestions for improvements or any points found missing, kindly write back to me.

1.2 Traditional Testing Cycle

Let us look at the traditional Software Development life cycle. The figure below depicts the same.

Fig A Fig B

In the above diagram (Fig A), the Testing phase comes after the Coding is complete and before the product is launched and goes into maintenance.

But, the recommended test process involves testing in every phase of the life cycle (Fig B). During the requirement phase, the emphasis is upon validation to determine that the defined requirements meet the needs of the project. During the design and program phases, the emphasis is on verification to ensure that the design and programs accomplish the defined requirements. During the test and installation phases, the emphasis is on inspection to determine that the implemented system meets the system specification.

The chart below describes the Life Cycle verification activities.

Life Cycle Phase	Verification Activities
Requirements	Determine verification approach. Determine adequacy of requirements. Generate functional test data. Determine consistency of design with requirements.
Design	Determine adequacy of design. Generate structural and functional test data. Determine consistency with design
Program (Build)	Determine adequacy of implementation Generate structural and functional test data for programs.
Test	Test application system.
Installation	Place tested system into production.
Maintenance	Modify and retest.

Throughout the entire lifecycle, neither development nor verification is a straight-line activity. Modifications or corrections to a structure at one phase will require modifications or re-verification of structures produced during previous phases.

2.0 Verification and Validation Testing Strategies

2.1 Verification Strategies

The Verification Strategies, persons / teams involved in the testing, and the deliverable of that phase of testing is briefed below:

Verification Strategy	Performed By	Explanation	Deliverable
Requirements Reviews	Users, Developers, Test Engineers.	Requirement Review’s help in base lining desired requirements to build a system.	Reviewed and approved statement of requirements.
Design Reviews	Designers, Test Engineers	Design Reviews help in validating if the design meets the requirements and build an effective system.	System Design Document, Hardware Design Document.
Code Walkthroughs	Developers, Subject Specialists, Test Engineers.	Code Walkthroughs help in analyzing the coding techniques and if the code is meeting the coding standards	Software ready for initial testing by the developer.
Code Inspections	Developers, Subject Specialists, Test Engineers.	Formal analysis of the program source code to find defects as defined by meeting system design specification.	Software ready for testing by the testing team.

2.1.1 Review’s

The focus of Review is on a work product (e.g. Requirements document, Code etc.). After the work product is developed, the Project Leader calls for a Review. The work product is distributed to the personnel who involves in the review. The main audience for the review should be the Project Manager, Project Leader and the Producer of the work product.

Major reviews include the following:

1. In Process Reviews

2. Decision Point or Phase End Reviews

3. Post Implementation Reviews

Let us discuss in brief about the above mentioned reviews. As per statistics Reviews uncover over 65% of the defects and testing uncovers around 30%. So, it’s very important to maintain reviews as part of the V&V strategies.

In-Process Review

In-Process Review looks at the product during a specific time period of a life cycle, such as activity. They are usually limited to a segment of a project, with the goal of identifying defects as work progresses, rather than at the close of a phase or even later, when they are more costly to correct.

Decision-Point or Phase-End Review

This review looks at the product for the main purpose of determining whether to continue with planned activities. They are held at the end of each phase, in a semiformal or formal way. Defects found are tracked through resolution, usually by way of the existing defect tracking system. The common phase-end reviews are Software Requirements Review, Critical Design Review and Test Readiness Review.

· The Software Requirements Review is aimed at validating and approving the documented software requirements for the purpose of establishing a baseline and identifying analysis packages. The Development Plan, Software Test Plan, Configuration Management Plan are some of the documents reviews during this phase.

· The Critical Design Review baselines the detailed design specification. Test cases are reviewed and approved.

· The Test Readiness Review is performed when the appropriate application components are near completing. This review will determine the readiness of the application for system and acceptance testing.

Post Implementation Review

These reviews are held after implementation is complete to audit the process based on actual results. Post-Implementation reviews are also known as Postmortems and are held to assess the success of the overall process after release and identify any opportunities for process improvement. They can be held up to three to six months after implementation, and are conducted in a format.

There are three general classes of reviews:

1. Informal or Peer Review

2. Semiformal or Walk-Through

3. Format or Inspections

Peer Review is generally a one-to-one meeting between the author of a work product and a peer, initiated as a request for import regarding a particular artifact or problem. There is no agenda, and results are not formally reported. These reviews occur on an as needed basis throughout each phase of a project.

2.1.2 Inspections

A knowledgeable individual called a moderator, who is not a member of the team or the author of the product under review, facilitates inspections. A recorder who records the defects found and actions assigned assists the moderator. The meeting is planned in advance and material is distributed to all the participants and the participants are expected to attend the meeting well prepared. The issues raised during the meeting are documented and circulated among the members present and the management.

2.1.3 Walkthroughs

The author of the material being reviewed facilitates walk-Through. The participants are led through the material in one of two formats; the presentation is made without interruptions and comments are made at the end, or comments are made throughout. In either case, the issues raised are captured and published in a report distributed to the participants. Possible solutions for uncovered defects are not discussed during the review.

2.2 Validation Strategies

The Validation Strategies, persons / teams involved in the testing, and the deliverable of that phase of testing is briefed below:

Validation Strategy	Performed By	Explanation	Deliverable
Unit Testing.	Developers / Test Engineers.	Testing of single program, modules, or unit of code.	Software unit ready for testing with other system component.
Integration Testing.	Test Engineers.	Testing of integrated programs, modules, or units of code.	Portions of the system ready for testing with other portions of the system.
System Testing.	Test Engineers.	Testing of entire computer system. This kind of testing usually includes functional and structural testing.	Tested computer system, based on what was specified to be developed.
Production Environment Testing.	Developers, Test Engineers.	Testing of the whole computer system before rolling out to the UAT.	Stable application.
User Acceptance Testing.	Users.	Testing of computer system to make sure it will work in the system regardless of what the system requirements indicate.	Tested and accepted system based on the user needs.
Installation Testing.	Test Engineers.	Testing of the Computer System during the Installation at the user place.	Successfully installed application.
Beta Testing	Users.	Testing of the application after the installation at the client place.	Successfully installed and running application.

3.0 Testing Types

There are two types of testing:

Functional or Black Box Testing,
Structural or White Box Testing.

Before the Project Management decides on the testing activities to be performed, it should have decided the test type that it is going to follow. If it is the Black Box, then the test cases should be written addressing the functionality of the application. If it is the White Box, then the Test Cases should be written for the internal and functional behavior of the system.

Functional testing ensures that the requirements are properly satisfied by the application system. The functions are those tasks that the system is designed to accomplish.

Structural testing ensures sufficient testing of the implementation of a function.

3.1 White Box Testing

White Box Testing; also know as glass box testing is a testing method where the tester involves in testing the individual software programs using tools, standards etc.

Using white box testing methods, we can derive test cases that:

1) Guarantee that all independent paths within a module have been exercised at lease once,

2) Exercise all logical decisions on their true and false sides,

3) Execute all loops at their boundaries and within their operational bounds, and

4) Exercise internal data structures to ensure their validity.

Advantages of White box testing:

1) Logic errors and incorrect assumptions are inversely proportional to the probability that a program path will be executed.

2) Often, a logical path is not likely to be executed when, in fact, it may be executed on a regular basis.

3) Typographical errors are random.

White Box Testing Types

There are various types of White Box Testing. Here in this framework I will address the most common and important types.

3.1.1 Basis Path Testing

Basis path testing is a white box testing technique first proposed by Tom McCabe. The Basis path method enables to derive a logical complexity measure of a procedural design and use this measure as a guide for defining a basis set of execution paths. Test Cases derived to exercise the basis set are guaranteed to execute every statement in the program at least one time during testing.

3.1.2 Flow Graph Notation

The flow graph depicts logical control flow using a diagrammatic notation. Each structured construct has a corresponding flow graph symbol.

3.1.3 Cyclomatic Complexity

Cyclomatic complexity is a software metric that provides a quantitative measure of the logical complexity of a program. When used in the context of a basis path testing method, the value computed for Cyclomatic complexity defines the number for independent paths in the basis set of a program and provides us with an upper bound for the number of tests that must be conducted to ensure that all statements have been executed at lease once.

An independent path is any path through the program that introduces at least one new set of processing statements or a new condition.

Computing Cyclomatic Complexity

Cyclomatic complexity has a foundation in graph theory and provides us with extremely useful software metric. Complexity is computed in one of the three ways:

1. The number of regions of the flow graph corresponds to the Cyclomatic complexity.

2. Cyclomatic complexity, V(G), for a flow graph, G is defined as

V (G) = E-N+2

Where E, is the number of flow graph edges, N is the number of flow graph nodes.

3. Cyclomatic complexity, V (G) for a flow graph, G is also defined as:

V (G) = P+1

Where P is the number of predicate nodes contained in the flow graph G.

3.1.4 Graph Matrices

The procedure for deriving the flow graph and even determining a set of basis paths is amenable to mechanization. To develop a software tool that assists in basis path testing, a data structure, called a graph matrix can be quite useful.

A Graph Matrix is a square matrix whose size is equal to the number of nodes on the flow graph. Each row and column corresponds to an identified node, and matrix entries correspond to connections between nodes.

3.1.5 Control Structure Testing

Described below are some of the variations of Control Structure Testing.

3.1.5.1 Condition Testing

Condition testing is a test case design method that exercises the logical conditions contained in a program module.

3.1.5.2 Data Flow Testing

The data flow testing method selects test paths of a program according to the locations of definitions and uses of variables in the program.

3.1.6 Loop Testing

Loop Testing is a white box testing technique that focuses exclusively on the validity of loop constructs. Four classes of loops can be defined: Simple loops, Concatenated loops, nested loops, and unstructured loops.

3.1.6.1 Simple Loops

The following sets of tests can be applied to simple loops, where ‘n’ is the maximum number of allowable passes through the loop.

1. Skip the loop entirely.

2. Only one pass through the loop.

3. Two passes through the loop.

4. ‘m’ passes through the loop where m<n.

5. n-1, n, n+1 passes through the loop.

3.1.6.2 Nested Loops

If we extend the test approach for simple loops to nested loops, the number of possible tests would grow geometrically as the level of nesting increases.

1. Start at the innermost loop. Set all other loops to minimum values.

2. Conduct simple loop tests for the innermost loop while holding the outer loops at their minimum iteration parameter values. Add other tests for out-of-range or exclude values.

3. Work outward, conducting tests for the next loop, but keeping all other outer loops at minimum values and other nested loops to “typical” values.

4. Continue until all loops have been tested.

3.1.6.3 Concatenated Loops

Concatenated loops can be tested using the approach defined for simple loops, if each of the loops is independent of the other. However, if two loops are concatenated and the loop counter for loop 1 is used as the initial value for loop 2, then the loops are not independent.

3.1.6.4 Unstructured Loops

Whenever possible, this class of loops should be redesigned to reflect the use of the structured programming constructs.

3.2 Black Box Testing

Black box testing, also known as behavioral testing focuses on the functional requirements of the software. All the functional requirements of the program will be used to derive sets of input conditions for testing.

Black Box Testing Types

The following are the most famous/frequently used Black Box Testing Types.

3.2.1 Graph Based Testing Methods

Software testing begins by creating a graph of important objects and their relationships and then devising a series of tests that will cover the graph so that each objects and their relationships and then devising a series of tests that will cover the graph so that each object and relationship is exercised and error are uncovered.

3.2.2 Equivalence Partitioning

Equivalence partitioning is a black box testing method that divides the input domain of a program into classes of data from which test cases can be derived.

EP can be defined according to the following guidelines:

1. If an input condition specifies a range, one valid and one two invalid classes are defined.

2. If an input condition requires a specific value, one valid and two invalid equivalence classes are defined.

3. If an input condition specifies a member of a set, one valid and one invalid equivalence class are defined.

4. If an input condition is Boolean, one valid and one invalid class are defined.

3.2.3 Boundary Value Analysis

BVA is a test case design technique that complements equivalence partitioning. Rather than selecting any element of an equivalence class, BVA leads to the selection of test cases at the “edges” of the class. Rather than focusing solely on input conditions, BVA derives test cases from the output domain as well.

Guidelines for BVA are similar in many respects to those provided for equivalence partitioning.

3.2.4 Comparison Testing

Situations where independent versions of software be developed for critical applications, even when only a single version will be used in the delivered computer based system. These independent versions from the basis of a black box testing technique called Comparison testing or back-to-back testing.

3.2.5 Orthogonal Array Testing

The orthogonal array testing method is particularly useful in finding errors associated with region faults – an error category associated with faulty logic within a software component.

3.3 Scenario Based Testing (SBT)

Dr.Cem Kaner in “A Pattern for Scenario Testing” has explained scenario Based Testing in great detail that can be found at www.testing.com.

What is Scenario Based Testing and How/Where is it useful is an interesting question. I shall explain in brief the above two mentioned points.

Scenario Based Testing is categorized under Black Box Tests and are most helpful when the testing is concentrated on the Business logic and functional behavior of the application. Adopting SBT is effective when testing complex applications. Now, every application is complex, then it’s the teams call as to implement SBT or not. I would personally suggest using SBT when the functionality to test includes various features and functions. A best example would be while testing banking application. As banking applications require utmost care while testing, handling various functions in a single scenario would result in effective results.

A sample transaction (scenario) can be, a customer logging into the application, checking his balance, transferring amount to another account, paying his bills, checking his balance again and logging out.

In brief, use Scenario Based Tests when:

1. Testing complex applications.

2. Testing Business functionality.

When designing scenarios, keep in mind:

1. The scenario should be close to the real life scenario.

2. Scenarios should be realistic.

3. Scenarios should be traceable to any/combination of functionality.

4. Scenarios should be supported by sufficient data.

3.4 Exploratory Testing

Exploratory Tests are categorized under Black Box Tests and are aimed at testing in conditions when sufficient time is not available for testing or proper documentation is not available.

Exploratory testing is ‘Testing while Exploring’. When you have no idea of how the application works, exploring the application with the intent of finding errors can be termed as Exploratory Testing.

Performing Exploratory Testing

This is one big question for many people. The following can be used to perform Exploratory Testing:

Learn the Application.
Learn the Business for which the application is addressed.
Learn the technology to the maximum extent on which the application has been designed.
Learn how to test.
Plan and Design tests as per the learning.

4.0 Structural System Testing Techniques

The following are the structural system testing techniques.

Technique	Description	Example
Stress	Determine system performance with expected volumes.	Sufficient disk space allocated.
Execution	System achieves desired level of proficiency.	Transaction turnaround time adequate.
Recovery	System can be returned to an operational status after a failure.	Evaluate adequacy of backup data.
Operations	System can be executed in a normal operational status.	Determine systems can run using document.
Compliance	System is developed in accordance with standards and procedures.	Standards follow.
Security	System is protected in accordance with importance to organization.	Access denied.

5.0 Functional System Testing Techniques

The following are the functional system testing techniques.

Technique	Description	Example
Requirements	System performs as specified.	Prove system requirements.
Regression	Verifies that anything unchanged still performs correctly.	Unchanged system segments function.
Error Handling	Errors can be prevented or detected and then corrected.	Error introduced into the test.
Manual Support	The people-computer interaction works.	Manual procedures developed.
Intersystems.	Data is correctly passed from system to system.	Intersystem parameters changed.
Control	Controls reduce system risk to an acceptable level.	File reconciliation procedures work.
Parallel	Old systems and new system are run and the results compared to detect unplanned differences.	Old and new system can reconcile.

4.0 Testing Phases

4.2 Unit Testing

Goal of Unit testing is to uncover defects using formal techniques like Boundary Value Analysis (BVA), Equivalence Partitioning, and Error Guessing. Defects and deviations in Date formats, Special requirements in input conditions (for example Text box where only numeric or alphabets should be entered), selection based on Combo Box’s, List Box’s, Option buttons, Check Box’s would be identified during the Unit Testing phase.

4.3 Integration Testing

Integration testing is a systematic technique for constructing the program structure while at the same time conducting tests to uncover errors associated with interfacing. The objective is to take unit tested components and build a program structure that has been dictated by design.

Usually, the following methods of Integration testing are followed:

1. Top-down Integration approach.

2. Bottom-up Integration approach.

4.3.1 Top-down Integration

Top-down integration testing is an incremental approach to construction of program structure. Modules are integrated by moving downward through the control hierarchy, beginning with the main control module. Modules subordinate to the main control module are incorporated into the structure in either a depth-first or breadth-first manner.

The Integration process is performed in a series of five steps:
The main control module is used as a test driver and stubs are substituted for all components directly subordinate to the main control module.
Depending on the integration approach selected subordinate stubs are replaced one at a time with actual components.
Tests are conducted as each component is integrated.
On completion of each set of tests, another stub is replaced with the real component.
Regression testing may be conducted to ensure that new errors have not been introduced.

4.3.2 Bottom-up Integration

Button-up integration testing begins construction and testing with atomic modules (i.e. components at the lowest levels in the program structure). Because components are integrated from the button up, processing required for components subordinate to a given level is always available and the need for stubs is eliminated.

A Bottom-up integration strategy may be implemented with the following steps:
Low level components are combined into clusters that perform a specific software sub function.
A driver is written to coordinate test case input and output.
The cluster is tested.
Drivers are removed and clusters are combined moving upward in the program structure.

4.4 Smoke Testing

“Smoke testing might be a characterized as a rolling integration strategy”.

Smoke testing is an integration testing approach that is commonly used when “shrink-wrapped” software products are being developed. It is designed as a pacing mechanism for time-critical projects, allowing the software team to assess its project on a frequent basis.

The smoke test should exercise the entire system from end to end. Smoke testing provides benefits such as:

1) Integration risk is minimized.

2) The quality of the end-product is improved.

3) Error diagnosis and correction are simplified.

4) Progress is easier to asses.

4.5 System Testing

System testing is a series of different tests whose primary purpose is to fully exercise the computer based system. Although each test has a different purpose, all work to verify that system elements have been properly integrated and perform allocated functions.

The following tests can be categorized under System testing:

Recovery Testing.
Security Testing.
Stress Testing.
Performance Testing.

4.5.1. Recovery Testing

Recovery testing is a system test that focuses the software to fall in a variety of ways and verifies that recovery is properly performed. If recovery is automatic, reinitialization, checkpointing mechanisms, data recovery and restart are evaluated for correctness. If recovery requires human intervention, the mean-time-to-repair (MTTR) is evaluated to determine whether it is within acceptable limits.

4.5.2. Security Testing

Security testing attempts to verify that protection mechanisms built into a system will, in fact, protect it from improper penetration. During Security testing, password cracking, unauthorized entry into the software, network security are all taken into consideration.

4.5.3. Stress Testing

Stress testing executes a system in a manner that demands resources in abnormal quantity, frequency, or volume. The following types of tests may be conducted during stress testing;

· Special tests may be designed that generate ten interrupts per second, when one or two is the average rate.

· Input data rates may be increases by an order of magnitude to determine how input functions will respond.

· Test Cases that require maximum memory or other resources.

· Test Cases that may cause excessive hunting for disk-resident data.

· Test Cases that my cause thrashing in a virtual operating system.

4.5.4. Performance Testing

Performance tests are coupled with stress testing and usually require both hardware and software instrumentation.

4.5.5. Regression Testing

Regression testing is the re-execution of some subset of tests that have already been conducted to ensure that changes have not propagated unintended side affects.

Regression may be conducted manually, by re-executing a subset of al test cases or using automated capture/playback tools.

The Regression test suit contains three different classes of test cases:

· A representative sample of tests that will exercise all software functions.

· Additional tests that focus on software functions that are likely to be affected by the change.

· Tests that focus on the software components that have been changed.

4.6 Alpha Testing

The Alpha testing is conducted at the developer sites and in a controlled environment by the end-user of the software.

4.7 User Acceptance Testing

User Acceptance testing occurs just before the software is released to the customer. The end-users along with the developers perform the User Acceptance Testing with a certain set of test cases and typical scenarios.

4.8 Beta Testing

The Beta testing is conducted at one or more customer sites by the end-user of the software. The beta test is a live application of the software in an environment that cannot be controlled by the developer.

5.0 Metrics

Metrics are the most important responsibility of the Test Team. Metrics allow for deeper understanding of the performance of the application and its behavior. The fine tuning of the application can be enhanced only with metrics. In a typical QA process, there are many metrics which provide information.

The following can be regarded as the fundamental metric:

IEEE Std 982.2 - 1988 defines a Functional or Test Coverage Metric. It can be used to measure test coverage prior to software delivery. It provide a measure of the percentage of the software tested at any point during testing.

It is calculated as follows:

Function Test Coverage = FE/FT

Where

FE is the number of test requirements that are covered by test cases that were executed against the software

FT is the total number of test requirements

Software Release Metrics

The software is ready for release when:

1. It has been tested with a test suite that provides 100% functional coverage, 80% branch coverage, and 100% procedure coverage.

2. There are no level 1 or 2 severity defects.

3. The defect finding rate is less than 40 new defects per 1000 hours of testing

4. The software reaches 1000 hours of operation

5. Stress testing, configuration testing, installation testing, Naïve user testing, usability testing, and sanity testing have been completed

IEEE Software Maturity Metric

IEEE Std 982.2 - 1988 defines a Software Maturity Index that can be used to determine the readiness for release of a software system. This index is especially useful for assessing release readiness when changes, additions, or deletions are made to existing software systems. It also provides an historical index of the impact of changes. It is calculated as follows:

SMI = Mt - ( Fa + Fc + Fd)/Mt

Where

SMI is the Software Maturity Index value

Mt is the number of software functions/modules in the current release

Fc is the number of functions/modules that contain changes from the previous release

Fa is the number of functions/modules that contain additions to the previous release

Fd is the number of functions/modules that are deleted from the previous release

Reliability Metrics

Perry offers the following equation for calculating reliability.

Reliability = 1 - Number of errors (actual or predicted)/Total number of lines of executable code

This reliability value is calculated for the number of errors during a specified time interval.

Three other metrics can be calculated during extended testing or after the system is in production. They are:

MTTFF (Mean Time to First Failure)

MTTFF = The number of time intervals the system is operable until its first failure

MTBF (Mean Time Between Failures)

MTBF = Sum of the time intervals the system is operable

Number of failures for the time period

MTTR (Mean Time To Repair)

MTTR = sum of the time intervals required to repair the system

The number of repairs during the time period

6.0 Test Models

There are various models of Software Testing. Here in this framework I would explain the three most commonly used models:

1. The ‘V’ Model.

2. The ‘W’ Model.

3. The Butterfly Model

6.1 The ‘V’ Model

The following diagram depicts the ‘V’ Model

Coding

The diagram is self-explanatory. For an easy understanding, look at the following table:

SDLC Phase	Test Phase
1. Requirements	1. Build Test Strategy. 2. Plan for Testing. 3. Acceptance Test Scenarios Identification.
2. Specification	1. System Test Case Generation.
3. Architecture	1. Integration Test Case Generation.
4. Detailed Design	1. Unit Test Case Generation

6.2 The ‘W’ Model

The following diagram depicts the ‘W’ model:

The ‘W’ model depicts that the Testing starts from day one of the initiation of the project and continues till the end. The following table will illustrate the phases of activities that happen in the ‘W’ model:

SDLC Phase	The first ‘V’	The second ‘V’
1. Requirements	1. Requirements Review	1. Build Test Strategy. 2. Plan for Testing. 3. Acceptance (Beta) Test Scenario Identification.
2. Specification	2. Specification Review	1. System Test Case Generation.
3. Architecture	3. Architecture Review	1. Integration Test Case Generation.
4. Detailed Design	4. Detailed Design Review	1. Unit Test Case Generation.
5. Code	5. Code Walkthrough	1. Execute Unit Tests
		1. Execute Integration Tests.
		1. Regression Round 1.
		1. Execute System Tests.
		1. Regression Round 2.
		1. Performance Tests
		1. Regression Round 3
		1. Performance/Beta Tests

In the second ‘V’, I have mentioned Acceptance/Beta Test Scenario Identification. This is because, the customer might want to design the Acceptance Tests. In this case as the development team executes the Beta Tests at the client place, the same team can identify the Scenarios.

Regression Rounds are performed at regular intervals to check whether the defects, which have been raised and fixed, are re-tested.

6.3 The Butterfly Model

The testing activities for testing software products are preferable to follow the Butterfly Model. The following picture depicts the test methodology.

Fig: Butterfly Model

In the Butterfly model of Test Development, the left wing of the butterfly depicts the Test Analysis. The right wing depicts the Test Design, and finally the body of the butterfly depicts the Test Execution. How this exactly happens is described below.

Test Analysis

Analysis is the key factor which drives in any planning. During the analysis, the analyst understands the following:

· Verify that each requirement is tagged in a manner that allows correlation of the tests for that requirement to the requirement itself. (Establish Test Traceability)

· Verify traceability of the software requirements to system requirements.

· Inspect for contradictory requirements.

· Inspect for ambiguous requirements.

· Inspect for missing requirements.

· Check to make sure that each requirement, as well as the specification as a whole, is understandable.

· Identify one or more measurement, demonstration, or analysis method that may be used to verify the requirement’s implementation (during formal testing).

· Create a test “sketch” that includes the tentative approach and indicates the test’s objectives.

During Test Analysis the required documents will be carefully studied by the Test Personnel, and the final Analysis Report is documented.

The following documents would be usually referred:

1. Software Requirements Specification.

2. Functional Specification.

3. Architecture Document.

4. Use Case Documents.

The Analysis Report would consist of the understanding of the application, the functional flow of the application, number of modules involved and the effective Test Time.

Test Design

The right wing of the butterfly represents the act of designing and implementing the test cases needed to verify the design artifact as replicated in the implementation. Like test analysis, it is a relatively large piece of work. Unlike test analysis, however, the focus of test design is not to assimilate information created by others, but rather to implement procedures, techniques, and data sets that achieve the test’s objective(s).

The outputs of the test analysis phase are the foundation for test design. Each requirement or design construct has had at least one technique (a measurement, demonstration, or analysis) identified during test analysis that will validate or verify that requirement. The tester must now implement the intended technique.

Software test design, as a discipline, is an exercise in the prevention, detection, and elimination of bugs in software. Preventing bugs is the primary goal of software testing. Diligent and competent test design prevents bugs from ever reaching the implementation stage. Test design, with its attendant test analysis foundation, is therefore the premiere weapon in the arsenal of developers and testers for limiting the cost associated with finding and fixing bugs.

During Test Design, basing on the Analysis Report the test personnel would develop the following:

Test Plan.
Test Approach.
Test Case documents.
Performance Test Parameters.
Performance Test Plan.

Test Execution

Any test case should adhere to the following principals:

Accurate – tests what the description says it will test.
Economical – has only the steps needed for its purpose.
Repeatable – tests should be consistent, no matter who/when it is executed.
Appropriate – should be apt for the situation.
Traceable – the functionality of the test case should be easily found.

During the Test Execution phase, keeping the Project and the Test schedule, the test cases designed would be executed. The following documents will be handled during the test execution phase:

1. Test Execution Reports.

2. Daily/Weekly/monthly Defect Reports.

3. Person wise defect reports.

After the Test Execution phase, the following documents would be signed off.

1. Project Closure Document.

2. Reliability Analysis Report.

3. Stability Analysis Report.

4. Performance Analysis Report.

5. Project Metrics.

7.0 Defect Tracking Process

The Defect Tracking process should answer the following questions:

When is the defect found?

2. Who raised the defect?

3. Is the defect reported properly?

4. Is the defect assigned to the appropriate developer?

5. When was the defect fixed?

6. Is the defect re-tested?

7. Is the defect closed?

The defect tracking process has to be handled carefully and managed efficiently.

The following figure illustrates the defect tracking process:

Defect Classification

This section defines a defect Severity Scale framework for determining defect criticality and the associated defect Priority Levels to be assigned to errors found software.

The defects can be classified as follows:

Classification	Description
Critical	There is s functionality block. The application is not able to proceed any further.
Major	The application is not working as desired. There are variations in the functionality.
Minor	There is no failure reported due to the defect, but certainly needs to be rectified.
Cosmetic	Defects in the User Interface or Navigation.
Suggestion	Feature which can be added for betterment.

Priority Level of the Defect

The priority level describes the time for resolution of the defect. The priority level would be classified as follows:

Classification	Description
Immediate	Resolve the defect with immediate effect.
At the Earliest	Resolve the defect at the earliest, on priority at the second level.
Normal	Resolve the defect.
Later	Could be resolved at the later stages.

8.0 Test Process for a Project

In this section, I would explain how to go about planning your testing activities effectively and efficiently. The process is explained in a tabular format giving the phase of testing, activity and person responsible.

For this, I assume that the project has been identified and the testing team consists of five personnel: Test Manager, Test Lead, Senior Test Engineer and 2 Test Engineer’s.

SDLC Phase	Testing Phase/Activity	Personnel
1. Requirements	1. Study the requirements for Testability. 2. Design the Test Strategy. 3. Prepare the Test Plan. 4. Identify scenarios for Acceptance/Beta Tests	Test Manager / Test Lead
2. Specification	1. Identify System Test Cases / Scenarios. 2. Identify Performance Tests.	Test Lead, Senior Test Engineer, and Test Engineers.
3. Architecture	1. Identify Integration Test Cases / Scenarios. 2. Identify Performance Tests.	Test Lead, Senior Test Engineer, and Test Engineers.
4. Detailed Design	1. Generate Unit Test Cases	Test Engineers.

9.0 Deliverables

The Deliverables from the Test team would include the following:

1. Test Strategy.

2. Test Plan.

3. Test Case Documents.

4. Defect Reports.

5. Status Reports (Daily/weekly/Monthly).

6. Test Scripts (if any).

7. Metric Reports.

8. Product Sign off Document.

Thursday, 21 November 2013

Software Testing Frame Work