CS4311 Spring 2011

Verification & Validation

Dr. Guoqiang Hu

Department of Computer ScienceUTEP

Announcement

What: CS4390 (Cross-listed with CS5390): “Software Testing”

Testing Only, Nothing Else!

When: This Summer

Prerequisite: CS4311

* Note: The V&V content covered in this course (CS4311) can be considered as an introduction to the above course

What Are Verification and Validation?Groups of 2

Why? Who? What? Against what? When? How?

5 minutes

Verification:Evaluating the product (a system or component) of a development phase to determine whether the product satisfies the specification at the start of the phase.

Did we build the system or component right?

Validation:Evaluating the product (mostly the system or subsystem) during or at the end of the development process to determine whether it satisfies the specified requirements.

Did we build the right system?

V&V Activities and the Software Lifecycle

Requirements engineering:Determine general test strategy/plan(techniques, criteria, team)

Test requirements specification

• Completeness

• Consistency

• Feasibility

(Functional, performance requirements)

• Testability

(Specific; Unambiguous; Quantitative; Traceable)

Generate acceptance/validation testing data

Design:Determine integration test strategy

Assess/Test the design: Completeness; Consistency; Handling scenarios; Traceability (to and fro). (design walkthrough, inspection)

V&V Activities and the Software Lifecycle

Implementation:Determine unit test strategy

Techniques (Static v. Dynamic):

• Read/Have it read

• Code walkthrough/Formal code inspection

• Formal verification/Proof

• Manual testing

Tools, and whistles and bells (driver/harness, stub)

Maintenance:Determine regression test strategy

Documentation maintenance (vital)

V&V Activities and the Software Lifecycle

The “V” model:

Where Do the Errors Come From?Groups of 2

What kinds of errors? Who?

3 minutes

Kinds of errors:Missing information

Wrong information/design/implementation

Extra information

Facts about errors:To err is human (but different person has different error rate).

Different studies indicate 30 to 85 errors per 1000 lines. After extensive testing, 0.5 to 3 errors per 1000 lines remain.

The longer an error goes undetected, the more costly to correct.

Basic Concepts

Correct specification:Specification matches the client’s intent.

Correct program:Program matches its specification.

Error:A human activity that leads to the creation of a fault.

Fault/Bug:The physical manifestation of an error. It can cause a failure.

Failure:The state when a fault is encountered during execution.

Basic Concepts

Fault identification:Process of determining what fault caused a failure

Fault correction:Process of changing a system to remove a fault

Debugging:Process of finding and fixing program faults

Testing:Designing and executing tests. And (if bugs present) debugging.

Test case:A particular set of input and the expected output

Basic Concepts

Test set:A finite set of test cases working together with the same purpose

Test objective:The main goal for a particular test. Ex., finding faults/fault detection, or, demonstrating reliability/confidence building (no/low failure rate in normal use).

Test objective affects test strategy, test criteria, and test selection.

Test criteria:Specifies testing requirements/stopping rule/measurement. It is closely linked to test techniques. Ex., for coverage-based test techniques, 100% statements, or branches, coverage, or both.

The General Approaches of Verification & ValidationGroups of 2

How?

2 minutes

The Exhaustive Test Examples

Groups of 2

3 minutes

How many test cases are required?

How long will it take?

The Exhaustive Test Examples

Groups of 23 minutes

A

B

C

The Exhaustive Test Examples

Groups of 2

3 minutes

The Purpose of TestingThe purpose of testing is NOT to prove the program is correct

Instead, it is to find problems in the program so that the found problems can be fixed

Interesting phenomena of testing results:Successful test:

The more faults are found, the more successful is a test case/ set.

Quality of the code:

The more faults are found in a unit of code, it normally means the worse is the quality of the code.

Studies found that more faults may still go undetected in the same piece of code.

Although you can say the quality of the code has been improved after the found faults are fixed.

Hierarchy of V&V techniques

V&V

Dynamic Techniques

Symbolic

ExecutionTesting

Informal

Analysis

Formal

Analysis

Static Techniques

Review

Inspection

Walkthrough

Hierarchy of TestingTesting

Program Testing

Top Down

Bottom Up

Integration Testing

Unit Testing

System Testing

Big Bang

Sandwich

Black Box

White Box

Function

Performance

Reliability

Availability

Acceptance

TestingProperties

Security

Equivalence

Boundary

Decision Table

State Transition

Use Case

Domain Analysis

Control Flow Data Flow

Usability

Documentation

Portability

Capacity

Ad hoc

Pilot

Alpha

Beta

Hierarchy of TestingTesting

Program Testing

Top Down

Bottom Up

Integration Testing

Unit Testing

System Testing

Big Bang

Sandwich

Black Box

White Box

Function

Performance

Reliability

Availability

Acceptance

TestingProperties

Security

Equivalence

Boundary

Decision Table

State Transition

Use Case

Domain Analysis

Control Flow Data Flow

Usability

Documentation

Portability

Capacity

Ad hoc

PilotAlphaBeta

Types of System Testing

Function Testing: Integrated system performs specified function

• Scenarios

• Black-box techniques

Properties Testing: Integrated system tests against non-functional requirements

• Performance, Reliability, Security, Usability, etc.

• Performance: Stress test: maximum throughput

Overload test: exceed specification

Volume test: sustained large throughput

Response time Robustness: test things not specified, but quite possible

Recovery: crash, or, recoverable?

Acceptance Testing: Customers test system

• Pilot (initial, customer), Alpha test (in-house), Beta test (on-site)

Types of Faults (not exhaustive)

Algorithmic: algorithm or logic does not produce the proper output for the given input

Syntax: improper use of language constructs

Computation (precision): formula’s implementation wrong or result not to correct degree of accuracy

Documentation: documentation does not match what program does

Stress (overload): data structures filled past capacity

Capacity: system performance unacceptable as activity reaches its specified limit

Timing: coordinating of events not correct

Throughput: system does not perform at speed required

Recovery: failure encountered and does not recover (crashed)

Who Are Involved?

Professional/Third party testers: organize and run tests

Analysts: involved in system requirements definition and specification

Designers: involved in the design and understand proposed solution and solution’s constraints

Implementers: involved in the implementation and understand the constraints associated with implementation

Configuration management representative: arranges for changes to be made consistently across all artifacts

The Advice

View testing as part of the development process

Testing is the last line of defense: Errors indicate that there is a problem with the development process

Test Plan

Objectives of Test Plan:Facilitate task of testing (strategy):

• The scope, approach, resources, and schedule

• Test techniques

• Test criteria

• Test documentation requirements

• Avoid repetition

• Improve test coverage

• Improve test efficiency

• Provide structure for final tests

Improve communication about testing

Provide structure for:

• Organizing

• Scheduling

• Managing

Test Plan ReportTable of Contents

DOCUMENT CONTROL

Approval

Document Change Control

Distribution List

Change Summary

1. INTRODUCTION

1.1. Purpose

1.2. Scope

1.3. System Overview

1.4. Test Approach Overview

2. APPLICABLE REFERENCES

3. TESTING APPROACH

4. TEST SCHEDULE

5. TEST XX

3. TESTING APPROACH

Specify types of tests to be performed

List specific tests

Test descriptions are in section 5

May include

• Test Management Requirements: how testing is to be managed

• Personnel Requirements

• Hardware Requirements

• Software Requirements

• Cost

Section 5 and later

Test No.

Current Status (Passed / Failed / Pending)

Test title

Testing approach

Concluding Remarks

Testing Team

Date Completed:

Assignments

Lead: V&V

Due Date: Tuesday, April 19, 2011

Due Time: Midnight MDT