Test Principles and Concepts

1
Test Principles and Concepts

• Domain 1

2
Key Components

• Why do we test software
• Understanding the testing challenge
• Structural versus functional techniques
• Quality principles
• Life cycle testing
• The people challenges of software testing

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Why Do We Test Software?

• What is a defect?
• What is quality software?
• ITs view - means meeting requirements
• Users of software view - means fit for use
• The two software quality gaps
• User gap
• IT gap
• What is a defect to a software tester?

4
Why Does a Development Process Produce Defects?

• Variability is the enemy of quality the
  concepts behind maturing a software development
  process is to reduce variability.
• What does it mean for a process to be in or out
  of control?
• Special causes of variation
• Common causes of variation

5
Reducing the Frequency of Defects in Software
Development

• Five levels of maturity
• Ad hoc
• Control
• Core competency
• Predictable
• Innovative
• Testers need to understand process maturity

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An Effective Development Process that Minimizes
Defects Incorporates

• The concept of quality
• Reducing variability
• Reducing or eliminating defects

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PDCA View of a Process

• P - Devise a plan
• D - Execute (do) the plan
• C - Check the results
• A - Take the necessary action

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Workbench View of a Process

• Each workbench is built on the following two
  components
• Objective why the process exists
• People skills roles, responsibilities and
  associated skill sets needed to execute a process

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Workbench Components

• Inputs
• Procedures
• Deliverables
• Standards
• Tools

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Why do we test software The Answer

• We test software because the processes to build
  software are defect-prone
• Traditional way of software testing identifies
  where the specification has been incorrectly
  implemented, incompletely implemented or is
  missing
• Software testing compensates for the fact that
  the software development process does not
  identify the true needs of the user

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• Software testing can add significant value to the
  IT organization.
• Finding defects early costs considerably less
• Remove defects before going into production
• Identify weaknesses in development process so
  that those processes can be improved
• Mature processes produce software more
  effectively and efficiently

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Understanding the Testing Challenge

• Test Objectives
• A testing Goal
• Enable test manager and project manager to gauge
  testing progress and success
• Enhance communication within and without project
  team by defining scope of test effort
• Statement of the objective expected results
• Created from system requirements document
• Use a checklist to ensure process is followed

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Strategic Risks

• A risk is a condition that can result in a loss
• We cannot eliminate risks, but we can reduce
  their occurrence and/or impact of the loss
• One of the most effective methods to reduce
  computer system strategic risk is testing

14
Economics of Testing

• Most problems associated with testing occur from
  one of the following causes
• Failing to define testing objectives
• Testing at the wrong phase of the life cycle
• Using ineffective test techniques

15
Testing Policy

• Definition of testing
• Testing system
• Evaluation
• Standards

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What Are You Testing For?

• Why are defects hard to find?
• Not looking
• Looking, but not seeing
• Corrected condition causes another defect
• Life cycle testing

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Verification and Validation

• Verification ensures that the system (software,
  hardware, documentation and personnel) complies
  with the organizations standards and processes
• Answers question Did we build the right system?
  
• Validation physically ensures that the system
  operates according to plan by executing the
  system functions through a series of tests that
  can be observed and evaluated
• Answers question Did we build the system right?

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Functional and Structural Testing

• Functional testing
• Advantages
• Simulates actual system usage
• Makes no system structure assumptions
• Disadvantages
• Potential of missing logical errors in software
• Possibility of redundant testing
• Structural testing
• Advantages
• You can test the softwares structure logic
• You test code that you wouldnt use if you
  preformed only functional testing
• Disadvantages
• Does not ensure that youve met user requirements
• Its tests may not mimic real-world situations

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Testing Techniques

• White-box testing
• Statement coverage
• Decision coverage
• Condition coverage
• Decision/condition coverage
• Multiple condition coverage
• Black-box testing
• Equivalence partitioning
• Boundary analysis
• Error guessing
• Incremental testing
• Top-down
• Bottom-up
• Thread testing
• Independent testing
• Regression testing

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Reviews and Inspections

• Three types of reviews
• In-process
• Decision-point or phase-end
• Post implementation
• Three classes of reviews
• Informal or peer
• Semiformal or walkthroughs
• Formal or inspections

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Structural System Testing Techniques

• Stress
• Execution
• Recovery
• Operations
• Compliance (to process)
• Security

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Functional System Testing Techniques

• Requirements
• Regression
• Error handling
• Manual support
• Intersystem
• Control
• Parallel

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Quality Principles

• What is Quality?
• Five perspectives of quality
• Transcendent I know it when I see it
• Product-based Possesses desired features
• User-based Fitness for use
• Development- and manufacturing-based Conforms
  to requirements
• Value-based At an acceptable cost

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Definitions of Quality

• Frequently defined as meeting the customers
  requirements the first time and every time
• Conformance to a set of customer requirements
  that, if met, result in a product that is fit for
  its intended use
• Much more than the absence of defects
• Requires controlled process improvement
• Can only be seen through the eyes of the
  customers

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Why Quality

• Cost of poor quality
• Quality philosophies
• Deming philosophy
• Michael Tveites regrouping of Demings 14 points
• Jurans ten steps to quality improvement
• Cost of quality
• Prevention costs
• Appraisal costs
• Failure costs

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Quality Assurance versus Quality Control

• Definitions
• Quality assurance is a planned and systematic set
  of activities necessary to provide adequate
  confidence that products and services will
  conform to specified requirements and meet user
  needs. Staff function.
• Quality control is the process by which product
  quality is compared with applicable standards,
  and the action taken when nonconformance is
  detected. Line function

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Life Cycle Testing

• Requirements
• Design
• Program (build/construction)
• Test process
• Installation
• Maintenance

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Quality Factors

• Correctness
• Authorization
• File Integrity
• Audit Trail
• Continuity of Processing
• Service Levels

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Developing a Test Plan

• Select and rank quality factors
• Identify the system development phases
• Identify the business risks associated with the
  system under development
• Place risks in the matrix

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Type of Development Methodology Impacts the Test
Plan

• Traditional system development (and most major
  changes to existing software systems
• Iterative development/prototyping/CASE
• System maintenance
• Purchased/contracted software

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People Challenges of SoftwareTesting

• Negative view of testing and testers
• Testers hold up implementation
• Top ten people challenges
• Training in testing
• Relationship building with developers
• Using tools
• Getting managers to understand testing
• Communicating with users about testing
• Making the necessary time for testing
• Testing over the wall software
• Trying to hit a moving target
• Fighting a lose-lose situation
• Having to say no

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Raise Management Awareness of the Importance of
Testing

• Calculate costs of testing and ensure the costs
  are understood by management
• Show management ways that the testing costs can
  be reduced by using more effective techniques
• Relay other benefits of testing
• Show that test training is built into your own
  personal goals and objectives, and discuss your
  training needs with your immediate supervisor
• Collect and distribute articles about testing
• Inquire about the budget for testing
• Use creative means to enlighten management

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Model for Test Process Improvement

• Examine the organizations needs and business
  goals
• Conduct assessment
• Initiate process improvement
• Analyze assessment output and derive action plan
• Implement improvements
• Confirm improvements
• Sustain improvement gains
• Monitor performance