Week 2

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The University of Lahore

A “W4” Category University

CS-4349 Software Testing &

Implementation

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07/10/2020 2

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What is root-cause analysis?

To find real reason when we detect faults is called root

cause analysis.

When we detect failures, we might try to track them back to

their root cause, the real reason that they happened.

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Exercise

Root Cause Analysis

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1.1.5 Testing and quality

Q 1- What can be the ways of carrying root cause analysis? Way1:

__________________________________________________________ Way2:

__________________________________________________________

Q 2- An organization has a problem with printing repeatedly failing. Suggest some possible causes of this failure.

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1.1.5 Testing and quality

Q 3- These causes may happen because

__________________________________________________________ __________________________________________________________ __________________________________________________________

Q 4- What possible steps the software testers will take to design the software and resolve the printing failure and facilitate the users?

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Q-1 What are the ways of carrying root-cause

analysis?

1. Discussion

2. Involving group of people with brainstorming ideas

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Q-2

Suppose an organization has a problem with printing repeatedly failing. Some IT maintenance will sit together to examine the problem and they start by brainstorming all the possible causes of the failure.

Some of the cause they discover might be:

1. Printer runs out of supplies (ink or paper) 2. Printer driver software fails.

3. Printer room is too hot for the printer.

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Q-3

If we look at one of the causes “ printer runs out of

supplies, it may happen because:

ROOT CAUSE:

1. No one is responsible for checking printer ink/paper before use. 2. Staff not trained in looking after the printer.

3. No process for stock control and ordering.

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Summary

Root-cause analysis

is an important aspect of

quality assurance activities and testing

contributes by helping us to identify defect and

improve software quality as early as possible

before the software is in use.

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A “W” Category University Ranked Amongst The Top 550 Universities of The WORLD!

Exhaustive Testing

A test approach in which the test suit comprises all combinations of input values and preconditions.

How much testing should we do?

Test everything Test nothing Test some of the software

Testing Principle-Exhaustive testing is impossible

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EXAMPLE 1

How many tests would you need to do to completely

test a one-digit numeric field?

1. 10 possible valid numeric values (10 tests)

2. We need to ensure that all invalid values are rejected.

e.g. 26 uppercase letters, 26 lowercase letters, special

characters and blank space. Total tests would be 68.

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EXAMPLE 2

One screen has 15 input fields, each having 1

digit numeric field. How many test are required

to do?

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Exhaustive Testing

A test approach in which the test suit comprises all combinations of input values and preconditions.

How much testing should we do?

Test everything Test nothing Test some of the software

Testing Principle-Exhaustive testing is impossible

Testing everything is not feasible/possible.

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EXAMPLE 1

How many tests would you need to do to completely

test a one-digit numeric field?

1. 10 possible valid numeric values (10 tests)

2. We need to ensure that all invalid values are rejected.

e.g. 26 uppercase letters, 26 lowercase letters, special

characters and blank space. Total tests would be 68.

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EXAMPLE 2

One screen has 15 input fields, each having 1

digit numeric field. How many test are required

to do?

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TESTING

“Testing is a process rather than a single

activity-there are series of activities

involved.”

One of the activities is all life cycle activities. Testing

takes place throughout the software development life

cycle.

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Software Development Life Cycle

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1.2 What is testing?

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SYSTEM LIFE CYCLE

1. System life cycle is an organizational process of developing and maintaining systems.

2. It helps in establishing a system project plan.

3. System development life cycle means combination of various activities put together are referred as system development life cycle.

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Phases of software development cycle

1. Problem Recognition (System Study) 2. Feasibility Study

3. System Analysis 4. System Design

5. Coding /Implementation/Construction 6. Testing

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System Study

1. System study is the first stage of system development life cycle.

2. It gives a clear picture of what actually the physical system is? 3. System study is done in two phases.

In the first phase, the preliminary survey of the system is done which helps in identifying the scope of the system.

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4. After completing the system study, a system

proposal is prepared by the System Analyst (who

studies the system) and placed before the user.

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System Study (SUMMARY)

1. Problem identification and project initiation 2. Background analysis

3. Conclusion findings

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Feasibility Study

On the basis of result of the initial study, feasibility study takes place.

The feasibility study is basically the test of its

Workability

Meeting user’s requirements Effective use of resources

Cost effectiveness

Decide whether or not to continue with the project?

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System Analysis

Study the existing system in detail is called analysis. During analysis, data are collected

Ways to study the existing system

1. Interview users of the current system

2. Read any manual or instructions which are in use 3. Observe the current system in operation

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System Design

Based on the user requirements and the detailed analysis of a new system, the new system must be designed. This is the phase of system designing.

It is a most difficult phase in the development of a system.

Normally, the design proceeds in two stages :

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Preliminary or general design:

1. The features of the new system are specified.

2. The costs of implementing these features and the benefits to be derived are estimated.

Structure or detailed design:

1. At this stage, the design of the system becomes more structured.

2. Input, output and processing specifications are drawn up in detail.

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Designing

1. Data capture forms 2. Type of user interface

3. Validations methods-how is input data going to be test?

4. Programs-if some new programs has to be written then they have to be designed at this stage

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Coding/Construction

1. After designing the new system, the whole system is required to be converted into computer understanding language.

2. This is also called the programming phase in which the programmer converts the program specifications into computer instructions, which we refer as programs. The programs coordinate the data movements and control the entire process in a system.

3. User documentation is prepared

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Testing

1. Before actually implementing the new system into operations, a test run of the system is done removing all the bugs, if any.

2. It is an important phase of a successful system.

3. After codifying the whole programs of the system, a test plan should be developed and run on a given set of test data.

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Testing

1. Unit Testing

2. Integration Testing

3. System testing. Test data is designed and the results are forecast

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Component Testing

Searches for defects and verifies the functioning of software components (modules, programs, objects, classes etc) that are separately testable.

Integration Testing

Tests interfaces between components, interactions to different parts of a system such as OS, file system and hardware.

System Testing

Concerned with the behavior of the whole system/product.

Acceptance Testing

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Implementation

1. After having the user acceptance of the new system developed, the implementation phase begins.

2. Implementation is the stage of a project during which theory is turned into practice.

3. During this phase, all the programs of the system are loaded onto the user's computer. After loading the system, training of the users starts.

4. File conversion

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Implementation

Main topics of such type of training are:

1. How to execute the package 2. How to enter the data

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After the users are trained about the computerized system, manual working has to shift from manual to computerized working. The following two strategies are followed for running the system:

Direct Change Over:

The old/existing system is immediately removed and the new system come into place

Parallel Run:

In such run for a certain defined period, both the systems i.e. computerized and manual are executed in parallel. This strategy is helpful because of the following:

1. Manual results can be compared with the results of the computerized system.

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Phased/Pilot Run:

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Maintenance

1. Maintenance is necessary to eliminate errors in the

system during its working life and to tune the system

to any variations in its working environment.

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System Maintenance and Review

The review of the system is done for:

1. Knowing the full capabilities of the system

2. Knowing/upgrade the required changes or the

additional requirements

3. Studying the performance

4. Keep watching on the new system

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What is Testing?

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What is Testing?

The process consisting of all life cycle activities, both static and dynamic, concerned with planning, preparation and evaluation of software products and related work products to determine that they satisfy specified requirements, to demonstrate that they are fit for purpose and to detect defects.

The process of detecting defects is called testing.

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Software Testing

The process consisting of all life cycle activities, both

static

and

dynamic

, concerned with

planning

,

preparation

and

evaluation of software products and

related work products

to

determine that they satisfy

specified requirements

, to

demonstrate that they are fit

for purpose

and to

detect defects

.

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What is Testing?

Dynamic

Executing the software code to demonstrate the

results (Chapter 4)

Static

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What is Testing?

Planning

What we want to do? Report on testing progress, status of the software under test, finalize and close testing when a phase completes. (Chapter 5)

Preparation

We need to choose what testing we’ll do? (Chapter 4)

Evaluation

Executing the test, we must check the results, evaluate the software and completion criteria

Software products and related work products

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What is Testing?

Determine that software products satisfy requirements

Checking products against the requirements.

Demonstrate software products fit for purpose

Software does enough to help the users to carry out their tasks. Software does what the user might expected.

Detect Defects

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Software Test and Driving Test Compared

Activities Driving Test Software Test

Planning and Preparation

Static and Dynamic

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Determine that they satisfy specified

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Planning and Preparation

1-Which routes to be followed? 2-Time duration

3-Questions to be asked

1-Checking testing progress

2-Status of the software under test

3-Finalize testing when phase completes

4-What testing we will do?

Static and Dynamic

1-Questions to the driver 2-Driving the car

1-Review the software 2-Executing the software

Evaluation

1-Questions 2-Written test

3-Observation during driving

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Determine that they satisfy specified requiremen ts 1-Checking patience 2-Checking confidence 3-Checking following the rules

4-Checking staring, clutch, gears are properly used by the driver

1-Review the code to check design

2-Review the design to check specifications

Demonstrat e that they are fit for purpose

1-Driver is able to drive 1-Software is fit for purpose

Detect defects

1-Finding faults of driver 2-Suggest improvements

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When we can meet our test objectives?

Testing Principle-Early Testing

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When we can meet our test objectives?

Testing Activities

1. Acceptance testing 2. Alpha testing

3. Beta testing or field testing 4. Component or unit or module 5. Integration testing

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Focusing on defects can help us plan our tests

Testing Principle- Defect Clustering

A small number of modules contain most of the defects discovered during testing.

Reasons of defect clustering

1-Code is complex 2-Code is tricky

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Solution to minimize clustering

1. Reviewing every module to find defects and failures

2. Early testing should be implemented on time

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The defect clusters change over time

Find more defects as the testing

improves and then as the defect prevention kicks in, defects

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Debugging removes defects

Debugging

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Debugging Removes Defects

Testing Principle-Pesticide Paradox

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Is the software defects free?

Testing Principle- Testing shows presence of

defects

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If we don’t find defects does that mean the user

will accept the software?

Testing Principle- Absence of errors fallacy

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Testing Principles-SUMMARY

1-

Testing shows presence of defects

2- Exhaustive testing is impossible

3- Early testing

4- Defect clustering

5- Pesticide Paradox

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The Psychology of Testing

Independent testing- Who is a tester?

Independence

Separation of responsibilities, which encourages the accomplishment of objective testing.

Level of Independence

Tests by the person who wrote the item under test Tests by another person within the same team such as

another programmer

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The Psychology of Testing

Reviewing and testing Principles

1. Communicate findings on the product in a neutral, fact-focused way without criticizing the person who created it.