Softwaretesting 02 eng

ソフトウェアテスト
　　 [2] ソフトウェア工学の概の概概
要
Software Testing
[2] Overview of Software Engineering
あまん ひろひさ ひろひさ

阿萬 裕久 裕久（ AMAN

Hirohisa ）

(C) 2007-2022 Hirohisa AMAN

1


Role of software
 the computer system
Combination of hardware and software
computer system
software
hardware

master the hardware
is the role of software
how the hardware
It's up to the software to
make the most of it
Games are a typical example

(C) 2007-2022 Hirohisa AMAN

2


Software Liability Is Serious
 The key to safety and security in everyda
y life
Software reliability
 Software bugs can cause serious damage
 Possibility of impact on electricity, gas, water su
pply, transportation, and finance
(Example) Stock exchange stops → Major damage Major damage
 may cause accidents
(Example) Elevator malfunction → Major damage Personal injury injury

Needs to be tested for a variety of
situations (C) 2007-2022 Hirohisa AMAN
3


Software Features (1/4)
 It is difficult to grasp the actual situ
ation
 Software is logical, not physical
 in short, Does not actually exist as a “t
hing”

(C) 2007-2022 Hirohisa AMAN

4

Software Features (2/4)
 Work concentrated on the developme
nt process
 Hardware, the flow is to develop a produ
ct and manufacture it in a factory.
 For software, manufacturing is just a cop
ying
 Quality and cost are centered on the dev
elopment process
"Everything is defective from the beginning" → Major damage
　 It is all about not failing in development
(C) 2007-2022 Hirohisa AMAN

5


Software Features (3/4)
 Long period of operation and mainten
ance
Rather than the time it took to create, the s
oftware
 operation(actually used by users)
 Maintenance(Modify, improve, and exten
d functions)
The period of doing is much longer
Ease of maintenance is the
key
(C) 2007-2022 Hirohisa AMAN

6


Software Features (4/4)
 low reuse
 Hardware: It is common to reuse existin
g parts
 Software: It is difficult to complete just b
y combining parts (requires a lot of custo
mization)
 There is software that can be reused in t
he form of libraries, but it cannot be use
d without programming.
(C) 2007-2022 Hirohisa AMAN

7


Reuse
 There are two types of software reuse
 Black Box
No need to worry about the contents, use it
like a part
 White Box
Copy and paste the program and rewrite it
as needed

(C) 2007-2022 Hirohisa AMAN

8


black box reuse
 Library form
For example, using existing functions as it is,
(example)
C.in language
scanf function or
printf function

#include <xxxx.h>

existing
code

(C) 2007-2022 Hirohisa AMAN

New
code

9


white box reuse
 “Copy and paste" the source code
For example, using part of existing source code.
Transcribe codes from books and web pages
There is also a risk of copying mistakes (bugs) a
nd misusing it.

Example: Even if you copy and paste a program that
you do not understand, you will only get confused.

existing
code

copy

(C) 2007-2022 Hirohisa AMAN

New
code

10


[Exercise 1]
Consider the code clone problem
 Copy and paste the source code as it i
s, or change part of it and use it as "c
ode cl injuryone”
 In the software industry, software wit
h many code clones is regarded as a
problem
Why?

(C) 2007-2022 Hirohisa AMAN

11

What is good software
 Note that the concept differs dependi
ng on the viewpoint
user
friendly

Understanding/Maintenance
It's easy to do

Good
software

the required
specifications
A user
meets
or

Development
cost/
Appropriate Developer
period

client
Software engineering is mainl injuryy from the devel injuryoper's perspect
(C) 2007-2022 Hirohisa AMAN

12

User's Perspective (1)

Satisfaction of required specifications
Requirements can be broadly divided i
nto two types:
 Functional specifications: 　 Functions to b
e achieved
Example: User authentication
 Non-functional specification: "How" should
the requirements be realized
Example: Authentication for 500 users must
be completed within 3 seconds
(C) 2007-2022 Hirohisa AMAN

13


User's Perspective (2) Operabili
ty
 In a word, "ease of use”
 Easy to operate
 Easy to understand operation
 Indirectly, operating speed and memory
usage are also related.
(I don't want to use so-called "heavy" syste
ms)

(C) 2007-2022 Hirohisa AMAN

14


Developer's Perspective (1) Cos
t and Period
 Low development cost is desirable
 The development period is within the
deadline (until delivery) to
 It is rare to be able to develop slowly ov
er time
 Need to finish on time with limited resou
rces and time
It can be developed at low cost and delivered within
the deadline, and The goal is to develop software that
satisfies the required specifications.
(C) 2007-2022 Hirohisa AMAN

15


Developer's Perspective (2) Mai
ntainability
 Once completed and put into operation, t
he required specifications almost always
change.
 "I want you to change this way"
 Request for addition or expansion of function
s "More such functions"

 Bugs may be found

Software that is easy to maintain is “good” software & “Ease of
understanding” is also important because it may be maintained by
another person
(C) 2007-2022 Hirohisa AMAN

16


Three characters that appear in s
oftware development sites
 QCD
 Quality (Quality)
 Cost (Cost)
 Deadline (Delivery)

 KKD
 intuition
 experience
 courage

important in the
manufacturing
industrynameans
three pillars

It means a site that
is not well
managed

(C) 2007-2022 Hirohisa AMAN

17


Classification of software
 Basic software
What users
 Application software
want
 middleware
Application
software
middleware
 embedded software
An image of these three layer Basic software
s embedded in hardware

on the calculator
What we can offer

(C) 2007-2022 Hirohisa AMAN

18


[Exercise 2]List the chal injuryl injuryenges in devel injury
oping and maintaining embedded soft
ware.
 Thinking about embedded software fo
r elevator control

 When developing this software, what
is more difficult than general softwar
e?
 Also, what about maintenance?

(C) 2007-2022 Hirohisa AMAN

19


life cycle
 life cycle: The Life of Software
development (development)
plan
Requirements analysis
external design
internal design
implementation
normally
(programming)

test

Here is
the longest

Operation/maintenance
(C) 2007-2022 Hirohisa AMAN

waste

20