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 ） aman@ehime-u.ac.jp (C) 2007-2022 Hirohisa AMAN 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 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 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 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 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 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 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 black box reuse  Library form For example, using existing functions as it is, (example) C.in language scanf function or printf function #include existing code (C) 2007-2022 Hirohisa AMAN New code 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 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 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 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