The research of V model in testing embedded software Liu, Shuping1 Pang,Ling2

1 North China Electric Power University, 2 North China Electric Power Universityhdlsp@163.com

Abstract

Software testing is an important link of software quality guarantee, regarding to the embedded software testing that is much more compelxed, needing a clear stage development test model that better controlled. The article discussed the model that already existed, further excavates the parallelism between test stages, trys to proposes a improved V model, This model make the software testing pass through the each stage of software development cycle , That can discover software mistakes as early as possible .simultaneously unify the actual small software development project— GPRS extender board correspondence experiment , has proven the accuracy and the validity of this model .

1 Introduction Along with the development of embedded

technology, the embedded application unceasing growing as well as the embedded system complexity unceasingly to enhance ,requiring the scale and the complexity of embedded software also unceasingly enhanced, the embedded software quality and the development cycle have decisive influence on the product final quality ,thus the embedded software testing became the research hotspot.

Because of the particularity of the embedded software , the embedded software testing stretch across the software and hardware, needs to deal with the software issue, the hardware breakdown as well as the software and hardware coordinated questions, causes to the embedded software testing relative difficulty, It’s very difficult to form one test plan to suit all concrete tests case . But, we may excavate some general characters of embedded software, forming the relatively general model.

pang1982ling@sina.com V model has provided the development test

model which the stage were clearly controlled. But in view of the present the embedded software system more and more complex as well as software and a hardware closer union day by day , V model also exposed many flaws and insufficiency. Therefore making the improvement of V model and union actual development software to validate it.

2 The integral plan of embedded software testing 2.1 V model of software test technology

The value of V model is marking the different rank extremely explicitly which existed in the test process , and clearly described the corresponding relations between these test ranks and the stages of development process. V model deficiency:

(1) The V model is unable to guide the the entire process of project . A model must be able to process all the aspects of development , a model and an independent project plan should have difference. The model should not describe each project concrete detail, should carry on the instruction of the project.

(2) According to V model, software test execution after the code realization , It’s easy to cause finding errors until the final acceptance test which the hided in demand stage ,so it cost a lot to discover and solve these errors.

(3)V model divides the system development and the test process into different stages having the solid boundary, It’s very difficult for people to stride these boundaries to gather the information which the test needs. Moreover, it also hindered synthesizing the information that obtained from the different stages.

International Conference on Computer Science and Information Technology 2008

978-0-7695-3308-7/08 $25.00 © 2008 IEEE

DOI 10.1109/ICCSIT.2008.51

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International Conference on Computer Science and Information Technology 2008

978-0-7695-3308-7/08 $25.00 © 2008 IEEE

DOI 10.1109/ICCSIT.2008.51

463

(4) V model is easy to let the person form the misunderstanding "the test is a stage after development ", "the test object is the programme " and so on.

2 The improved V model Regardless of the traditional software

acceptance test, or facing the software test of entire development process , the test object which it aims at all is the software product, the half-finished product or the process work product, its reported test result is also only for distinguish the flaw that was found in the product at present stage, and correct them to support the next stage development work. In the aspect of long-term develops of the software development, merely achieves these is insufficient.

The software test as the important way of guarantee the software quality , not only must be able to distinguish the software product flaw and performs correct, but also should unify the technical method in the software test, produces the measure of software development process, thus support the appraisal and improvement of organization to software development process.

The XP(extreme programming) thought considered that, The test must be advance, the test should pass through the entire development process. At the same time, the test price analysis also tells us: The test is the more early the better. Based on this, we considered this in the improved V model, will introduce the test to development process, including requirements analysis stage, outline design and detailed design stage.

This article has made the improvement in view of some traditional V model flaws, the figure 1 shows:

Figure 1 This model has mainly made the

improvement to the following aspects: (1) carries on the test design before the test Regarding the test design, V model user often treat the test and test design separatly, after the preparation of development documents to be ready, may start to carry on the correlative test design.

Like the figure 1 shows, the corresponding test design cover above the related development process. (2) each test stage overlapping

To V model improvement, excavates each stage parallelism, in revision model, each stage of development process execute according to the former model order , and simultaneously carries on the corresponding test design .Regarding these test stage which original execute strictly according to order , we allow it’s flexible to do suitable ahead of time and retard, making neighboring, even between the non- neighboring stages can appear partially overlaps, thus permits the concurrent execution. (3) nimble return test

The return test as a composition of software life cycle , holds the very big proportion work

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load in the entire software testing process, each software development stage can carry on return test many times.

(4) carries on the test to each delivered product

Each delivered product in thedevelopment process, once finish thedevelopment,must carry on the test through the suitable way. In the performance history each may pay product, once the conclusion development, all must carries on the demand test in particular. Especially the demand analysis test. Therefore this article the improved V model introduces the demand analysis test firstly.

(5)Emphasized the importance of acceptance test

Emphasized the importance of acceptance test and establish the approval standard before accepts the delivered system.The approval standard not merely defines thedemand,but also should be defined before test, this will help to point whether some demands correct, as well as whethersome is neglected.

Acceptance test: Whether the examination product conforms final user's demand, and guarantees the system workable and useable before deliver to user. The user needs to use the acceptance standard to validate the system

Above points are the improvements which this article in view of traditional V model flaws and the union with the present embedded software particularity.

3 Example analysis The practice part is the hardware platform

and uC/OS-II operating system environment based on the UP-NETARM3000, the realization of GPRS extender board correspondence function .

The developing software is the expansion of function module to the embedded system experimentation platform.Realizing the basic function that send fixed messages, meets and receive the phone and so on. Using the keyboard of the development platform and the crystal

screen to realize man-machine interactive. In this project test, the questions which faces

are: (1)program to realize the new added function

module; (2)the original function module needs to

design thoroughly the test case; (3)the test personnel and the test time are all

unable to increase. 3.1 Test environment establishment Hardware: ARM embedded development platform, JTAG simulator using in the ARM7TDMI , above PC machine Pentimu100.

Software: PC machine operating system WinXP, ARM SDT2.51 or ADS1.2 integrated development environment,simulator driver,super terminal communication procedure. 3.2 Test designs and execution

After the expansion function development cycle starts, according to the new added function design each test case, when the development process is at the code stage, execute unit test and the integration test case, and gradually starts the function test. After all new functions code completion of work probably 3/4, starts to carry out the original system test case.After the code finished, starts the large-scale execution of new design system test case, And carries on the test case design and the execution to the function module .

Using test model which this article proposed, has completed formerly 1.5 time of tests tasks in the scheduled time, after the code stage error ratio is lower than the error ratio in code period , the mistakes discovered in code period are much more than the period of code finished. In other words, majority of errors are discovered in the code stage promptly. 3.3 Merits

1.the test activity started from the test stage to involve, enhanced the problems discovery rate; Realizing that discovered early as far as possible , early revises, few harms.

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2.management flows are standard, from designs to realize and to the execution, can follow the certain plan;

3.using the parallel development greatly reduce the development test time.

4 Test driven development The test driven development is an important

constituent of extreme programming, Its basic thought is compiling the test code firstly before the development of function code.In other words, after clearing about must develop which function, first pondering how to carry on the test to this function, and finish the test code compilation, then compile the related code to satisfies these test case. Then increases other functions circulated,

until finish the entire function development. The clean code that works is thegoal which theTDD pursues.

The test driven development has many merits:

(1) finishes when the work should finish. Indicated that the development personnel may very clear see this section of work had already finished, but the traditional way is very difficult to know when the code ended.

(2)understanding the code and use code comprehensively and correctly but traditional way does’t have this opportunity.

(3)reduce the exchange cost between the developed group, enhanced the mutually trusted degree.

(4) avoided the transition design. (5)because the compilation tests and

compiles the code is the same programmer, That can reduce the cost which the understanding code spends.

(6)discovers more bugs compared to the traditional test ways.

5 Summaries and the next step of work

Along with the deep understanding of people to the software test process , understanding each test stage unceasingly

deepens, the software test process management model has the evolution unceasingly , the most representative is the V model, this article first carries on the discussion to V model, then proposed a improved V model in view of the time structure and the return test time scope , and has proven this model accuracy and the validity through the example analysis. Using this test model to be allowed discovered the mistakes as soon as possible , reduced the software product development cycle, further improved the software quality.

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testing”;

[2] Willian E Lewis. Software Testing and Continuous

Quality Improvement .Florida CRC Press,2000:41-45;

[3]James S Collofello,Zhen Yang,and John D Tvedt .

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IPCCC 96,1996:289-293;

[4]Zhu Yinfei,Brief analysis the requirements analysis

of software development project ,Journal of Nanjing

Radio＆TV University No4 ,2006:85-86;

[5]Chen Bingzi,The Improvement of Software Testing

Based on Requirements Change, Huazhong University

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[6]David Astels, Rin Jeffries,Test-Driven development

A Practical Guide, Chinese electric power publishing

company.

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