Shulou(Shulou.com)06/03 Report--

V model, W model, X model, H model

1. V model

In software testing, V model is the most widely known model, although many experienced testers are still not familiar with V model, or other models. The V model has existed for a long time and has some common characteristics with the waterfall development model, so it has been criticized and questioned as well as the waterfall model. The process in the V model, from left to right, describes the basic development process and testing behavior. The value of the V model is that it clearly indicates the different levels of the testing process, and clearly describes the corresponding relationship between these testing phases and the various stages of the development process. Limitations: testing as the last activity after coding, requirements analysis and other early errors can not be found until later acceptance tests.

1. From the perspective of horizontal correspondence

On the left is the design and analysis, which is the process of software design and implementation, accompanied by the quality assurance activity-- the process of audit, that is, the static testing process; the right is the verification of the results on the left, which is the process of dynamic testing, that is, testing the results of design and analysis to confirm whether the needs of users are met. Such as:

L requirements analysis and functional design correspond to acceptance tests, indicating that while doing requirements analysis and product functional design, testers can read and review the results of requirements analysis, so as to understand the design characteristics of the product, the real needs of users, determine test objectives, prepare use cases (Use Case) and plan testing activities.

When the system designer is designing the system, the tester can understand how the system is implemented and what platform it is based on, so that they can design the test scheme and test plan of the system, and prepare the test environment of the system in advance, including the purchase of hardware and third-party software. Because these preparations actually take a lot of time.

When the designer is doing the detailed design, the tester can participate in the design, review the design, find out the defects of the design, design the test cases in various aspects, such as functions and new features, and improve the test plan. and develop test scripts based on these test cases.

While programming, unit testing is a very effective way to find out the errors in the program as soon as possible. Sufficient unit testing can greatly improve the quality of the program and reduce the cost.

It can be seen from the V model that we can clearly see that the quality assurance activity and the project are carried out at the same time, and the software testing starts as soon as the project is started, which avoids the misunderstanding caused by the waterfall model-software testing is carried out after the code is completed.

2. From the vertical direction

The upper part of the horizontal dotted line shows that the main work of demand analysis, definition and acceptance testing is to face the user, to fully communicate with the user, or to complete it with the user. Most of the work in the lower part of the horizontal dotted line, relatively speaking, is technical work, carried out within the development organization, mainly by engineers and technicians.

From the vertical point of view, the more below, the more white-box testing methods are used. When it comes to integration and system testing, it is more likely to combine white-box testing methods with black-box testing methods to form gray-box testing methods. In the process of acceptance testing, because users generally have to participate, the black box testing method is used.

II. W model

The limitation of V model is that it does not clearly describe the early testing, and can not reflect the principle of "early and continuous software testing". Add tests that should be carried out synchronously at all stages of software development in the V model, and evolve into the W model (as shown in the following figure). It is not difficult to see in the model that development is "V" and testing is a parallel "V". Based on the principle of "early and continuous software testing", the testing activities in the software requirements and design phase should follow the principle of IEEE1012-1998 "Software Verification and validation".

W model is proposed by Evolutif company. Compared with V model, W model is more scientific. W model is the development of V model, which emphasizes that testing is accompanied by the whole software development cycle, and the object of testing is not only the program, but also the requirements, function and design. Testing and development are carried out at the same time, which helps to identify problems as soon as possible.

The W model also has its limitations. Both W model and V model regard software development as a series of serial activities such as requirements, design, coding and so on, which can not support iteration, spontaneity and change adjustment.

Third, X model

The X model is also an improvement of the V model. The X model proposes separate coding and testing for individual program fragments, and then through frequent handover, the executable program is finally integrated through integration.

The left side of the X model describes separate coding and testing for individual program fragments, after which frequent handover occurs and eventually becomes executable programs through integration, and then these executable programs are tested. The finished product that has passed the integration test can be encapsulated and submitted to the user as part of a larger scale and scope of integration. Multiple parallel curves indicate that changes can occur in various parts. As can be seen from the figure, the X model also locates exploratory testing, which is a special type of test that is not planned in advance, which often helps experienced testers find more software errors outside the test plan. However, this may cause a waste of manpower, material and financial resources to the testing, which requires a high level of proficiency of the testers.

4. H model

In the H model, the software testing process is completely independent, runs through the whole product cycle, and carries out concurrently with other processes. When a test point is ready, it can be carried out from the test preparation phase to the test execution phase. Software testing can be carried out as soon as possible, and can be carried out at different levels according to the different objects being tested.

This diagram demonstrates a test of "microcirculation" at some level throughout the production cycle. The other processes noted in the figure can be any development process, such as a design process or a coding process. In other words, as long as the test conditions are ripe and the test preparation activity is completed, the test execution activity can be carried out.

The H model reveals a principle: software testing is an independent process that runs through the whole life cycle of the product and is carried out concurrently with other processes. The H model points out that software testing should be prepared and executed as soon as possible. Different testing activities can be carried out in a certain order, but they can also be repeated. As long as a test reaches the ready point, the test execution activity can be carried out.

1. Software testing process model-V model is a variation of software development waterfall model, which mainly reflects the relationship between testing activities and analysis and design.

Limitations: early errors such as testing as the last activity after coding, requirements analysis, etc. can not be found until later acceptance tests.

two。 Software testing process Model-W Model

On the basis of V model, synchronous testing in thousands of development stages is added to form W model, and testing and development are carried out simultaneously to find problems as soon as possible.

Limitations: development activities are still regarded as serial activities from the beginning of requirements to the end of coding. Only after the completion of the previous phase can the next phase of activities be started. Iteration, spontaneity and change adjustment are not supported.

3. Software testing process Model-H Model

In the H model, software testing process activities are completely independent, run through the entire product cycle, and are carried out concurrently with other processes. When a test point is ready, it can be carried out from the test preparation phase to the test execution phase; software testing can be carried out as early as possible; software testing can be carried out at different levels according to the objects being tested.

Advantages of various models:

V model: emphasizes several test levels that need to be experienced in the development of the whole software project, and corresponds to each development level; the objects that ignore testing should not only include programs, and do not specify the testing of requirements and designs.

W model: supplements the neglected contents of V model, emphasizes the priority of test planning and the testing of system requirements and system design; like V model, there is no description of the process of software testing.

H model: emphasizes that the test is independent and can be executed as long as the test is ready.

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