Test document review and defect management are required during the test phase, which not only improves test efficiency, but also allows project managers to balance product quality, project schedule and cost based on defect convergence trends. When designing test cases, you need to pay attention to the design of reverse test cases and reliability test cases, which will more effectively find hidden defects in the product and improve product quality.
0 Preface
Online analytical instrument, also known as process analytical instrument, refers to a type of instrument that is directly installed in the process flow and performs automatic continuous analysis of the composition or physical parameters of the measured medium. In order to expand the market for online analytical instruments, some companies have begun to develop or improve the corresponding online analytical instrument products.
If the newly developed or improved analytical instrument can be operated on the user's site for a long time and reliably, in addition to the previous technical pre-research, design development and technical review, it is necessary to pass the product test on the product's function, performance and reliability. Verification in other aspects to ensure product quality. At present, the problems exposed by online analytical instruments at the user site mainly focus on software bugs, device failures, EMC problems, and measurement effects due to ambient temperature. According to the Pareto principle, not all defects in the product can be found in the test. However, some of the problems, such as software bugs and measurement environmental impacts, can be found and improved through intensive testing during the testing phase. This requires not only strengthening the quality awareness of testers, but also deepening the tester's understanding of test theory knowledge. And mastery of testing techniques.
1 Test basic theory
1.1 Test responsibilities
The role of the online analytical instrument tester can be divided into software testers, hardware testers, product testers, reliability testers, and certification testers, depending on the type of product module in charge. Software testers are mainly responsible for software black box testing. Hardware testers are mainly responsible for hardware unit testing and hardware and software integration testing. The reliability tester is responsible for the test of product reliability, mainly including environmental test and life test. The certification tester is mainly responsible for the test of the type test related to the CMC certification and explosion-proof certification of the product. Product testers' main responsibilities are to assist with unit testing and integration testing, perform system testing, compliance testing, and user testing to assist in analyzing and resolving testing issues. Of course, the organizational structure of different companies will be different, and the division of testers' responsibilities will be different. At present, most of the analytical instrument company software testing, hardware testing and reliability testing are mainly done by product testers.
1.2 Test definition
Glenford J. Myers provides a basic explanation of the definition and testing principles of testing in both The Psychology and Economics in The Art of Software TesTIng, in which the test refers to the process of executing a program to discover errors. .
At present, different people describe their definitions slightly differently. In 1993, the software engineering standard terminology proposed by the IEEE defined software testing as the process of using a manual or automated means to operate or evaluate a system or system component. The purpose was to verify that it met the specified requirements or to clarify The difference between expected and actual results. Although different people have different test definitions, different definitions clarify that testing should be a process that targets defects.
1.3 Test purposes
The purpose of the test is not only to discover product defects, but also to help the project manager improve some of the problems in the current development process by analyzing the defect distribution characteristics and the causes of the defects. At the same time, defect analysis can also help us design targeted test cases and improve test effectiveness. The ideal goal of the test is to achieve "zero defects in the product". Even if no defects are found during the test, the test of the process is meaningful. The complete test is an effective means to evaluate the quality of the product.
1.4 defect convergence
The theoretical research on defect management started late and the development is far from mature. Refer to the CMM5 definition specification and the current online analytical instrument industry characteristics, and classify product defects into four levels according to their severity: fatal, serious, general and recommended.
By testing the trend of defect convergence, it can reflect the quality change of the tested product, which can not only assist the project manager to make decisions, but also can be used as an important reference for product release. The test defect convergence evaluation example is shown in Figure 1. Online analytical instrument Test defect convergence can be evaluated in the following three aspects.
1) The cumulative number of defects found;
2) The number of defects submitted at each stage;
3) The number of defects left.
The cumulative number of test defects found to be stable and the number of defect submissions at each stage approached zero, indicating that the product quality is relatively stable, but does not mean that the product quality is good. When the defect residual trend curve falls, it indicates that the product quality has improved, and the defect residual trend curve gradually rises, indicating that the product quality continues to deteriorate. The convergence trend curve of the defect residual number is closer to 0, and the product quality is better.
2 test methods
According to the tester's understanding of the measured object, the test case design method can be divided into white box test and black box test.
White box test: Also known as structure test or logic drive test, you must know the internal working process of the software or product, and test it to check whether its internal operation is in accordance with the requirements and design. Test cases can be selected by means of logical coverage, path coverage, etc., and test coverage can be evaluated using test coverage. Online analytical instruments generally use a white-box test method for software testing and hardware testing during the unit testing phase, mainly to verify whether the software flow, software algorithms meet the requirements and whether the hardware signal link is correct.
Black box testing: Also known as data-driven testing or functional testing, it is tested against the functional requirements of the software or product. Tests are performed to check whether each function meets the requirements, regardless of its internal logical structure. The following describes several black box testing methods commonly used in online analytical instrument testing.
2.1 Equivalence class division
The functional test related technology that testers should first understand and master is the equivalence class division. It is important to understand the usage of this technology because it is the basis of many other software testing techniques and approaches. An equivalence class is a collection of input fields in which each input condition is equivalent. If one of the input conditions cannot find a product or software defect, then the other input conditions in the collection will not be tested. Found a defect. The equivalence class is divided into a valid equivalence class and an invalid equivalence class. The effective equivalence class is a collection of meaningful input data that is meaningful to the product specification; the invalid equivalence class is an unreasonable specification of the product. A collection of input data that is meaningless or meaningless. When designing a test case, you need to consider both equivalence classes.
2.2 Boundary value analysis
From the long-term test work experience, a large number of faults often occur on the boundary of the input domain or the output value domain, rather than inside it. To design a test case using the boundary value analysis method, first determine the boundary condition, and enter the boundary between the equivalence class and the output equivalence class, which is the boundary condition that should be emphasized. The basic idea of ​​the boundary value analysis method is to select the value that is exactly equal to, just less than or just greater than the boundary as the test data, instead of selecting the typical value or any value in the equivalence class as the test data. During the test, test cases that considered boundary conditions have higher test yields than other test cases that do not consider boundary conditions.
2.3 Causal graph method
The test method of equivalence class division and boundary value analysis mainly considers a single input condition, but does not consider the mutual constraint relationship between the various input conditions, and does not consider various combinations of input conditions. If one considers a test method that is suitable for describing a plurality of input conditions and produces a plurality of corresponding actions, a causal map can be used, and the causal graph method is applicable to a combination of a plurality of conditions and correspondingly generating a plurality of results. In more complex cases, this test method can effectively help us check the output of multiple combinations of conditions and design efficient, non-redundant test cases.
2.4 Error guessing
Error guessing method, based on experience and intuition to speculate on various errors that may exist in the product, so as to design a test case method in a targeted manner. The basic idea of ​​the error guessing method is to guess all possible errors in the product and special cases that are prone to errors based on past work experience, and select test methods and design test cases according to them.
Of course, there are other test methods that can be used in test case design, such as orthogonal design, special value method, process analysis method, and combined design method. Each test method has its own strengths. It should be based on the specific needs of the product, select the appropriate test method, design efficient test cases, and effectively expose the hidden defects in the product.
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