What are the black box test case design methods in software testing methods?

​​​​​​ Software testing methods The big direction is Black box test method and White box test method .

So-called Black box test method , Just care about the function , Don't care about code implementation details .

So-called White box test method , Is concerned about the specific implementation of the code , Cover the code as much as possible .

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One 、 Division of equivalence class

Equivalence class partition is a typical black box test method .

The equivalence test method is to put all possible input data , That is, the input field of the program is divided into several parts , Then select a few representative data from each part as test cases . Using equivalence class partition method to design test cases needs to go through equivalence class partition （ List the equivalence classes ） And selecting test cases , It will not be exhaustive testing process for a reasonable classification , So as to ensure the integrity and representativeness of the designed test cases .

There are two different cases of equivalence division ： Effective equivalence class and invalid equivalence class .

1、 Effective equivalence class means that it is reasonable for the requirement specification of the program , A collection of meaningful input data . Using the effective equivalence class, we can check whether the program has achieved the function and performance specified in the specification （ Confirmation process ）.

2、 Invalid equivalence class （ In contrast to the definition of effective equivalence class ） It means that it is unreasonable for the requirements specification of the program , A collection of meaningless input data . Using the invalid equivalence class, we can test the exception handling ability of the program for invalid data （ Inspection process ）.

When designing test cases , We should consider these two equivalence classes at the same time . because , Software should not only be able to receive reasonable data , To be able to stand the test of accidents . This kind of testing can ensure that the software has higher reliability .

An example in the book is very easy to understand , For example, a file system requires that the monthly input information be 1990 year 1 month ~2049 year 12 month , And by the 6 Digit composition , front 4 A digit represents a year , after 2 Bit means month .

(1) Divide equivalence classes and number

Input equivalence class	Effective equivalence class	Invalid equivalence class
Type and length of date	(1) Yes 6 Four digit characters	(2) There are non numeric characters
		(3) Less than 6 Four digit characters
		(4) More than 6 Four digit characters
Year range	(5) Be situated between 1990~2049( With borders )	(6) Less than 1990
		(7) Greater than 2049
Month range	(8) Be situated between 01~12( With borders )	(9) be equal to 0
		(10) Greater than 12

(2) Design test cases , Cover all valid equivalent classes .

Test data	Expected results	The valid equivalent class of the cover
200211	The input is valid	(1)(5)(8)

(3) Design test cases , Override all invalid equivalent classes .

Test data	Expected results	Override invalid equivalent class
95June	Invalid input	(2)
20036	Invalid input	(3)
2001006	Invalid input	(4)
198912	Invalid input	(6)
205901	Invalid input	(7)
200100	Invalid input	(9)
200113	Invalid input	(10)

Two 、 Boundary value analysis

Boundary value analysis is a kind of black box test method to test the input or output boundary value . Generally, the boundary value analysis method is used as a supplement to the equivalence class division method , In this case , Its test case comes from the boundary of equivalence class .

Long term testing experience tells us that , A lot of errors occur at the boundary of the input or output range , Not inside the I / O range . Therefore, test cases are designed for various boundary conditions , We can find out more mistakes .

3、 ... and 、 Other common black box design use case methods

Decision table method

Cause and effect diagram

Orthogonal test method

State migration diagram method

Process analysis

Input field test method

Output domain analysis

Anomaly analysis

False suspicion