Software testing - how to select the appropriate orthogonal table

demand ：

There are multiple controls in the form （ typeface 、 Character style 、 Color 、 Font size ）,

Each control has multiple values

typeface ： Imitation song 、 Regular script 、 Chinese color cloud

Character style ： bold 、 Italics 、 Underline

Color ： Red 、 green 、 Blue

Font size ：20 Number 、30 Number 、40 Number

If you follow the normal steps , need 3*3*3*3=81 Combinations of , You need to write 81 Test cases , It seems more , In view of the large amount of this combination , How to use the least set of test cases to obtain the maximum test coverage , You can use   Orthogonal array method （--- Definition ： Orthogonal permutation method is to use the smallest set of test procedures to obtain the maximum test coverage . attach ： This is a research result of Statistics ）.

Category of orthogonal table

Can be divided into ： Single horizontal orthogonal table and Mixed level orthogonal table .

Single horizontal orthogonal table ： An orthogonal table with the same number of levels in each column is called an equal level orthogonal table . such as ：L9 (3**4) -->（ attach ： In parentheses, it means 3 Of 4 Power , The same below .）、L2 7(3**13) be called 3 Horizontal orthogonal array . L4 (2**3)、L8 （2**7） be called 2 Horizontal orthogonal array . A single horizontal orthogonal table can be used Ln(m**k) Express ,n It's the number of lines ,m Is the horizontal number ,k It's a factor . For example, the above requirement example ： It can be understood as 4 Factor （ typeface , Character style , Color , Font size ）,3 level （ It means that there are three options in each factor , such as ： In the font Imitation song 、 Regular script 、 Chinese color cloud 3 A choice ）. In general , We can directly determine m and k,n  The number of rows can be calculated according to the number of levels and factors , Formula for ：n=k*(m-1)+1.

Mixed level orthogonal table ： An orthogonal table with different horizontal numbers in each column is called a mixed horizontal orthogonal table . such as ：L8 （4**1    2**4）-->（ attach ： In parentheses, it means 4 Of 1 Power and 2 Of 4 Power . There are... In the table 8 That's ok , The level of one column is 4, Yes 4 The level of the column is 2.）. The mixed level orthogonal table can be used Ln(m1**k1    m2**k2) Express . In general , We can directly determine m and k,n  The number of rows can be calculated according to the number of levels and factors , Formula for ：n=k1*(m1-1)+k2*(m2-1)+k3*(m3-1)......+ kx*(mx-1) + 1.

View orthogonal table

http://support.sas.com/techsup/technote/ts723_Designs.txt

How to select an appropriate orthogonal table

If we are sure there is 3 Factor 2 level , Calculation n=3*(2-1)+1=4, It should be expressed as L4(2**3), So let's see if you have an orthogonal table that is exactly equal to this , If there is , Then copy the variable values into this table , without , Select... As follows ：

1. The number of levels is equal , When the factors are equal , The number of rows is just like that of a slightly larger custom orthogonal table

2. The number of levels is equal , When the factors are not equal , The number of rows is just like that of a slightly larger custom orthogonal table , The factor is just like a slightly larger custom orthogonal table . such as ： Customize to ：                 L7(3**3), We choose L9(3**4),  After application , Remove the last column of factors

3.   When the horizontal numbers are not equal , namely ： Mixed orthogonal array .

example ：

There are five factors （ Variable ）：

　　A、B、C、D and E

　　 Two factors have two levels （ Value of variable ）、 Two factors have three levels , A factor has six levels ：

　　A：A1、A2

　　B：B1、B2

　　C：C1、C2、C3

　　D：D1、D2、D3

　　E：E1、E2、E3、E4、E5、E6

Customize to ：L11(2^2 3^2 5^1)

Choose an orthogonal table ：

      The number of factors in the table （ Variable ）＞＝5

　　 The number of levels with at least two factors in the table （ Value of variable ）＞＝2

　　 The level of at least two other factors ＞＝3

　　 There is at least one other factor in the number of levels ＞＝6

　　 Take the least number of rows ：L49(7^8) perhaps L18(3^6 6^1)）

 result ：L18(3^6 6^1)

example ：

m1=5   k1=5

m2=2   k2=1

n=22

Customize to ：L22(5^5   2^1)

Nothing exactly equals 22 Orthogonal table of , Select greater than 22 And satisfy m>=max(m1=5, m2=2),   k>=k1+k2=6 Orthogonal table of , We found that

L25(5^6)、L49(7^8) All conform to , Select a small number of rows , namely ： Final choice  L25(5^6)

For mixed orthogonal tables , have access to allpairs Tools help us make choices .

allpairs Tool use ：

1） Make a value table （ No numbering ） Factors and levels （ The factor is one line .... ）

2） Copy the value table to a txt In the text （ Don't change the format ） user.txt

3） hold txt Text placement allpairs In the folder of the tool

4） Run in folder cmd （ I got to the bottom of this folder ）

4） stay allpairs Use under the folder path of the tool DOS command ：

allpairs.exe The establishment of a txt Text > Use case result text （ Can not exist ）

example ：