What is "All Singles"?

“All Singles” is a method that tests several variables/arguments together. This method tests all permutation (all options). In order to know all the options we will use the Cartesian product algorithm, which is the easy way (in my opinion) to calculate all the possible options of several variables together.

The idea behind this method is that every value of each variable must appear in at least one test.

How to calculate the “All Singles”?

Let A1, A2, A3 be 3 variables/fields/parameters. 

• A1 has 1, 2, and 3 as values
• A2 has s, t for values
• A3 has y, z for values

The Cartesian equation will be: A1 X A2 X A3 Which means: {1, 2, 3} X {s, t} X {y, z}
In other words: A1 X A2 X A3 = {1, 2, 3} X {s, t} X {y, z}.

The number of test cases will be: 3X2X2 = 12 because we have 3 values for variable A1, 2 values for variable A2 and 2 values for variable A3.

Let’s start to write all the options (The red marked values are the choosen values):

Test Case #	Values Participates	Result
1	{1, 2, 3}X{s, t}X{y, z}	(1, s, y)
2	{1, 2, 3}X{s, t}X{y, z}	(1, s, z)
3	{1, 2, 3}X{s, t}X{y, z}	(1, t, y)
4	{1, 2, 3}X{s, t}X{y, z}	(1, t, z)
5	{1, 2, 3}X{s, t}X{y, z}	(2, s, y)
6	{1, 2, 3}X{s, t}X{y, z}	(2, s, z)
7	{1, 2, 3}X{s, t}X{y, z}	(2, t, y)
8	{1, 2, 3}X{s, t}X{y, z}	(2, t, z)
9	{1, 2, 3}X{s, t}X{y, z}	(3, s, y)
10	{1, 2, 3}X{s, t}X{y, z}	(3, s, z)
11	{1, 2, 3}X{s, t}X{y, z}	(3, t, y)
12	{1, 2, 3}X{s, t}X{y, z}	(3, t, z)

 

When to use "All Singles"?

• When the system is safety-critical or mission critical software (army and medicine applications).
• When we have few tests and we can do it in order to produce a higher quality product.

However, in cases you have many test cases; it recommended that you will use methods to decrease the number of test cases.

Practice 1

You have a system that should work on windows 2000, windows xp, internet explorer 6.5, internet explorer 7, .Net 2.0, and .Net 3.0. How many test cases can you perform using ‘all singles’?

Try to solve it before continue reading.

Practice 1 - answer

Let us mark:

• A = {win 2000, win xp}
• B = {IE 6.5, IE 7}
• C = {.Net 2.0, .Net 3.0}

Total test cases = 2X2X2 = 8

So, all options table will be:

Test Case #	A	B	C
1	Win 2000	IE 6.5	.Net 2.0
2	Win 2000	IE 6.5	.Net 3.0
3	Win 2000	IE 7.0	.net 2.0
4	Win 2000	IE 7.0	.Net 3.0
5	Win XP	IE 6.5	.Net 2.0
6	Win XP	IE 6.5	.Net 3.0
7	Win XP	IE 7.0	.Net 2.0
8	Win XP	IE 7.0	.Net 3.0

 

Practice 2

You have a screen with 3 combo boxes: Name (Keren, Dan, Andy, Max), Gender (Male, Female) and Job Title (IT, Programmer, QA, C.I.O). How many test cases can you perform using ‘all singles’?

Try to solve it before continue reading.

Practice 2 - answer

Let us mark:

• A = {Keren, Dan, Andy, Max}
• B = {Male, Female}
• C = {IT, Programmer, QA, C.I.O}

Total test cases = 4X2X4 = 32

So, all options table will be:

Test Case #	A	B	C
1	Keren	Male	IT
2	Keren	Male	Programmer
3	Keren	Male	QA
4	Keren	Male	C.I.O
5	Keren	Female	IT
6	Keren	Female	Programmer
7	Keren	Female	QA
8	Keren	Female	C.I.O
9	Dan	Male	IT
10	Dan	Male	Programmer
11	Dan	Male	QA
12	Dan	Male	C.I.O
13	Dan	Female	IT
14	Dan	Female	Programmer
15	Dan	Female	QA
16	Dan	Female	C.I.O
17	Andy	Male	IT
18	Andy	Male	Programmer
19	Andy	Male	QA
20	Andy	Male	C.I.O
21	Andy	Female	IT
22	Andy	Female	Programmer
23	Andy	Female	QA
24	Andy	Female	C.I.O
25	Max	Male	IT
26	Max	Male	Programmer
27	Max	Male	QA
28	Max	Male	C.I.O
29	Max	Female	IT
30	Max	Female	Programmer
31	Max	Female	QA
32	Max	Female	C.I.O

 

 The "All Singles" problem

If we have 3 variables:

• A1 with 10 values
• A2 with 5 values
• A3 with 4 values

The number of test cases will be: 10X5X4 = 200. We need to reduce the amount of test cases in order to be able to test a program in a normal amount of time.

We already learned "Boundary Values Testing" and "Equivalence Class Partitioning" methods that can help us reduce test cases. In few more minutes you will learn a method that can help us to solve the "All Singles" problem that called "All Pairs".

Summary

We as testers always need to know how much tests we need to perform or write on a requirement. We need to calculate the number of tests cases that can be done before we start to write the first sentence of the first test case. Only after knowing how much test cases can be done, we need to think if we need to reduce those test cases and how to reduce them.

We saw some black box methods than can help us reduce the amount of test cases and we will see some more methods that can help us. Sometimes, we can reduce the amount of test cases using our knowledge in the tested system and sometimes we can reduce test cases using our head and common sense.

We need to remember that we usually don't have enough time, money and manpower to test everything, so we need to reduce our test efforts in a smart way such that still find most of the critical and high priority bugs with minimum testing efforts.