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# Thread: Assistance with Boundary value Testing

1. ## Assistance with Boundary value Testing

I was going through some questions from ISTQB sample questions and had a problem with one of them and i need an advice and assistance from testing experts here.

the questions is
An input field takes the year of birth between 1900 and 2004
The boundary values for testing this field are
a. 0,1900,2004,2005
b. 1900, 2004
c. 1899,1900,2004,2005
d. 1899, 1900, 1901,2003,2004,2005

I am thinking the answer should be D as we need to test with values within the specified limit, some values outside the limit and both the values specified. In my initial training for software traning i was thought a formula for getting the values for this testing - If M and N are the values then test should be performed with the values M, N, M+1, N+1, M-1, N-1. Considering this I came to a conclusion that D is correct and the key for this sample paper says that option C is correct and i am bit confused with this answer.

I will be grateful if you guys can assist me in confirming the correct answer.

2. ## Re: Assistance with Boundary value Testing

I looked this up in a couple of text books, but I'm still not 100% sure what the answer is...

"Software Testing An ISEB Foundation" says that for boundary value analysis use the boundary and one value either side as close as you can get.

The example it gives is integers with valid range 1 to 99. The answer it gives for this is 0,1,2,98,99,100.

"The Testing Practitioner" says that for boundary testing you test each boundary with "a minimum of two test cases, or three for full boundary value analysis".

The example it gives is testing "IF 23 &lt;= age &lt; 44 THEN". The answers for this are:

[ QUOTE ]
The boundary values to be selected, when taking the minimum of only two boundary test cases, for age are: 22(invalid), 23(valid), 43(valid) and 44(invalid).

[/ QUOTE ]

and

[ QUOTE ]
For full boundary value analysis three values per boundary are selected
...
For the lower boundary the boundary test cases would be 22 (invalid), 23 (valid), 24 (valid). The added boundary value test case will find an additional defect when for example "age=23" has been implemented
...
For the upper boundary the boundary values test cases are 43 (valid), 44 (invalid) and 45 (invalid).

[/ QUOTE ]

So the answer could be C or D, it's an ambiguous question.

3. ## Re: Assistance with Boundary value Testing

Gotta love multiple-choice tests.

Even better are the thousands of "sample questions" sites that indicate the "correct" answer, without any explanation.

It must certainly make for a fulfilling learning experience.

4. ## Re: Assistance with Boundary value Testing

I was taught the same. i.e.:If M and N are the values then test should be performed with the values M, N, M+1, N+1, M-1, N-1. Sometimes even checking in between to verify.

5. ## Re: Assistance with Boundary value Testing

My question for everyone is,
How will you perform boundary value analysis for font size of 1 and 1638.

6. ## Re: Assistance with Boundary value Testing

Hi CamLee,

here is my A-to-E approach:

A. First, we test the lower boundary of the class (if the lower boundary exists).
B. Second, we test the upper boundary of the class (if the upper boundary exists).
C. Third, we test any value inside the class (if the class consists of 3 or more values).
D. Fourth, we test the upper boundary of the class that precedes the tested class (if the preceding class exists).
E. Finally, we test the lower boundary of the class that follows the tested class (if the following class exists)

Our lower boundary is 1900 and our upper boundary is 2004.

Let's apply A-to-E approach:

A. 1900
B. 2004
C. 2003 (basically any year from 1901 to 2003 inclusively)
D. 1899
E. 2005

IMHO, correct answer is d., because in case of c. we don't test values inside the class (step C. of A-to-E technique). In case of d. we do have redundancy: there are 2 inputs for testing inside the class instead of 1 (1901 and 2003 – either one is good), but it's better to have 1 extra input that miss important input like it happened in case of answer c.

http://www.qatutor.com/7_4.html (Scroll down to section EQUIVALENT CLASSES)

Thank you,
Roman

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