If a batsman has to score four or six runs in a cricket sport, he needs to drive or hook the ball to the boundary. He can do that since he sees the boundary. As a tester have you ever seen a boundary?
I have never seen a boundary!
What I mean by that is, I have never seen a boundary as a batsman in cricket sport does.
A batsman is able to score four or a six because he knows where the boundary is. If the boundary kept changing, will the batsman ever be confident of scoring a four or six?
Here is a chat excerpt between me and a tester who is preparing himself for ISTQB!
CT: Pradeep, I have one doubt in testing.
CT: BVA for 4 to 10
CT: the values 3 4 5 9 10 11
CT: is it correct?
me: Man if it is this easy to do a boundary testing, anyone can do testing.
Also, have a look at a questions about boundary testing from a sample ISTQB exam paper:
7. Boundary value testing
a. Is the same as equivalence partitioning tests
b. Test boundary conditions on, below and above the edges of input and
output equivalence classes.
c. Tests combinations of input circumstances.
d. Is used in white box testing.
1. An input field takes the year of birth between 1900 and 2004
The boundary values for testing this field are
b. 1900, 2004
d. 1899, 1900, 1901,2003,2004,2005
In my opinion, a tester should be taught that there is no fixed boundary in software!
Here is my story of boundary testing of a multimedia product:
I was testing an audio decoder which was supposed to play any mp3 file ranging from 24 kbps to 196 kbps.
So is boundary testing of such a product something like playing 23 kbps, 24 kbps, 25 kbps, 195 kbps, 196 kbps, 197 kbps?
Huh! The version of software I got to test crashed when I played 96 kbps file and I also found that 128 kbps crashed the application, too.
Yes, I agree that it was supposed to play any value from 24 kbps to 196 kbps ( as per the specification). So does that mean, I did not do a boundary testing on the product because I did not use the value 195, 196 and 197?
Jeez! In my opinion, I did a a boundary testing. I did *explore* the program for it's boundary and found that the version of software I got had a boundary of 84 kbps and any value above which the application crashes ( smoothly) .
Despite 96 kbps and 128 kbps file crashed the application, had 196 kbps file played, does this mean there are more boundaries than you imagined?
Isn't it something like saying Pluto is the last planet in our Solar System and NASA coming out with photographs of a planet beyond Pluto that is a part of our solar system. (Wow! General Systems Thinking, is helping me a great deal)
The next version had a fix for the crash and it appeared to me that a 96 kbps file did not crash the application.
Now that's a story of how I conjecture that boundary is not a static in software. James Bach spoke about Boundary Testing in Becoming a Software Testing Expert Google Video and it gave me more new dimensions about boundary testing and a lot of other things, too. If you haven't watched it, you don't know the secrets of becoming a software testing expert :)
As a tester, I am never *sure* about something that I have observed or claim to know about testing but I am very sure that after reading this post, many testers would spark off with their experience and jump out to say, "I have seen a boundary" or " I did boundary testing the way you said is an incorrect way of doing it".
If I were you, here is what I might want to say, "Pradeep, I have done boundary testing in a way that you pointed out as incorrect. I might have failed to notice the thing that you have mentioned, probably because of a tunnel vision imparted to me. Let me do a few more experiments with it and get back to you".
That sounds great!
Have you ever wondered whether you can see James Bach and Mike Kelly exploring boundary of a software and testing it?
No more wonders, it is a reality! Download this video
The boundary does not exist in the software but it does, with your thoughts!
Pradeep's first language is not English--his first language appears to be testing. -- Michael Bolton
Update: BJ Rollison has made a post on this and left a comment in my blog too. I have replied to BJ Rollison in the comments section here.