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A brief Introduction to Boundary Value Analysis

In Testing Methodologies on January 3, 2011 at 12:40 pm

Jack and Tom were next door neighbours.  Theirr home were seperated bya  compound wall which was not thick enough for a person to walk  comfortably.  People would fall if they were not careful enough. Jack and tom were discussed  a bet.  The bet was to walk on the compound wall seperating their two homes, without falling down.  Whoever achieved this would win the bet. 

       Boundary value analysis is probably one of the most elementary of test methods.  It is like walking on the compound wall mentioned above. The belief is that, if a person can walk on that compound wall, it can be safely said that he will be able to walk on the ground easily.

       When you have lots of input data, you could partition the input domain and select values that lie on the boundaries of this partition.  If the application does not throw any error, it can be assumed that the application would work fine for data values from inside the input domain.

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A brief introduction to Equivalence Classes

In Testing Methodologies on December 30, 2010 at 1:16 pm

1000 Apples 900 Oranges 1400 Guavas have arrived ina truck.

You have only a few minutes to examine them. What would be the

best way to do this?
One way to do this would be to pick one or two fruits

from each category (Apples, Oranges, Guavas) and see if they

are good.

This is an analogy for equivalence classes. Each class is a

class of fruit. The fruits domain has three types of fruits

Apples, Oranges and Guavas. Hence 3 equivalence classes.

Lets look at another example:
We have an input domain allowed between 1 to 100 (intergers

only, no decimals or fractions allowed), to be fed to our

application under test – what could be the valid equivalence

classes?
Ans: The range of 1 to 100 comprises of 3 equivalence classes, namely: single digit (0-9), double digit (10-99), triple digit (100). If the user wants to test the application he just needs to select just one input from each of the three ranges. This avoids the tester from testing the application using each of the numbers from 1 to 100. The testing can be completed by just using 3 values!.

The above examples clearly show that testers in their daily lives have to deal with vast amounts of data. They can definitely divide the input data into valid and invalid (more on this later) equivalence classes, and select just one or two samples from each of the domain to safely say that there has been a good coverage in terms of input.

Divide and Rule rules!!!

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