I have an input value I wish to test where the acceptable range is 1..n (n is variable but always positive). To give it some context, n is the quantity of a product in stock at any one time (which changes day to day). A user may request to use 1 or up to n of these products at any one time but should be restricted if they request more than the value of n at that time.
To create test cases for the input value I thought I would apply equivalence partitioning and boundary value analysis to create classes and select the boundary values. However, I am not sure how you use these techniques to define test cases when the equivalence classes/boundary values of an input is variable.
Are the EP/BV techniques not applicable for this type of situation? How would one approach defining values for a test case?