Category Archives: Edge Testing

Clarifying Edge Testing

I happened upon a very
interesting blog recently, searching for more examples of edge case testing,
wherein the author provides an interesting set of common edge cases. While they
use the same names or similar ones as those we’ve seen lately in class some
have new meaning here. In addition, they may have an actual value tied to the
name – such as zero, one, and two – but their values are defined otherwise.

 In order they
are as such:

  • Zero “represents
    any form of null input”, including the actual value zero but also null, an empty
    List or Array, et cetera. This of course is to test the capability of a program
    to deal with input that isn’t properly usable by it.
  • One represents what
    we have referred to as nominal up to this point, meaning a valid normal input
    which should test proper functionality of a program under ideal conditions.
  • Two does not
    correspond to the value two, but rather refers to testing the same code twice,
    usually in sequence, to see how repeated executions affect a system.
  • Two to Max-1 is
    most like one, in that it represents a nominal value as well, but in opposition
    this value should not be the absolute simplest needed to function but an average
    use case; meaning possibly complicated.
  • Max is
    fairly self-explanatory, used to test the upper limit accepted by a program, and
    can sometimes be an extreme value. As such, it can test the limits of the
    program under incredible load.
  • Max + 1 is
    used to ensure that limits placed on an application are working and that anything
    that does not correspond to a valid range is rejected in a reasonable manner.

These would most closely correspond to Normal Boundary Value Testing as we have covered in class but they are each less abstract than those counterparts. They provide an insight on what these values look like in actual QA testing, as well as expectations upon being used. Two for example does not have an actual value associated with it, but rather refers to a testing orthodoxy outlined above. One example of a test in this vein is found in another blog, in which the author proposes the edge case of the same user trying to log in from two different computers. I believe between the two of these blogs a clearer picture of the concepts we have covered can be found through these more concrete examples of the testing procedure.


A Beginner’s Guide to Testing: Error Handling Edge Cases
Build Strong Edge Test Cases

From the blog CS@Worcester – Press Here for Worms by wurmpress and used with permission of the author. All other rights reserved by the author.