Becoming Fiddler best friend: A use case that demostrate how to integrate tools to improve quality

I do have a special admiration for  Fiddler, because now more than ever, I’m able to exploit all the potential of that tool and because the scenarios I’m working on TeamMentor allow me to use it and taka advantage of it.

The problem

We had several automation test to check the functionality of the Singup form. At the time of creating that test, one of the issues found was the lack of validation for input text(which means that at the UI level you were able to put a large text) and the user creation was Ok.

Once this issue was fixed, our test as expected, started failing. Which  require us to enhance the test to cover the new scenario.

How to know if the issue was actually addressed?

In my prior test, I entered a long input text in the html form fields and TeamMentor was able to create a user. Now when I perform the same operation, I recieve a 0 value in the JSON response. This response means that  the user was not created and it drives to a generic error in the UI. Since our prior text was expecting to pass using a large payload, once the issue was solved, our test failes.

Failing response

Fiddler provides a drag and drop feature to edit and resent your request, you just need to move tot he Composer tab and drag and drop session 317. The using the request builder you can edit the parameters very easy. So I took the failing session and I modified the long text in the FirstName and LastName fields. Once the text lenght was acceptable (10 to 2o characters), I was able to receive a valid response indicating our customer was created.


This approach is very nice because we can combine tools to achieve our goals at TeamMentor.


About Michael Hidalgo

Michael is a Software Developer Engineer based on San José, Costa Rica. He leads the OWASP Chapter from Costa Rica. You can take a look at my blog at
This entry was posted in Fiddler, Fiddler Drag and Drop, Tools, UnitTests and tagged . Bookmark the permalink.

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