How to fail a particular HTTP call through Fiddler?

I am a Quality Engineer who test a lot of things in softwares. Currently I am working on a hybrid application where a desktop software make some internet calls.

Recently I came across a scenario where I wanted to fail a particular call in middle of a set of HTTP calls. Fiddler helped me to do so.

Here are the steps to make this happen:

I am taking an example for explaining this. Lets take a case where one thread make 5 calls Call-1, Call-2....Call-5 and I want to fail Call-3. Here are the steps I need to follow:

- Run this thread after starting fiddler.
- It will list all five calls.
- Select Call-3 and select AutoResponder Tab on the right side
- Check the option for "Enable Automatic Responses"
- Click Add Button
- Call-1 URL will be listed in Rule Editor in Right-Bottom
- Enter any random value in other text-box on the right side of Rule-Editor.
- Save this.

In future whenever you will run this thread, Call-3 will always fail.

All the Best!!!