Feature Request: Select block of code/method, hit key, shows example execution

Here's a feature that I think could offer a major advantage for IntelliJ - as important as code navigation and refactoring.

Imagine I have some code:

public String doSomething(String s) {
  return s + " hello " + s.trim();

And some other code:

// bunch of stuff

Now, currently, with the cursor on doSomething, I can hit ctrl-shift-i to show the underlying code.

What  would be awesome is if I could hit another keystroke (or maybe the  same) and it would popup a table showing some example inputs and  results.


Input Results
null NPE
"" " hello "
"example" "example hello example"
" example " "  example  hello example"
"Exa MPLE" "Exa MPLE hello Exa MPLE"

Potential issues:
-  coming up with list of inputs - really not that hard - for Strings, the  list above would be enough to cater for a lot of cases - alternatively,  it could be interactive, have an editable textbox for each input, run  the code and update the results on the fly as you type, like the Regex  plugin
- complex parameters - ie compound objects - that's ok,  just don't support that use case initially, just handling Strings and  primitives would be great initially

If not a core part of the product, maybe someone keen could hack up a plugin to demonstrate the concept.

BTW I originally posted this in the EAP discussion group but then looked at the list of recent messages and it appears very dead... - so posting it here instead.


I think this cannot be implemented in any useful way.
There are simply too many potential inputs/outputs/side effects to the code. How about arbritratry objects that are passed to code (how would you supply a JFrame or a hibernate session object to the code). How should IDEA setup referenced object graphs?

If I want to test-drive the code I use the debugger or write unit tests. Also I would complain to the original developer about missing Javadoc.


How would you handle JFrame or hibernate objects? Don't deal with those cases.
There are a lot of complexities but that's what JetBrains are good at dealing with.
The  same kind of objections were probably voiced before the Extract Method  refactoring became common. There are all sorts of cases where a code  selection means that extract method is not possible - don't worry about  those, work on the cases where it can work.

Complaining to the original dev is not an option when you're working on some 8 year old codebase at Megacorp X.


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