Add new CountAsOne option for code length related Metric cops

[fatkodima]

Closes #7724

This new setting allows to specify which ruby construction (array, hash and heredoc are currently implemented) we want to treat as one line.

The algorithm from the high level:

1. we calculate the total length for the whole code of specified node
2. then, for each the most top level descendant of foldable type, we returning back its code length to the total length
3. and so after steps 1 and 2 we get a resulted length

[Drenmi]

Great start!

I have been thinking about a similar setting myself, but the point I kept getting stuck at is the fact that arrays and hashes can have arbitrary amounts of code in them.

In the test cases for this configuration option, all the arrays and hashes are assumed to be shallow collections of primitive values, which is the case where this makes sense. But I must assume this introduces some false negatives? 🤔

[fatkodima]

In the test cases for this configuration option, all the arrays and hashes are assumed to be shallow collections of primitive values

No, the code works for arbitrary complex arrays/hashes. For example, the multiline array in the original issue would be folded into 1 line.
Looks like I missed to add test cases for more complex examples.

But I must assume this introduces some false negatives? 🤔

Am I answered also this question or should you provide an example then, if not?

[bbatsov]

Yeah, it'd be nice if there are some examples in the cop's description about using this new config.

[fatkodima]

Updated with suggestions.

[bbatsov]

Thanks!

[colinlieberman]

@fatkodima - I know this is 8 months old now, but I found it today, updated rubocop to the latest version, and am very, very happy. Thank you for this