Change format of Rails/FindByOrAssignmentMemoization auto correct

[schinery]

Is your feature request related to a problem? Please describe.

The unsafe auto correct for Rails/FindByOrAssignmentMemoization added too many lines to a couple of admittedly bloated classes.

Describe the solution you'd like

When running the new Rails/FindByOrAssignmentMemoization cop with the -A flag it will do the following:

Changes:

def product
  @product ||= Product.find_by(code: params[:code])
end

To:

def product
  if instance_variable_defined?(:@product)
    @product
  else
    @product = Product.find_by(code: params[:code])
  end
end

To save a few lines, I was wondering if the format could be changed to?

def product
  return @product if instance_variable_defined?(:@product)

  @product = Product.find_by(code: params[:code])
end

[Earlopain]

I prefer this correction as well. You can even replace instance_variable_defined?(:@product) with just defined?(@product) to make it shorter still. I proposed some of this in the original PR but wasn't really convinced but now I don't really get anymore why I wouldn't be.

[Earlopain]

@koic this is not the correct change. This style of autocorrect only works when inside of a method (or similar), and that method contains no other code. Docs for the cop only show code where that is the case but it also handles anything else.

Returning early when other code is present changes meaning. I have changes locally to handle this correctly, I just need to write some tests later when I have time and will open a PR then.