remove_whitespace.rb

require 'rspec'

def remove_whitespace(string)
  lines = string.lines
  # remove leading and trailing blank lines
  lines.shift while lines.first.strip.empty?
  lines.pop while lines.last.strip.empty?
  # remove trailing whitespace from lines
  lines.map(&:rstrip).join("\n")
end

describe do
  let(:str) do
    '

  blue
 green
    '
  end

  it do
    expect(remove_whitespace(str)).to eq('  blue
 green')
  end
end

I used this to compare config files in a way that most config parsers would (ignore whitespace that doesnt effect anything)