class RuboCop::Cop::Style::SpaceBeforeComment

same line.
This cop checks for missing space between a token and a comment on the

def autocorrect(range) 

def autocorrect(range)
  @corrections << lambda do |corrector|
    corrector.insert_before(range, ' ')
  end
end

def investigate(processed_source) 

def investigate(processed_source)
  processed_source.tokens.each_cons(2) do |t1, t2|
    next unless t2.type == :tCOMMENT
    next unless t1.pos.line == t2.pos.line
    add_offense(t2.pos, t2.pos) if t1.pos.end == t2.pos.begin
  end
end