Can someone help me make this code not suck?

require 'test/unit'

# EWWWWWWW
def process_string str
  result = Hash.new
  str.to_a.each do |line|
    line.scan(/important ([a-zA-Z0-9]+): /) do |key|
      result[key.first] = line
    end
  end
  result
end

class TestThis < Test::Unit::TestCase
  def example_string
    <<-END
    # comments
    important key1: some value's here
    important key2: some value's here
    important key3: some value's here
    important key4: some value's here

    other stuff we don't care about
    END
  end

  def test_process_string
    result = process_string example_string
    assert 4, result.size
    assert result.has_key?("key1")
    assert result.has_key?("key2")
    assert result.has_key?("key3")
    assert result.has_key?("key4")
  end
end