span_spec.rb

  describe "#overlaps?(span)" do
    def span(lower, upper)
      Search::Span.new(lower, upper)
    end

    def overlap(expected)
      simple_matcher do |given, matcher|
        matcher.description = "overlap with #{expected}"
        matcher.failure_message = "expected #{given} to overlap with #{expected}"
        matcher.negative_failure_message = "expected #{given} not to overlap with #{expected}"
        given.overlaps?(expected) and expected.overlaps?(given)
      end
    end

    it "should tell whether two spans will overlap" do
      span(5, 15).should overlap(span(5, 15))
      span(5, 15).should overlap(span(0, 10))
      span(5, 15).should overlap(span(10, 20))
      span(5, 15).should overlap(span(0, 20))
      span(5, 15).should overlap(span(0, 5))
      span(5, 15).should overlap(span(15, 20))

      span(5, 15).should_not overlap(span(0, 4))
      span(5, 15).should_not overlap(span(16, 20))

      span(5, 15).should overlap(span(nil, 10))
      span(5, 15).should overlap(span(nil, 20))
      span(nil, 15).should overlap(span(nil, 20))
      span(5, 15).should overlap(span(10, nil))

      span(5, 15).should_not overlap(span(nil, 0))
      span(5, 15).should_not overlap(span(20, nil))
    end
  end