cover matcher

Use the cover matcher to specify that a range covers one or more expected objects. This works on any object that responds to #cover? (such as a Range):

    expect(1..10).to cover(5)
    expect(1..10).to cover(4, 6)
    expect(1..10).not_to cover(11)

Range usage

Given a file named “rangecovermatcher_spec.rb” with:

RSpec.describe (1..10) do
  it { is_expected.to cover(4) }
  it { is_expected.to cover(6) }
  it { is_expected.to cover(8) }
  it { is_expected.to cover(4, 6) }
  it { is_expected.to cover(4, 6, 8) }
  it { is_expected.not_to cover(11) }
  it { is_expected.not_to cover(11, 12) }

  # deliberate failures
  it { is_expected.to cover(11) }
  it { is_expected.not_to cover(4) }
  it { is_expected.not_to cover(6) }
  it { is_expected.not_to cover(8) }
  it { is_expected.not_to cover(4, 6, 8) }

  # both of these should fail since it covers 5 but not 11
  it { is_expected.to cover(5, 11) }
  it { is_expected.not_to cover(5, 11) }
end

When I run rspec range_cover_matcher_spec.rb

Then the output should contain all of these:
14 examples, 7 failures
expected 1..10 to cover 11
expected 1..10 not to cover 4
expected 1..10 not to cover 6
expected 1..10 not to cover 8
expected 1..10 not to cover 4, 6, and 8
expected 1..10 to cover 5 and 11
expected 1..10 not to cover 5 and 11