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contain_exactly matcher

The contain_exactly matcher provides a way to test arrays against each other in a way that disregards differences in the ordering between the actual and expected array. For example:

expect([1, 2, 3]).to    contain_exactly(2, 3, 1) # pass
expect([:a, :c, :b]).to contain_exactly(:a, :c ) # fail

This matcher is also available as match_array, which expects the expected array to be given as a single array argument rather than as individual splatted elements. The above could also be written as:

expect([1, 2, 3]).to    match_array [2, 3, 1] # pass
expect([:a, :c, :b]).to match_array [:a, :c]  # fail

Array is expected to contain every value​

Given a file named "contain_exactly_matcher_spec.rb" with:

RSpec.describe [1, 2, 3] do
  it { is_expected.to contain_exactly(1, 2, 3) }
  it { is_expected.to contain_exactly(1, 3, 2) }
  it { is_expected.to contain_exactly(2, 1, 3) }
  it { is_expected.to contain_exactly(2, 3, 1) }
  it { is_expected.to contain_exactly(3, 1, 2) }
  it { is_expected.to contain_exactly(3, 2, 1) }

  # deliberate failures
  it { is_expected.to contain_exactly(1, 2, 1) }
end

When I run rspec contain_exactly_matcher_spec.rb

Then the output should contain "7 examples, 1 failure"

And the output should contain:

     Failure/Error: it { is_expected.to contain_exactly(1, 2, 1) }

       expected collection contained:  [1, 1, 2]
       actual collection contained:    [1, 2, 3]
       the missing elements were:      [1]
       the extra elements were:        [3]

Array is not expected to contain every value​

Given a file named "contain_exactly_matcher_spec.rb" with:

RSpec.describe [1, 2, 3] do
  it { is_expected.to_not contain_exactly(1, 2, 3, 4) }
  it { is_expected.to_not contain_exactly(1, 2) }

  # deliberate failures
  it { is_expected.to_not contain_exactly(1, 3, 2) }
end

When I run rspec contain_exactly_matcher_spec.rb

Then the output should contain "3 examples, 1 failure"

And the output should contain:

     Failure/Error: it { is_expected.to_not contain_exactly(1, 3, 2) }
       expected [1, 2, 3] not to contain exactly 1, 3, and 2