Compare the 'schema' of two hashes

results.txt

Hash#structurally_equal?
  when compared with a single-level hash
    with the same keys
      should be true
    with different keys
      should be false
    with more keys
      should be false
    with less keys
      should be false
  when compared with a multi-level hash
    with the same keys at all levels
      should be true
    with different keys at a lower level
      should be false

Finished in 0.00143 seconds
6 examples, 0 failures

structurally_equal.rb

require 'rspec'
require 'set'

class Hash
  def structurally_equal?(other)
    return false unless Set.new(keys) == Set.new(other.keys)
    nested = values.select { |v| v.respond_to? :keys }
    other_nested = other.values.select { |v| v.respond_to? :keys }
    nested.zip(other_nested).all? { |(n, o)| n.structurally_equal? o }
  end
end

describe Hash, '#structurally_equal?' do
  IRRELEVANT = :chunky_bacon

  subject { object.structurally_equal?(other) }

  context 'when compared with a single-level hash' do
    context 'with the same keys' do
      let(:object) { { a: IRRELEVANT, b: IRRELEVANT } }
      let(:other)  { { a: IRRELEVANT, b: IRRELEVANT } }

      it { should be_true }
    end

    context 'with different keys' do
      let(:object) { { a: IRRELEVANT, b: IRRELEVANT } }
      let(:other)  { { a: IRRELEVANT, c: IRRELEVANT } }

      it { should be_false }
    end

    context 'with more keys' do
      let(:object) { { a: IRRELEVANT }                }
      let(:other)  { { a: IRRELEVANT, c: IRRELEVANT } }

      it { should be_false }
    end

    context 'with less keys' do
      let(:object) { { a: IRRELEVANT, b: IRRELEVANT } }
      let(:other)  { { a: IRRELEVANT }                }

      it { should be_false }
    end
  end

  context 'when compared with a multi-level hash' do
    context 'with the same keys at all levels' do
      let(:object) { { a: { b: { c: IRRELEVANT } } } }
      let(:other)  { { a: { b: { c: IRRELEVANT } } } }

      it { should be_true }
    end

    context 'with different keys at a lower level' do
      let(:object) { { a: { b: { c: IRRELEVANT } } } }
      let(:other)  { { a: { b: { d: IRRELEVANT } } } }

      it { should be_false }
    end
  end
end