Ruby Rspec - Class example

uniqueness_validator_spec.rb

class UniquenessValidator
  def initialize(sources: [])
    @sources = sources
  end

  def run
    # 'admin_intro_crm_basics', 'lex_migration_introduction', 'admin_intro_crm_basics'
    top_level_ids = sources.map(&:find_all_top_level_ids).flatten
    calculate_repeated!(top_level_ids)
    self
  rescue => e
    add_error!(e.message)
    self
  end

  def repeated_ids
    @repeated_ids || []
  end

  def error_messages
    @error_messages || []
  end

  private

  def calculate_repeated!(top_level_ids)
    @repeated_ids =
      top_level_ids                 # ['id1', 'id1', 'id2']
      .group_by { |e| e }           # [ ['id1', ['id1', 'id1']], ['id2', ['id2']] ]
      .select { |_, v| v.size > 1 } # [ ['id1', ['id1', 'id1']] ]
      .map(&:first)                 # ['id1']
  end

  def add_error!(error_message)
    @error_messages ||= []
    @error_messages << "Error: #{error_message}"
  end

  attr_reader :sources
end

describe UniquenessValidator do
  describe '#run' do
    subject(:validator) { described_class.new(sources: [source_explorer]) }
    let(:ids) { %w(id1 id2 id3) }
    let(:source_explorer) { double(find_all_top_level_ids: ids) }

    it 'asks the source explorer for all top level ids' do
      validator.run
      expect(source_explorer).to have_received(:find_all_top_level_ids)
    end

    context 'when ids are repetead across multiple sources' do
      let(:git_source_explorer) { double(find_all_top_level_ids: %w(id1 id2 id3)) }
      let(:p4_source_explorer) { double(find_all_top_level_ids: %w(id4 id2 id5)) }
      subject(:validator) do
        described_class.new(sources: [git_source_explorer, p4_source_explorer])
      end

      it 'identifies its repetition' do
        validator.run
        expect(validator.repeated_ids).to match_array(%w(id2))
      end
    end

    context 'when no id is repeated' do
      it 'does not populate repeated_ids' do
        result = validator.run
        expect(result.repeated_ids).to be_empty
      end
    end

    context 'when one id is repeated' do
      let(:ids) { %w(id1 id2 id1) }
      it 'populates repeated_ids' do
        result = validator.run
        expect(result.repeated_ids).to match_array(['id1'])
      end
    end

    context 'when multiple ids are reapeated' do
      let(:ids) { %w(id1 id2 id1 id3 id3 id3 id4 id5) }
      it 'populates repeated_ids' do
        result = validator.run
        expect(result.repeated_ids).to match_array %w(id1 id3)
      end
    end

    it 'populates its error_messages with nothing' do
      result = validator.run
      expect(result.error_messages).to be_empty
    end

    context 'when source explorer fails' do
      it 'populates its error_messages' do
        allow(source_explorer).to receive(:find_all_top_level_ids).and_raise('message')
        result = validator.run
        expect(result.error_messages).to eq(['Error: message'])
      end
    end
  end
end