require 'spec_helper'

describe Immutable::List do
  let(:list) { L[*values] }

  describe '#flat_map' do
    let(:block) { ->(item) { [item, item + 1, item * item] } }
    let(:flat_map) { list.flat_map(&block) }
    let(:flattened_list) { L[*flattened_values] }

    shared_examples 'checking flattened result' do

      it 'returns the flattened values as a Immutable::List' do
        expect(flat_map).to eq(flattened_list)
      end

      it 'returns a Immutable::List' do
        expect(flat_map).to be_a(Immutable::List)
      end
    end

    context 'with an empty list' do
      let(:values) { [] }
      let(:flattened_values) { [] }

      include_examples 'checking flattened result'
    end

    context 'with a block that returns an empty list' do
      let(:block) { ->(item) { [] } }
      let(:values) { [1, 2, 3] }
      let(:flattened_values) { [] }

      include_examples 'checking flattened result'
    end

    context 'with a list of one item' do
      let(:values) { [7] }
      let(:flattened_values) { [7, 8, 49] }

      include_examples 'checking flattened result'
    end

    context 'with a list of multiple items' do
      let(:values) { [1, 2, 3] }
      let(:flattened_values) { [1, 2, 1, 2, 3, 4, 3, 4, 9] }

      include_examples 'checking flattened result'
    end
  end
end