require 'spec_helper' describe JsonFileWriter do let(:writer) { described_class.new } describe '#write_enumerable' do let(:file) { StringIO.new } let(:enumerable) { [item_1, item_2] } let(:item_1) { double('item_1', :to_json => 'a') } let(:item_2) { double('item_2', :to_json => 'b') } subject { writer.write_enumerable(file, enumerable) } before do subject end it 'writes the enumerable to the file in json format' do expect(file.string).to eq('[a,b]') end it 'closes the file' do expect(file).to be_closed end end end