RSpec.describe Mutest::Integration::Null do let(:object) { described_class.new(Mutest::Config::DEFAULT) } describe '#all_tests' do subject { object.all_tests } it { is_expected.to eql([]) } it_should_behave_like 'an idempotent method' end describe '#call' do subject { object.call(tests) } let(:tests) { instance_double(Array) } it 'returns test result' do is_expected.to eql( Mutest::Result::Test.new( output: '', passed: true, runtime: 0.0, tests: tests ) ) end end end