gitlab-ce/spec/lib/gitlab/experimentation_spec.rb

# frozen_string_literal: true

require 'spec_helper'

RSpec.describe Gitlab::Experimentation do
  using RSpec::Parameterized::TableSyntax

  before do
    stub_const('Gitlab::Experimentation::EXPERIMENTS', {
      test_experiment: {
        tracking_category: 'Team'
      },
      tabular_experiment: {
        tracking_category: 'Team',
        rollout_strategy: rollout_strategy
      }
    })

    skip_feature_flags_yaml_validation
    skip_default_enabled_yaml_check
    Feature.enable_percentage_of_time(:test_experiment_experiment_percentage, enabled_percentage)
    allow(Gitlab).to receive(:com?).and_return(true)
  end

  let(:enabled_percentage) { 10 }
  let(:rollout_strategy) { nil }

  describe '.get_experiment' do
    subject { described_class.get_experiment(:test_experiment) }

    context 'returns experiment' do
      it { is_expected.to be_instance_of(Gitlab::Experimentation::Experiment) }
    end

    context 'experiment is not defined' do
      subject { described_class.get_experiment(:missing_experiment) }

      it { is_expected.to be_nil }
    end
  end

  describe '.active?' do
    subject { described_class.active?(:test_experiment) }

    context 'feature toggle is enabled' do
      it { is_expected.to eq(true) }
    end

    describe 'experiment is not defined' do
      it 'returns false' do
        expect(described_class.active?(:missing_experiment)).to eq(false)
      end
    end

    describe 'experiment is disabled' do
      let(:enabled_percentage) { 0 }

      it { is_expected.to eq(false) }
    end
  end

  describe '.in_experiment_group?' do
    let(:enabled_percentage) { 50 }
    let(:experiment_subject) { 'z' } # Zlib.crc32('test_experimentz') % 100 = 33

    subject { described_class.in_experiment_group?(:test_experiment, subject: experiment_subject) }

    context 'when experiment is active' do
      context 'when subject is part of the experiment' do
        it { is_expected.to eq(true) }
      end

      context 'when subject is not part of the experiment' do
        let(:experiment_subject) { 'a' } # Zlib.crc32('test_experimenta') % 100 = 61

        it { is_expected.to eq(false) }
      end

      context 'when subject has a global_id' do
        let(:experiment_subject) { double(:subject, to_global_id: 'z') }

        it { is_expected.to eq(true) }
      end

      context 'when subject is nil' do
        let(:experiment_subject) { nil }

        it { is_expected.to eq(false) }
      end

      context 'when subject is an empty string' do
        let(:experiment_subject) { '' }

        it { is_expected.to eq(false) }
      end
    end

    context 'when experiment is not active' do
      before do
        allow(described_class).to receive(:active?).and_return(false)
      end

      it { is_expected.to eq(false) }
    end
  end

  describe '.log_invalid_rollout' do
    subject { described_class.log_invalid_rollout(:test_experiment, 1) }

    before do
      allow(described_class).to receive(:valid_subject_for_rollout_strategy?).and_return(valid)
    end

    context 'subject is not valid for experiment' do
      let(:valid) { false }

      it 'logs a warning message' do
        expect_next_instance_of(Gitlab::ExperimentationLogger) do |logger|
          expect(logger)
            .to receive(:warn)
                  .with(
                    message: 'Subject must conform to the rollout strategy',
                    experiment_key: :test_experiment,
                    subject: 'Integer',
                    rollout_strategy: :cookie
                  )
        end

        subject
      end
    end

    context 'subject is valid for experiment' do
      let(:valid) { true }

      it 'does not log a warning message' do
        expect(Gitlab::ExperimentationLogger).not_to receive(:build)

        subject
      end
    end
  end

  describe '.valid_subject_for_rollout_strategy?' do
    subject { described_class.valid_subject_for_rollout_strategy?(:tabular_experiment, experiment_subject) }

    where(:rollout_strategy, :experiment_subject, :result) do
      :cookie | nil       | true
      nil     | nil       | true
      :cookie | 'string'  | true
      nil     | User.new  | false
      :user   | User.new  | true
      :group  | User.new  | false
      :group  | Group.new | true
    end

    with_them do
      it { is_expected.to be(result) }
    end
  end
end