singed_spec.rb

# frozen_string_literal: true

RSpec.describe Singed do
  around do |example|
    original_enabled = Singed.enabled?
    example.run
  ensure
    Singed.enabled = original_enabled
    Singed.instance_variable_set(:@current_flamegraph, nil)
  end

  describe ".start" do
    before { Singed.enabled = true }

    it "creates a current flamegraph and starts profiling" do
      current_flamegraph = Singed.start

      expect(current_flamegraph).to be_a(Singed::Flamegraph)
      expect(Singed.profiling?).to be true
      expect(current_flamegraph.started?).to be true
    end

    it "does nothing when already profiling" do
      Singed.start
      expect(Singed.start).to be_nil
    end

    it "does nothing when disabled" do
      Singed.enabled = false
      expect(Singed.start).to be_nil
      expect(Singed.profiling?).to be_falsey
    end
  end

  describe ".stop" do
    before do
      Singed.enabled = true
    end

    it "returns nil when not profiling" do
      expect(Singed.stop).to be_nil
    end

    it "stops profiling, saves the result file, and returns the flamegraph with profile data" do
      Singed.start
      # Run some code to generate profile samples
      100.times { 2**10 }
      flamegraph = Singed.stop

      expect(flamegraph).to be_a(Singed::Flamegraph)
      expect(Singed.profiling?).to be false

      # Profile data is returned (StackProf results hash)
      expect(flamegraph.profile).to be_a(Hash)
      expect(flamegraph.profile).to include(:mode, :version, :interval)
      expect(flamegraph.profile[:mode]).to eq(:wall)
      expect(flamegraph.profile[:samples]).to be >= 0
    end

    it "creates the result file on disk" do
      Singed.start
      100.times { 2**10 }
      flamegraph = Singed.stop

      expect(Pathname(flamegraph.filename)).to exist
    end
  end
end