require 'spec_helper' describe Gitlab::Metrics::Samplers::RubySampler do let(:sampler) { described_class.new(5) } let(:null_metric) { double('null_metric', set: nil, observe: nil) } before do allow(Gitlab::Metrics::NullMetric).to receive(:instance).and_return(null_metric) end after do Allocations.stop if Gitlab::Metrics.mri? end describe '#sample' do it 'samples various statistics' do expect(Gitlab::Metrics::System).to receive(:memory_usage) expect(Gitlab::Metrics::System).to receive(:file_descriptor_count) expect(sampler).to receive(:sample_gc) sampler.sample end it 'adds a metric containing the memory usage' do expect(Gitlab::Metrics::System).to receive(:memory_usage).and_return(9000) expect(sampler.metrics[:memory_usage]).to receive(:set).with({}, 9000) sampler.sample end it 'adds a metric containing the amount of open file descriptors' do expect(Gitlab::Metrics::System).to receive(:file_descriptor_count) .and_return(4) expect(sampler.metrics[:file_descriptors]).to receive(:set).with({}, 4) sampler.sample end it 'clears any GC profiles' do expect(GC::Profiler).to receive(:clear) sampler.sample end end describe '#sample_gc' do it 'adds a metric containing garbage collection time statistics' do expect(GC::Profiler).to receive(:total_time).and_return(0.24) expect(sampler.metrics[:total_time]).to receive(:set).with({}, 240) sampler.sample end it 'adds a metric containing garbage collection statistics' do GC.stat.keys.each do |key| expect(sampler.metrics[key]).to receive(:set).with({}, anything) end sampler.sample end end end