Merge pull request #2 from senid231/add-test-gauge-with-time

add tests for gauge_with_time, add rspec matchers

lib/prometheus_exporter/ext/metric/gauge_with_time.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require 'prometheus_exporter/metric'
+require 'date'
 
 module PrometheusExporter::Ext::Metric
   class GaugeWithTime < PrometheusExporter::Metric::Gauge
@@ -41,6 +42,10 @@ def decrement(labels = {}, value = 1)
       result
     end
 
+    def to_h
+      super.to_h { |labels, value| [labels, [value, timestamps[labels]]] }
+    end
+
     private
 
     def update_timestamp(labels)

lib/prometheus_exporter/ext/rspec.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+require_relative 'rspec/matchers'
+
+RSpec.configure do |config|
+  config.include PrometheusExporter::Ext::RSpec::Matchers
+end

lib/prometheus_exporter/ext/rspec/matchers.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+require 'date'
+require_relative 'metric_matcher'
+
+module PrometheusExporter::Ext::RSpec
+  module Matchers
+    def a_prometheus_metric(klass, name)
+      MetricMatcher.new(klass, name)
+    end
+
+    # Matches approximate milliseconds since epoch
+    # @param date_time [DateTime] default DateTime.now
+    # @param delta [Integer] default 1000 ms
+    # @return [RSpec::Matchers::BuiltIn::BeWithin]
+    def ms_since_epoch(date_time: DateTime.now, delta: 1_000)
+      be_within(delta).of(date_time.strftime('%Q').to_i)
+    end
+
+    def a_gauge_metric(name)
+      a_prometheus_metric(PrometheusExporter::Metric::Gauge, name)
+    end
+
+    def a_gauge_with_time_metric(name)
+      a_prometheus_metric(PrometheusExporter::Ext::Metric::GaugeWithTime, name)
+    end
+
+    def a_counter_metric(name)
+      a_prometheus_metric(PrometheusExporter::Metric::Counter, name)
+    end
+
+    def a_histogram_metric(name)
+      a_prometheus_metric(PrometheusExporter::Metric::Histogram, name)
+    end
+
+    def a_summary_metric(name)
+      a_prometheus_metric(PrometheusExporter::Metric::Summary, name)
+    end
+  end
+end

lib/prometheus_exporter/ext/rspec/metric_matcher.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+module PrometheusExporter::Ext::RSpec
+  class MetricMatcher
+    include RSpec::Matchers::DSL::DefaultImplementations
+    include RSpec::Matchers
+    include RSpec::Matchers::Composable
+
+    attr_reader :metric_class, :metric_name, :metric_payload, :actual
+
+    def initialize(metric_class, metric_name)
+      @metric_class = metric_class
+      @metric_name = metric_name.to_s
+      @metric_payload = nil
+    end
+
+    def name
+      'be a prometheus metric'
+    end
+
+    def expected
+      "#{metric_class}(name=#{metric_name}, to_h=#{description_of(metric_payload)})"
+    end
+
+    def matches?(actual)
+      @actual = actual
+
+      return false unless values_match?(metric_class, actual.class)
+      return false unless values_match?(metric_name, actual.name.to_s)
+      return false if !metric_payload.nil? && !values_match?(metric_payload, actual.to_h)
+
+      true
+    end
+
+    def with(value, labels)
+      @metric_payload ||= {}
+      metric_payload[labels.transform_keys(&:to_s)] = value
+      self
+    end
+
+    def description_of(object)
+      RSpec::Support::ObjectFormatter.new(nil).format(object)
+    end
+  end
+end

spec/prometheus_exporter/ext/metric/gauge_with_time_spec.rb

@@ -0,0 +1,98 @@
+# frozen_string_literal: true
+
+require 'prometheus_exporter/ext/metric/gauge_with_time'
+
+RSpec.describe PrometheusExporter::Ext::Metric::GaugeWithTime do
+  describe '#to_prometheus_text' do
+    subject { metric.to_prometheus_text }
+
+    let(:metric) { described_class.new('metric_name', 'help_msg') }
+
+    it 'returns correct text' do
+      expect(subject).to eq("# HELP metric_name help_msg\n# TYPE metric_name gauge\n\n")
+    end
+
+    context 'with metric_text' do
+      let(:metric_text) { "metric_text 1\nmetric_text 2" }
+
+      before { allow(metric).to receive(:metric_text).once.and_return(metric_text) }
+
+      it 'returns correct text' do
+        title = "# HELP metric_name help_msg\n# TYPE metric_name gauge"
+        expect(subject).to eq("#{title}\n#{metric_text}\n")
+      end
+    end
+  end
+
+  describe '#metric_text' do
+    subject { metric.metric_text.split("\n") }
+
+    let(:metric) { described_class.new('metric_name', 'help_msg') }
+
+    it 'returns correct text' do
+      expect(subject).to eq([])
+    end
+
+    it 'has correct to_h' do
+      expect(metric.to_h).to eq({})
+    end
+
+    context 'when metric has data with stubbed timestamps' do
+      let!(:date_time_old) { DateTime.now - 25 }
+      let!(:date_time_new) { DateTime.now }
+
+      before do
+        allow(DateTime).to receive(:now).once.and_return(date_time_old)
+        metric.observe(1, 'foo' => 'bar')
+
+        allow(DateTime).to receive(:now).once.and_return(date_time_new)
+        metric.observe(2, 'baz' => 'boo')
+      end
+
+      it 'returns correct text' do
+        expect(subject).to contain_exactly(
+          %(metric_name{foo="bar"} 1 #{date_time_old.strftime('%Q').to_i}),
+          %(metric_name{baz="boo"} 2 #{date_time_new.strftime('%Q').to_i})
+        )
+      end
+
+      it 'has correct to_h' do
+        expect(metric.to_h).to match(
+          {
+            { 'foo' => 'bar' } => [1, date_time_old.strftime('%Q').to_i],
+            { 'baz' => 'boo' } => [2, date_time_new.strftime('%Q').to_i]
+          }
+        )
+      end
+
+      it 'matches a_gauge_with_time_metric' do
+        expect(metric).to a_gauge_with_time_metric('metric_name')
+          .with([1, date_time_old.strftime('%Q').to_i], foo: 'bar')
+          .with([2, date_time_new.strftime('%Q').to_i], baz: 'boo')
+      end
+    end
+
+    context 'when metric has data without stubbed timestamps' do
+      before do
+        metric.observe(1, 'foo' => 'bar')
+        sleep 0.2
+        metric.observe(2, 'baz' => 'boo')
+      end
+
+      it 'has correct to_h' do
+        expect(metric.to_h).to match(
+          {
+            { 'foo' => 'bar' } => [1, ms_since_epoch],
+            { 'baz' => 'boo' } => [2, ms_since_epoch]
+          }
+        )
+      end
+
+      it 'matches a_gauge_with_time_metric' do
+        expect(metric).to a_gauge_with_time_metric('metric_name')
+          .with([1, ms_since_epoch], foo: 'bar')
+          .with([2, ms_since_epoch], baz: 'boo')
+      end
+    end
+  end
+end

spec/prometheus_exporter/ext_spec.rb

@@ -4,8 +4,4 @@
   it 'has a version number' do
     expect(PrometheusExporter::Ext::VERSION).not_to be_nil
   end
-
-  it 'does something useful' do
-    expect(false).to be(true)
-  end
 end

spec/spec_helper.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require 'prometheus_exporter/ext'
+require 'prometheus_exporter/ext/rspec/matchers'
 
 RSpec.configure do |config|
   # Enable flags like --only-failures and --next-failure
@@ -12,4 +13,6 @@
   config.expect_with :rspec do |c|
     c.syntax = :expect
   end
+
+  config.include PrometheusExporter::Ext::RSpec::Matchers
 end