Merge pull request #3 from senid231/add-send-metrics-matcher

add send_metrics matcher, add base_stats instrumentation tests

lib/prometheus_exporter/ext/rspec.rb

@@ -1,7 +1,17 @@
 # frozen_string_literal: true
 
+require 'prometheus_exporter/client'
 require_relative 'rspec/matchers'
+require_relative 'rspec/test_client'
+
+# Setups default client before it used anywhere.
+# use `include_examples :observes_prometheus_metrics` in specs
+PrometheusExporter::Client.default = PrometheusExporter::Ext::RSpec::TestClient.instance
 
 RSpec.configure do |config|
   config.include PrometheusExporter::Ext::RSpec::Matchers
+
+  config.before do
+    PrometheusExporter::Ext::RSpec::TestClient.instance.reset
+  end
 end

lib/prometheus_exporter/ext/rspec/matchers.rb

@@ -2,9 +2,14 @@
 
 require 'date'
 require_relative 'metric_matcher'
+require_relative 'send_metrics_matcher'
 
 module PrometheusExporter::Ext::RSpec
   module Matchers
+    def send_metrics(expected = nil)
+      PrometheusExporter::Ext::RSpec::SendMetricsMatcher.new(expected)
+    end
+
     def a_prometheus_metric(klass, name)
       MetricMatcher.new(klass, name)
     end

lib/prometheus_exporter/ext/rspec/send_metrics_matcher.rb

@@ -0,0 +1,86 @@
+# frozen_string_literal: true
+
+module PrometheusExporter::Ext::RSpec
+  class SendMetricsMatcher
+    include RSpec::Matchers::DSL::DefaultImplementations
+    include RSpec::Matchers
+    include RSpec::Matchers::Composable
+
+    attr_reader :expected, :actual
+
+    def initialize(expected)
+      @expected = expected&.map { |metric| deep_stringify_keys(metric) }
+      @ordered = false
+      @times = nil
+    end
+
+    def name
+      'sends metrics to prometheus'
+    end
+
+    def supports_block_expectations?
+      true
+    end
+
+    def matches?(actual_proc)
+      raise ArgumentError, "#{name} matcher supports only block expectations" unless actual_proc.is_a?(Proc)
+
+      metrics_before = PrometheusExporter::Ext::RSpec::TestClient.instance.metrics
+      actual_proc.call
+      metrics_after = PrometheusExporter::Ext::RSpec::TestClient.instance.metrics - metrics_before
+      @actual = metrics_after.map { |metric| deep_stringify_keys(metric) }
+
+      if expected
+        expected_value = @ordered ? expected : match_array(expected)
+        values_match?(expected_value, actual)
+      elsif @times
+        values_match?(@times, actual.size)
+      else
+        actual.size >= 1
+      end
+    end
+
+    def failure_message
+      if expected
+        expected_value = @ordered ? expected : match_array(expected)
+        +"expected #{name} to receive #{description_of(expected_value)}, but got\n    #{description_of(actual)}"
+      elsif @times
+        values_match?(@times, actual.size)
+        +"expected #{name} to receive #{@times} metrics, but got #{actual.size}\n    #{description_of(actual)}"
+      else
+        actual.size
+        +"expected #{name} to receive more than 1 metric, but got #{actual.size}\n    #{description_of(actual)}"
+      end
+    end
+
+    def ordered
+      raise ArgumentError, 'ordered cannot be when expected not provided' if expected.nil?
+      raise ArgumentError, 'ordered cannot be used with times' if @times
+
+      @ordered = true
+      self
+    end
+
+    def times(qty)
+      raise ArgumentError, 'times argument must be an integer' unless qty.is_a?(Integer)
+      raise ArgumentError, 'times argument must be >= 1' unless qty >= 1
+      raise ArgumentError, 'ordered cannot be when expected is provided' unless expected.nil?
+      raise ArgumentError, 'ordered cannot be used with times' if @ordered
+
+      @times = qty
+      self
+    end
+
+    def description_of(object)
+      RSpec::Support::ObjectFormatter.new(nil).format(object)
+    end
+
+    private
+
+    def deep_stringify_keys(hash)
+      hash.transform_keys(&:to_s).transform_values do |value|
+        value.is_a?(Hash) ? deep_stringify_keys(value) : value
+      end
+    end
+  end
+end

lib/prometheus_exporter/ext/rspec/test_client.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+require 'singleton'
+
+module PrometheusExporter::Ext::RSpec
+  class TestClient
+    include Singleton
+
+    def initialize
+      super
+      reset
+    end
+
+    def metrics
+      @metrics.dup
+    end
+
+    def send_json(data)
+      @metrics << data
+    end
+
+    def reset
+      @metrics = []
+    end
+
+    def stop
+      nil
+    end
+  end
+end

spec/prometheus_exporter/ext/instrumentation/base_stats_spec.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+RSpec.describe PrometheusExporter::Ext::Instrumentation::BaseStats do
+  subject do
+    instrumentation.collect(data_list)
+  end
+
+  let(:instrumentation) { TestInstrumentation.new }
+  let(:data_list) do
+    [
+      { foo: 123, bar: 456, labels: { qwe: 'asd' } },
+      { foo: 124, bar: 457, labels: { qwe: 'zxc' } }
+    ]
+  end
+
+  it 'sends metrics' do
+    expect { subject }.to send_metrics
+  end
+
+  it 'sends exactly 2 metrics' do
+    expect { subject }.to send_metrics.times(2)
+  end
+
+  it 'sends correct metrics' do
+    expect { subject }.to send_metrics(
+      [
+        {
+          type: 'test',
+          foo: 123, bar: 456,
+          labels: { qwe: 'asd' },
+          metric_labels: {}
+        },
+        {
+          type: 'test',
+          foo: 124, bar: 457,
+          labels: { qwe: 'zxc' },
+          metric_labels: {}
+        }
+      ]
+    )
+  end
+
+  context 'with empty data list' do
+    let(:data_list) { [] }
+
+    it 'sends correct metrics' do
+      expect { subject }.not_to send_metrics
+    end
+  end
+end

spec/spec_helper.rb

@@ -1,7 +1,19 @@
 # frozen_string_literal: true
 
+require 'prometheus_exporter'
 require 'prometheus_exporter/ext'
-require 'prometheus_exporter/ext/rspec/matchers'
+require 'prometheus_exporter/ext/rspec'
+require 'prometheus_exporter/ext/instrumentation/base_stats'
+
+class TestInstrumentation < PrometheusExporter::Ext::Instrumentation::BaseStats
+  self.type = 'test'
+
+  def collect(data_list)
+    data_list.each do |data|
+      collect_data(data)
+    end
+  end
+end
 
 RSpec.configure do |config|
   # Enable flags like --only-failures and --next-failure
@@ -13,6 +25,4 @@
   config.expect_with :rspec do |c|
     c.syntax = :expect
   end
-
-  config.include PrometheusExporter::Ext::RSpec::Matchers
 end