Don't include started_at in metadata

Author: dalehamel

lib/app_profiler/backend/vernier_backend.rb

@@ -15,6 +15,10 @@ class VernierBackend < BaseBackend
         :retained,
       ].freeze
 
+      PRIVATE_METADATA = [
+        :started_at, # started_at uses a monotonic source, not realtime
+      ].freeze
+
       class << self
         def name
           :vernier
@@ -77,7 +81,7 @@ def results
         return unless vernier_profile
 
         # Store all vernier metadata
-        meta = vernier_profile.meta.reject { |k, v| k == :user_metadata || v.nil? }
+        meta = vernier_profile.meta.reject { |k, v| k == :user_metadata || v.nil? || PRIVATE_METADATA.include?(k) }
         meta.merge!(@metadata) if @metadata
 
         # Internal metadata takes precedence over user metadata, but store

test/app_profiler/backend/vernier_backend_test.rb

@@ -204,7 +204,6 @@ def teardown
       test ".results contain vernierUserMetadata, and extra meta" do
         skip "metadata output added in >=1.7.0" if Gem.loaded_specs["vernier"].version < Gem::Version.new("1.7.0")
 
-        initial_time = Process.clock_gettime(Process::CLOCK_MONOTONIC, :nanosecond)
         profile = AppProfiler.profiler.run(
           vernier_params(
             interval: 2000,
@@ -219,12 +218,17 @@ def teardown
         end
 
         assert_instance_of(AppProfiler::VernierProfile, profile)
+
         # Stores "internal" vernier metadata
         assert_equal(:wall, profile.metadata[:mode])
         assert_equal(2000, profile.metadata[:interval]) # The internal value takes precedence over the user value
         assert_equal(0, profile.metadata[:allocation_interval])
         assert_equal(false, profile.metadata[:gc])
-        assert_operator(initial_time, :<=, profile.metadata[:started_at])
+
+        # Don't include ignored/private metadata
+        AppProfiler::Backend::VernierBackend::PRIVATE_METADATA.each do |excluded|
+          refute_includes(profile.metadata, excluded)
+        end
 
         # Stores the user supplied data
         assert_equal("foo", profile.metadata[:user_data_1])