Merge pull request #3036 from DataDog/non-monitor-detection

Steepfile

@@ -658,6 +658,7 @@ target :ddtrace do
   library 'sinatra'
   library 'google-protobuf'
   library 'protobuf-cucumber'
+  library 'minitest'
   library 'mysql2'
   library 'mysql2-aurora'
   library 'opentracing'

lib/datadog/core/environment/execution.rb

@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+
+module Datadog
+  module Core
+    module Environment
+      # Provides information about the execution environment on the current process.
+      module Execution
+        class << self
+          # Is this process running in a development environment?
+          # This can be used to make decisions about when to enable
+          # background systems like worker threads or telemetry.
+          def development?
+            !!(repl? || test?)
+          end
+
+          private
+
+          # Is this process running a test?
+          def test?
+            rspec? || minitest?
+          end
+
+          # Is this process running inside on a Read–eval–print loop?
+          # DEV: REPLs always set the program name to the exact REPL name.
+          def repl?
+            REPL_PROGRAM_NAMES.include?($PROGRAM_NAME)
+          end
+
+          REPL_PROGRAM_NAMES = %w[irb pry].freeze
+          private_constant :REPL_PROGRAM_NAMES
+
+          # RSpec always runs using the `rspec` file https://github.com/rspec/rspec-core/blob/main/exe/rspec
+          def rspec?
+            $PROGRAM_NAME.end_with?(RSPEC_PROGRAM_NAME)
+          end
+
+          RSPEC_PROGRAM_NAME = '/rspec'
+          private_constant :RSPEC_PROGRAM_NAME
+
+          # Check if Minitest is present and installed to run.
+          def minitest?
+            # Minitest >= 5
+            (defined?(::Minitest) &&
+              ::Minitest.class_variable_defined?(:@@installed_at_exit) &&
+              ::Minitest.class_variable_get(:@@installed_at_exit)) ||
+              # Minitest < 5
+              (defined?(::Minitest::Unit) &&
+                ::Minitest::Unit.class_variable_defined?(:@@installed_at_exit) &&
+                ::Minitest::Unit.class_variable_get(:@@installed_at_exit))
+          end
+        end
+      end
+    end
+  end
+end

sig/datadog/core/environment/execution.rbs

@@ -0,0 +1,19 @@
+module Datadog
+  module Core
+    module Environment
+      module Execution
+        def self.development?: () -> bool
+
+        private
+        def self.test?: () -> bool
+        def self.repl?: () -> bool
+
+        REPL_PROGRAM_NAMES: ::Array[::String]
+        def self.rspec?: () -> bool
+
+        RSPEC_PROGRAM_NAME: ::String
+        def self.minitest?: () -> bool
+      end
+    end
+  end
+end

spec/datadog/core/environment/execution_spec.rb

@@ -0,0 +1,87 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+require 'datadog/core/environment/execution'
+
+RSpec.describe Datadog::Core::Environment::Execution do
+  describe '#development?' do
+    subject(:development?) { described_class.development? }
+
+    context 'when in an RSpec test' do
+      it { is_expected.to eq(true) }
+    end
+
+    context 'when not in an RSpec test' do
+      # RSpec is detected through the $PROGRAM_NAME.
+      # Changing it will make RSpec detection to return false.
+      #
+      # We change the $PROGRAM_NAME instead of stubbing
+      # `Datadog::Core::Environment::Execution.rspec?` because
+      # otherwise we'll have no real test for non-RSpec cases.
+      around do |example|
+        begin
+          original = $PROGRAM_NAME
+          $PROGRAM_NAME = 'not-rspec'
+          example.run
+        ensure
+          $PROGRAM_NAME = original
+        end
+      end
+
+      let(:repl_script) do
+        <<-RUBY
+          # Load the working directory version of `ddtrace`
+          lib = File.expand_path('lib', __dir__)
+          $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
+          require 'datadog/core/environment/execution'
+
+          # Print actual value to STDERR, as STDOUT tends to have more noise in REPL sessions.
+          STDERR.print Datadog::Core::Environment::Execution.development?
+        RUBY
+      end
+
+      it 'ensure RSpec detection returns false' do
+        is_expected.to eq(false)
+      end
+
+      context 'when in an IRB session' do
+        it 'returns true' do
+          _, err = Bundler.with_clean_env do # Ruby 2.6 does not have irb by default in a bundle, but has it outside of it.
+            Open3.capture3('irb', '--noprompt', '--noverbose', stdin_data: repl_script)
+          end
+          expect(err).to end_with('true')
+        end
+      end
+
+      context 'when in a Pry session' do
+        it 'returns true' do
+          Tempfile.create('test') do |f|
+            f.write(repl_script)
+            f.close
+
+            out, = Open3.capture2e('pry', '-f', '--noprompt', f.path)
+            expect(out).to eq('true')
+          end
+        end
+      end
+
+      context 'when in a Minitest test' do
+        before { skip('Minitest not in bundle') unless Gem.loaded_specs['minitest'] }
+
+        it 'returns true' do
+          expect_in_fork do
+            # Minitest reads CLI arguments, but the current process has RSpec
+            # arguments that are not relevant (nor compatible) with Minitest.
+            # This happens inside a fork, thus we don't have to reset it.
+            Object.const_set('ARGV', [])
+
+            require 'minitest/autorun'
+
+            is_expected.to eq(true)
+          end
+        end
+      end
+    end
+  end
+end