constantize sampling percentages and nonce fallback

Author: joshuay03

lib/dial/configuration.rb

@@ -12,8 +12,8 @@ def self._configuration
   class Configuration
     def initialize
       @options = {
-        sampling_percentage: ::Rails.env.development? ? 100 : 1,
-        content_security_policy_nonce: -> (env, _headers) { env[NONCE] || "" },
+        sampling_percentage: ::Rails.env.development? ? SAMPLING_PERCENTAGE_DEV : SAMPLING_PERCENTAGE_PROD,
+        content_security_policy_nonce: -> (env, _headers) { env[NONCE] || EMPTY_NONCE },
         vernier_interval: VERNIER_INTERVAL,
         vernier_allocation_interval: VERNIER_ALLOCATION_INTERVAL,
         prosopite_ignore_queries: PROSOPITE_IGNORE_QUERIES,

lib/dial/constants.rb

@@ -18,6 +18,10 @@ module Dial
 
   FILE_STALE_SECONDS = 60 * 60
 
+  SAMPLING_PERCENTAGE_DEV = 100
+  SAMPLING_PERCENTAGE_PROD = 1
+  EMPTY_NONCE = ""
+
   VERNIER_INTERVAL = 200
   VERNIER_ALLOCATION_INTERVAL = 2_000
   VERNIER_PROFILE_OUT_RELATIVE_DIRNAME = "tmp/dial/profiles"