Add configuration for logger

lib/fulfil/client.rb

@@ -175,7 +175,7 @@ def request(endpoint:, verb: :get, **args)
     end
 
     def client
-      client = HTTP.use(logging: @debug ? { logger: Logger.new($stdout) } : {})
+      client = HTTP.use(logging: @debug ? { logger: config.logger } : {})
       client = client.auth("Bearer #{@token}") if @token
       client.headers(@headers)
     end

lib/fulfil/configuration.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'logger'
+
 module Fulfil
   # The `Fulfil::Configuration` contains the available configuration options
   # for the `Fulfil` gem.
@@ -22,9 +24,21 @@ class Configuration
     # @return [Proc, nil]
     attr_accessor :rate_limit_notification_handler
 
+    # Allows the client to configure a logger. Logs output to STDOUT by default.
+    #
+    # @return [Logger, nil]
+    #
+    # @example Use a logger to log the API rate limit hits
+    #  Fulfil.configure do |config|
+    #    config.logger = Logger.new(STDOUT)
+    #  end
+    #
+    attr_accessor :logger
+
     def initialize
       @retry_on_rate_limit = false
       @retry_on_rate_limit_wait = 1
+      @logger = Logger.new($stdout)
     end
 
     def retry_on_rate_limit?

test/fulfil/configuration_test.rb

@@ -13,5 +13,17 @@ def test_retry_on_rate_limit?
         assert_predicate Fulfil.config, :retry_on_rate_limit?
       end
     end
+
+    def test_default_logger
+      assert_instance_of Logger, Fulfil.config.logger
+    end
+
+    def test_configured_logger
+      with_fulfil_config do |config|
+        config.logger = Logger.new('test.log')
+      end
+
+      assert_instance_of Logger, Fulfil.config.logger
+    end
   end
 end