(FACT-2320) added warnonce method

lib/facter.rb

@@ -13,6 +13,7 @@ class ResolveCustomFactError < StandardError; end
   Options.init
   Log.output(STDOUT)
   @already_searched = {}
+  @warn_once = []
 
   class << self
     def clear_messages
@@ -54,6 +55,7 @@ def add(name, options = {}, &block)
     # @api public
     def clear
       @already_searched = {}
+      @warn_once = []
       LegacyFacter.clear
       Options[:custom_dir] = []
       LegacyFacter.collection.invalidate_custom_facts
@@ -262,6 +264,22 @@ def log_exception(exception, message = :default)
       logger.error(arr.flatten.join("\n"))
     end
 
+    # Logs only once the same warning message.
+    #
+    # @param message [Object] the warning message object
+    #
+    # @return [nil]
+    #
+    # @api public
+    def warnonce(message)
+      message_string = message.to_s
+      return if @warn_once.include? message_string
+
+      @warn_once << message_string
+      logger.warn(message_string)
+      nil
+    end
+
     private
 
     def logger

lib/facter/framework/logging/logger.rb

@@ -82,9 +82,7 @@ def info(msg)
     end
 
     def warn(msg)
-      if msg.nil? || msg.empty?
-        empty_message_error(msg)
-      elsif @@message_callback
+      if @@message_callback
         @@message_callback.call(:warn, msg)
       else
         msg = colorize(msg, YELLOW) if Options[:color]

spec/facter/facter_spec.rb

@@ -380,4 +380,45 @@ def mock_collection(method, os_name = nil, error = nil)
       end
     end
   end
+
+  describe '#warnonce' do
+    before do
+      allow(logger).to receive(:warn)
+    end
+
+    it 'calls logger with the warning message' do
+      message = 'Some error message'
+
+      Facter.warnonce(message)
+
+      expect(logger).to have_received(:warn).with(message)
+    end
+
+    it 'writes the same warning message only once' do
+      message = 'Some error message'
+
+      Facter.warnonce(message)
+      Facter.warnonce(message)
+
+      expect(logger).to have_received(:warn).once.with(message)
+    end
+
+    it 'writes empty message when message is nil' do
+      Facter.warnonce(nil)
+
+      expect(logger).to have_received(:warn).with('')
+    end
+
+    it 'when message is a hash' do
+      Facter.warnonce({ warn: 'message' })
+
+      expect(logger).to have_received(:warn).with('{:warn=>"message"}')
+    end
+
+    it 'returns nil' do
+      result = Facter.warnonce({ warn: 'message' })
+
+      expect(result).to be_nil
+    end
+  end
 end