Merge pull request #27792 from tjoyal/sandbox-tagged-logging

TaggedLogging to return a new logger instance

activesupport/CHANGELOG.md

@@ -1,3 +1,8 @@
+*   Changed `ActiveSupport::TaggedLogging.new` to return a new logger instance instead
+    of mutating the one received as parameter.
+
+    *Thierry Joyal*
+
 *   Define `unfreeze_time` as an alias of `travel_back` in `ActiveSupport::Testing::TimeHelpers`.
 
     The alias is provided for symmetry with `freeze_time`.

activesupport/lib/active_support/tagged_logging.rb

@@ -61,8 +61,15 @@ module ActiveSupport
     end
 
     def self.new(logger)
-      # Ensure we set a default formatter so we aren't extending nil!
-      logger.formatter ||= ActiveSupport::Logger::SimpleFormatter.new
+      logger = logger.dup
+
+      if logger.formatter
+        logger.formatter = logger.formatter.dup
+      else
+        # Ensure we set a default formatter so we aren't extending nil!
+        logger.formatter = ActiveSupport::Logger::SimpleFormatter.new
+      end
+
       logger.formatter.extend Formatter
       logger.extend(self)
     end

activesupport/test/tagged_logging_test.rb

@@ -19,9 +19,10 @@ class TaggedLoggingTest < ActiveSupport::TestCase
   test "sets logger.formatter if missing and extends it with a tagging API" do
     logger = Logger.new(StringIO.new)
     assert_nil logger.formatter
-    ActiveSupport::TaggedLogging.new(logger)
-    assert_not_nil logger.formatter
-    assert_respond_to logger.formatter, :tagged
+
+    other_logger = ActiveSupport::TaggedLogging.new(logger)
+    assert_not_nil other_logger.formatter
+    assert_respond_to other_logger.formatter, :tagged
   end
 
   test "tagged once" do
@@ -83,16 +84,28 @@ class TaggedLoggingTest < ActiveSupport::TestCase
   end
 
   test "keeps each tag in their own instance" do
-    @other_output = StringIO.new
-    @other_logger = ActiveSupport::TaggedLogging.new(MyLogger.new(@other_output))
+    other_output = StringIO.new
+    other_logger = ActiveSupport::TaggedLogging.new(MyLogger.new(other_output))
     @logger.tagged("OMG") do
-      @other_logger.tagged("BCX") do
+      other_logger.tagged("BCX") do
         @logger.info "Cool story"
-        @other_logger.info "Funky time"
+        other_logger.info "Funky time"
       end
     end
     assert_equal "[OMG] Cool story\n", @output.string
-    assert_equal "[BCX] Funky time\n", @other_output.string
+    assert_equal "[BCX] Funky time\n", other_output.string
+  end
+
+  test "does not share the same formatter instance of the original logger" do
+    other_logger = ActiveSupport::TaggedLogging.new(@logger)
+
+    @logger.tagged("OMG") do
+      other_logger.tagged("BCX") do
+        @logger.info "Cool story"
+        other_logger.info "Funky time"
+      end
+    end
+    assert_equal "[OMG] Cool story\n[BCX] Funky time\n", @output.string
   end
 
   test "cleans up the taggings on flush" do