ErrorReporter#debug to swallow in production but raise in development

It's a common useful pattern for situation where something isn't
supposed to fail, but if it does we can recover from it.

So in such situation you don't want such failure to be swallowed
in development or test, as it's likely a bug, but do not want to
fail a request if it happens in production.

In other words, it behaves like `#record` in development and test
environments, and like `handle` in production.

Fix: rails#49638
Fix: rails#49339

Co-Authored-By: Andrew Novoselac <[email protected]>
Co-Authored-By: Dustin Brown <[email protected]>

activesupport/lib/active_support/error_reporter.rb

@@ -26,12 +26,14 @@ module ActiveSupport
   class ErrorReporter
     SEVERITIES = %i(error warning info)
     DEFAULT_SOURCE = "application"
+    DEFAULT_RESCUE = [StandardError].freeze
 
-    attr_accessor :logger
+    attr_accessor :logger, :debug_mode
 
     def initialize(*subscribers, logger: nil)
       @subscribers = subscribers.flatten
       @logger = logger
+      @debug_mode = false
     end
 
     # Evaluates the given block, reporting and swallowing any unhandled error.
@@ -72,7 +74,7 @@ def initialize(*subscribers, logger: nil)
     #   source of the error. Subscribers can use this value to ignore certain
     #   errors. Defaults to <tt>"application"</tt>.
     def handle(*error_classes, severity: :warning, context: {}, fallback: nil, source: DEFAULT_SOURCE)
-      error_classes = [StandardError] if error_classes.blank?
+      error_classes = DEFAULT_RESCUE if error_classes.empty?
       yield
     rescue *error_classes => error
       report(error, handled: true, severity: severity, context: context, source: source)
@@ -108,13 +110,31 @@ def handle(*error_classes, severity: :warning, context: {}, fallback: nil, sourc
     #   source of the error. Subscribers can use this value to ignore certain
     #   errors. Defaults to <tt>"application"</tt>.
     def record(*error_classes, severity: :error, context: {}, source: DEFAULT_SOURCE)
-      error_classes = [StandardError] if error_classes.blank?
+      error_classes = DEFAULT_RESCUE if error_classes.empty?
       yield
     rescue *error_classes => error
       report(error, handled: false, severity: severity, context: context, source: source)
       raise
     end
 
+    # Evaluates the given block, reporting any unhandled error.
+    # The error is then either re-raised if +config.consider_all_requests_local == true+
+    # or otherwise swallowed.
+    #
+    # In other words in behaves like +record+ in development and test, and like +handle+
+    # in production.
+    def debug(*error_classes, severity: :warning, context: {}, fallback: nil, source: DEFAULT_SOURCE)
+      error_classes = DEFAULT_RESCUE if error_classes.empty?
+      yield
+    rescue *error_classes => error
+      report(error, handled: true, severity: severity, context: context, source: source)
+      if @debug_mode
+        raise
+      else
+        fallback.call if fallback
+      end
+    end
+
     # Register a new error subscriber. The subscriber must respond to
     #
     #   report(Exception, handled: Boolean, severity: (:error OR :warning OR :info), context: Hash, source: String)

activesupport/test/error_reporter_test.rb

@@ -168,6 +168,23 @@ class ErrorReporterTest < ActiveSupport::TestCase
     assert_equal 4, result
   end
 
+  test "#debug swallows errors by default" do
+    result = @reporter.debug(fallback: -> { 2 + 2 }) do
+      raise StandardError
+    end
+    assert_equal 4, result
+  end
+
+  test "#debug re-raise errors in development and test" do
+    @reporter.debug_mode = true
+    error = assert_raises RumtimeError do
+      @reporter.debug(fallback: -> { nil }) do
+        raise "Oops"
+      end
+    end
+    assert_includes error.message, "Oops"
+  end
+
   test "can have multiple subscribers" do
     second_subscriber = ErrorSubscriber.new
     @reporter.subscribe(second_subscriber)

railties/lib/rails/application/bootstrap.rb

@@ -61,8 +61,12 @@ module Bootstrap
           broadcast_logger.formatter = Rails.logger.formatter
           Rails.logger = broadcast_logger
         end
+      end
 
-        unless config.consider_all_requests_local
+      initializer :initialize_error_reporter, group: :all do
+        if config.consider_all_requests_local
+          Rails.error.debug_mode = true
+        else
           Rails.error.logger = Rails.logger
         end
       end