Event notification hooks

lib/evil_events/core/events.rb

@@ -21,6 +21,11 @@ module Events
     require_relative 'events/event_extensions/class_signature'
     require_relative 'events/event_extensions/class_signature/signature'
     require_relative 'events/event_extensions/class_signature/equalizer'
+    require_relative 'events/event_extensions/hookable'
+    require_relative 'events/event_extensions/hookable/abstract_hook'
+    require_relative 'events/event_extensions/hookable/after_hook'
+    require_relative 'events/event_extensions/hookable/before_hook'
+    require_relative 'events/event_extensions/hookable/on_error_hook'
     require_relative 'events/abstract_event'
     require_relative 'events/manager'
     require_relative 'events/manager/notifier'

lib/evil_events/core/events/abstract_event.rb

@@ -23,6 +23,8 @@ class AbstractEvent
     include EventExtensions::MetadataExtendable
     # @sicne 0.2.0
     include EventExtensions::ClassSignature
+    # @since 0.3.0
+    include EventExtensions::Hookable
     # @since 0.1.0
     extend EvilEvents::Shared::CombinedContext::Mixin
 

lib/evil_events/core/events/event_extensions/hookable.rb

@@ -0,0 +1,91 @@
+# frozen_string_literal: true
+
+module EvilEvents::Core::Events::EventExtensions
+  # @api private
+  # @since 0.3.0
+  module Hookable
+    class << self
+      # @param base_class [Class]
+      #
+      # @since 0.3.0
+      def included(base_class)
+        base_class.extend(ClassMethods)
+      end
+    end
+
+    # @api private
+    # @since 0.3.0
+    def __call_on_error_hooks__
+      self.class.__on_error_hooks__.each do |hook|
+        hook.call(self)
+      end
+    end
+
+    # @api private
+    # @since 0.3.0
+    def __call_before_hooks__
+      self.class.__before_hooks__.each do |hook|
+        hook.call(self)
+      end
+    end
+
+    # @api private
+    # @since 0.3.0
+    def __call_after_hooks__
+      self.class.__after_hooks__.each do |hook|
+        hook.call(self)
+      end
+    end
+
+    # @since 0.3.0
+    module ClassMethods
+      # @param hook [#call]
+      #
+      # @api public
+      # @since 0.3.0
+      def before_emit(hook)
+        __before_hooks__ << BeforeHook.new(hook)
+      end
+
+      # @param hook [#call]
+      #
+      # @api public
+      # @since 0.3.0
+      def after_emit(hook)
+        __after_hooks__ << AfterHook.new(hook)
+      end
+
+      # @param hook [#call]
+      #
+      # @api public
+      # @since 0.3.0
+      def on_error(hook)
+        __on_error_hooks__ << OnErrorHook.new(hook)
+      end
+
+      # @return [Concurrent::Array<BeforeHook>]
+      #
+      # @api private
+      # @since 0.3.0
+      def __before_hooks__
+        @__before_hooks__ ||= Concurrent::Array.new
+      end
+
+      # @return [Concurrent::Array<AfterHook>]
+      #
+      # @api private
+      # @since 0.3.0
+      def __after_hooks__
+        @__after_hooks__ ||= Concurrent::Array.new
+      end
+
+      # @return [Concurrent::Array<OnErrorHook>]
+      #
+      # @api private
+      # @since 0.3.0
+      def __on_error_hooks__
+        @__on_error_hooks__ ||= Concurrent::Array.new
+      end
+    end
+  end
+end

lib/evil_events/core/events/event_extensions/hookable/abstract_hook.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+module EvilEvents::Core::Events::EventExtensions::Hookable
+  # @api private
+  # @since 0.3.0
+  class AbstractHook
+    # @return [#call]
+    #
+    # @since 0.3.0
+    attr_reader :callable
+
+    # @param callable [#call]
+    #
+    # @since 0.3.0
+    def initialize(callable)
+      @callable = callable
+    end
+
+    # @param event [EvilEvents::Core::Events::AbstractEvent]
+    # @return void
+    #
+    # @since 0.3.0
+    def call(event)
+      callable.call(event)
+    end
+  end
+end

lib/evil_events/core/events/event_extensions/hookable/after_hook.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+module EvilEvents::Core::Events::EventExtensions::Hookable
+  # @api private
+  # @since 0.3.0
+  AfterHook = Class.new(AbstractHook)
+end

lib/evil_events/core/events/event_extensions/hookable/before_hook.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+module EvilEvents::Core::Events::EventExtensions::Hookable
+  # @api private
+  # @since 0.3.0
+  BeforeHook = Class.new(AbstractHook)
+end

lib/evil_events/core/events/event_extensions/hookable/on_error_hook.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+module EvilEvents::Core::Events::EventExtensions::Hookable
+  # @api private
+  # @since 0.3.0
+  OnErrorHook = Class.new(AbstractHook)
+end

lib/evil_events/core/events/manager/notifier.rb

@@ -47,9 +47,16 @@ def run(manager, event)
 
         manager.subscribers.each do |subscriber|
           begin
+            event.__call_before_hooks__
+
             subscriber.notify(event)
+
+            event.__call_after_hooks__
+
             log_activity(event, subscriber, :successful)
           rescue StandardError => error
+            event.__call_on_error_hooks__
+
             errors_stack << error
             log_activity(event, subscriber, :failed)
           end

spec/integration/event_creation_spec.rb

@@ -74,6 +74,11 @@ def process_event(event); end
           # method that will be invoked on observers by default (delegator: option)
           default_delegator :process_event
 
+          # emition hooks
+          before_emit -> {}
+          after_emit -> {}
+          on_error -> {}
+
           # payload keys
           payload :user_id,  EvilEvents::Types::Strict::Int
           payload :utm_link, EvilEvents::Types::Strict::String
@@ -118,6 +123,11 @@ class UserRegistered < EvilEvents::Event['user_registered']
           # method that will be invoked on observers by default (delegator: option)
           default_delegator :process_event
 
+          # emition hooks
+          before_emit -> {}
+          after_emit -> {}
+          on_error -> {}
+
           # payload keys
           payload :user_id,  EvilEvents::Types::Strict::Int
           payload :utm_link, EvilEvents::Types::Strict::String

spec/units/evil_events/core/system/mock_spec.rb

@@ -25,7 +25,7 @@
         mocked_method_params = mocked_method_object.parameters
 
         # 2. mocked method signature equals to original method signature
-        expect(method_params).to match(method_params)
+        expect(mocked_method_params).to match(method_params)
       end
     end
   end