PR comments, some docs

1 files changed, 12 insertions, 2 deletions

diff --git a/lib/bundler/plugin/events.rb b/lib/bundler/plugin/events.rb
index 3052780b1f..8e94644f2a 100644
--- a/lib/bundler/plugin/events.rb
+++ b/lib/bundler/plugin/events.rb
@@ -4,17 +4,27 @@ module Bundler
   module Plugin
     module Events
       def self.define(const, event)
-        const_set(const.to_sym, event) unless const_defined?(const.to_sym)
+        const = const.to_sym.freeze
+        if const_defined?(const) && const_get(const) != event
+          raise ArgumentError, "Attempting to reassign #{const} to a different value"
+        end
+        const_set(const, event) unless const_defined?(const)
         @events ||= {}
         @events[event] = const
       end
+      private_class_method :define
 
+      # Check if an event has been defined
+      # @param event [String] An event to check
+      # @return [Boolean] A boolean indicating if the event has been defined
       def self.defined_event?(event)
         @events ||= {}
         @events.key?(event)
       end
 
-      # A hook called before any gems install
+      # @!parse
+      #   # A hook called before any gems install
+      #   GEM_BEFORE_INSTALL_ALL = "before-install-all"
       define :GEM_BEFORE_INSTALL_ALL, "before-install-all"
     end
   end