Validate configuration better

encoded_id-rails.gemspec

@@ -32,7 +32,7 @@ Gem::Specification.new do |spec|
   # Uncomment to register a new dependency of your gem
   spec.add_dependency "activesupport", ">= 6.0", "< 8.0"
   spec.add_dependency "activerecord", ">= 6.0", "< 8.0"
-  spec.add_dependency "encoded_id", "~> 1.0.0.rc1"
+  spec.add_dependency "encoded_id", "~> 1.0.0.rc2"
 
   # For more information and examples about making a new gem, check out our
   # guide at: https://bundler.io/guides/creating_gem.html

lib/encoded_id/rails/configuration.rb

@@ -4,15 +4,9 @@ module EncodedId
   module Rails
     # Configuration class for initializer
     class Configuration
-      attr_accessor :salt,
-        :character_group_size,
-        :group_separator,
-        :alphabet,
-        :id_length,
-        :slug_value_method_name,
-        :slugged_id_separator,
-        :annotation_method_name, # Set to nil to disable annotated IDs
-        :annotated_id_separator
+      attr_accessor :salt, :character_group_size, :alphabet, :id_length
+      attr_accessor :slug_value_method_name, :annotation_method_name
+      attr_reader :group_separator, :slugged_id_separator, :annotated_id_separator
 
       def initialize
         @character_group_size = 4
@@ -24,6 +18,33 @@ def initialize
         @annotation_method_name = :annotation_for_encoded_id
         @annotated_id_separator = "_"
       end
+
+      # Perform validation vs alphabet on these assignments
+
+      def group_separator=(value)
+        unless valid_separator?(value, alphabet)
+          raise ArgumentError, "Group separator characters must not be part of the alphabet"
+        end
+        @group_separator = value
+      end
+
+      def slugged_id_separator=(value)
+        if value.blank? || value == group_separator || !valid_separator?(value, alphabet)
+          raise ArgumentError, "Slugged ID separator characters must not be part of the alphabet or the same as the group separator"
+        end
+        @slugged_id_separator = value
+      end
+
+      def annotated_id_separator=(value)
+        if value.blank? || value == group_separator || !valid_separator?(value, alphabet)
+          raise ArgumentError, "Annotated ID separator characters must not be part of the alphabet or the same as the group separator"
+        end
+        @annotated_id_separator = value
+      end
+
+      def valid_separator?(separator, characters)
+        separator.chars.none? { |v| characters.include?(v) }
+      end
     end
   end
 end

lib/generators/encoded_id/rails/templates/encoded_id.rb

@@ -41,4 +41,30 @@
   # Default: 8
   #
   # config.id_length = 8
+
+  # The name of the method that returns the value to be used in the slug.
+  #
+  # Default: :name_for_encoded_id_slug
+  #
+  # config.slug_value_method_name = :name_for_encoded_id_slug
+
+  # The separator used between the slug and the encoded ID.
+  # `nil` disables grouping.
+  #
+  # Default: "--"
+  #
+  # config.slugged_id_separator = "--"
+
+  # The name of the method that returns the annotation to be used in the annotated ID.
+  #
+  # Default: :annotation_for_encoded_id
+  #
+  # config.annotation_method_name = :annotation_for_encoded_id
+
+  # The separator used between the annotation and the encoded ID.
+  # `nil` disables annotation.
+  #
+  # Default: "_"
+  #
+  # config.annotated_id_separator = "_"
 end

test/encoded_id/test_rails.rb

@@ -14,6 +14,28 @@ def setup
     EncodedId::Rails.configuration.slug_value_method_name = :custom_slug_method
   end
 
+  def test_configuration_prevents_invalid_group_separator
+    assert_raises ArgumentError do
+      EncodedId::Rails.configuration.group_separator = "a"
+    end
+  end
+
+  def test_configuration_prevents_invalid_slugged_id_separator
+    assert_raises ArgumentError do
+      EncodedId::Rails.configuration.slugged_id_separator = "a"
+    end
+    EncodedId::Rails.configuration.group_separator = "-"
+    assert_raises ArgumentError do
+      EncodedId::Rails.configuration.slugged_id_separator = "-"
+    end
+  end
+
+  def test_configuration_prevents_invalid_annotated_id_separator
+    assert_raises ArgumentError do
+      EncodedId::Rails.configuration.annotated_id_separator = "a"
+    end
+  end
+
   def test_find_by_encoded_id_gets_model_given_encoded_id
     assert_equal model, MyModel.find_by_encoded_id(model.encoded_id)
   end