Fix attribute translator setter

This was simply not working before.

CHANGELOG.md

@@ -12,6 +12,7 @@
 
 #### Fixes
 
+* [#2375](https://github.com/ruby-grape/grape/pull/2375): Fix setter methods for `Grape::Router::AttributeTranslator` - [@Jell](https://github.com/Jell).
 * [#2370](https://github.com/ruby-grape/grape/pull/2370): Remove route_xyz method_missing deprecation - [@ericproulx](https://github.com/ericproulx).
 * [#2372](https://github.com/ruby-grape/grape/pull/2372): Fix `declared` method for hash params with overlapping names - [@jcagarcia](https://github.com/jcagarcia).
 * [#2373](https://github.com/ruby-grape/grape/pull/2373): Fix markdown files for following 1-line format - [@jcagarcia](https://github.com/jcagarcia).

lib/grape/router/attribute_translator.rb

@@ -38,15 +38,15 @@ def to_h
       end
 
       def method_missing(method_name, *args)
-        if setter?(method_name[-1])
-          attributes[method_name[0..]] = *args
+        if setter?(method_name)
+          attributes[method_name.to_s.chomp('=').to_sym] = args.first
         else
           attributes[method_name]
         end
       end
 
       def respond_to_missing?(method_name, _include_private = false)
-        if setter?(method_name[-1])
+        if setter?(method_name)
           true
         else
           @attributes.key?(method_name)
@@ -56,7 +56,7 @@ def respond_to_missing?(method_name, _include_private = false)
       private
 
       def setter?(method_name)
-        method_name[-1] == '='
+        method_name.end_with?('=')
       end
     end
   end

spec/grape/router/attribute_translator_spec.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+describe Grape::Router::AttributeTranslator do
+  (Grape::Router::AttributeTranslator::ROUTE_ATTRIBUTES + Grape::Router::AttributeTranslator::ROUTE_ATTRIBUTES).each do |attribute|
+    describe "##{attribute}" do
+      it "returns value from #{attribute} key if present" do
+        translator = described_class.new(attribute => 'value')
+        expect(translator.public_send(attribute)).to eq('value')
+      end
+
+      it "returns nil from #{attribute} key if missing" do
+        translator = described_class.new
+        expect(translator.public_send(attribute)).to be_nil
+      end
+    end
+
+    describe "##{attribute}=" do
+      it "sets value for #{attribute}", :aggregate_failures do
+        translator = described_class.new(attribute => 'value')
+        expect do
+          translator.public_send("#{attribute}=", 'new_value')
+        end.to change(translator, attribute).from('value').to('new_value')
+      end
+    end
+  end
+end