Added a custom validations spec.

README.md

@@ -980,7 +980,7 @@ end
 class AlphaNumeric < Grape::Validations::Base
   def validate_param!(attr_name, params)
     unless params[attr_name] =~ /^[[:alnum:]]+$/
-      raise Grape::Exceptions::Validation, params: [@scope.full_name(attr_name)], message: "must consist of alpha-numeric characters"
+      fail Grape::Exceptions::Validation, params: [@scope.full_name(attr_name)], message: "must consist of alpha-numeric characters"
     end
   end
 end
@@ -998,7 +998,7 @@ You can also create custom classes that take parameters.
 class Length < Grape::Validations::Base
   def validate_param!(attr_name, params)
     unless params[attr_name].length <= @option
-      raise Grape::Exceptions::Validation, params: [@scope.full_name(attr_name)], message: "must be at the most #{@option} characters long"
+      fail Grape::Exceptions::Validation, params: [@scope.full_name(attr_name)], message: "must be at the most #{@option} characters long"
     end
   end
 end

spec/grape/api/custom_validations_spec.rb

@@ -0,0 +1,47 @@
+require 'spec_helper'
+
+describe Grape::Validations do
+  before do
+    class DefaultLength < Grape::Validations::Base
+      def validate_param!(attr_name, params)
+        @option = params[:max].to_i if params.key?(:max)
+        unless params[attr_name].length <= @option
+          fail Grape::Exceptions::Validation, params: [@scope.full_name(attr_name)], message: "must be at the most #{@option} characters long"
+        end
+      end
+    end
+  end
+
+  subject do
+    Class.new(Grape::API) do
+      params do
+        requires :text, default_length: 140
+      end
+      get do
+        'bacon'
+      end
+    end
+  end
+
+  def app
+    subject
+  end
+
+  context 'using a custom length validator' do
+    it 'under 140 characters' do
+      get '/', text: 'abc'
+      expect(last_response.status).to eq 200
+      expect(last_response.body).to eq 'bacon'
+    end
+    it 'over 140 characters' do
+      get '/', text: 'a' * 141
+      expect(last_response.status).to eq 400
+      expect(last_response.body).to eq 'text must be at the most 140 characters long'
+    end
+    it 'specified in the query string' do
+      get '/', text: 'a' * 141, max: 141
+      expect(last_response.status).to eq 200
+      expect(last_response.body).to eq 'bacon'
+    end
+  end
+end