Add SimpleFormBuilder spec

It checks if SimpleForm#input method is callable.
And checks for correct wrapping of a normal text field.

spec/ransack/helpers/simple_form_builder_spec.rb

@@ -0,0 +1,55 @@
+require 'spec_helper'
+
+module Ransack
+  module Helpers
+    describe SimpleFormBuilder do
+
+      router = ActionDispatch::Routing::RouteSet.new
+      router.draw do
+        resources :people, :comments, :notes
+      end
+
+      include router.url_helpers
+
+      # FIXME: figure out a cleaner way to get this behavior
+      before do
+        @controller = ActionView::TestCase::TestController.new
+        @controller.instance_variable_set(:@_routes, router)
+        @controller.class_eval { include router.url_helpers }
+        @controller.view_context_class.class_eval { include router.url_helpers }
+        @s = Person.ransack
+        @controller.view_context.search_simple_form_for(@s) { |f| @f = f }
+      end
+
+      describe "#input (from SimpleForm)" do
+        context "with :name_cont predicate" do
+          subject { @f.input(:name_cont) }
+
+          it "should generate a wrapping div with both label and input inside" do
+            expect(subject).to match(/<div.*?><label.*?<\/label>.*?<input.*?\/>.*?<\/div>/)
+          end
+
+          it "the wrapping div should have class 'q_name_cont'" do
+            expect(subject).to match(/<div.*?class=".*?q_name_cont.*?".*?>/)
+          end
+
+          it "should generate correct label text with predicate from locale files" do
+            expect(subject).to match(/<label.*?>.*?Full Name contains.*?<\/label>/)
+          end
+
+          it "should generate correct input name=\"q[name_cont]\"" do
+            expect(subject).to match(/<input.*?name="q\[name_cont\]".*?\/>/)
+          end
+
+          it "should generate correct input id=\"q_name_cont\"" do
+            expect(subject).to match(/<input.*?id="q_name_cont".*?\/>/)
+          end
+
+          it "should generate correct input type=\"text\"" do
+            expect(subject).to match(/<input.*?type="text".*?\/>/)
+          end
+        end
+      end
+    end
+  end
+end