Make sure that link_to_{previous,next}_page work for every view adapter

kaminari-core/test/fake_app/rails_app.rb

@@ -35,6 +35,8 @@ class UsersController < ApplicationController
     @users = User.page params[:page]
     render inline: <<-ERB
 <%= @users.map(&:name).join("\n") %>
+<%= link_to_previous_page @users, 'previous page', class: 'prev' %>
+<%= link_to_next_page @users, 'next page', class: 'next' %>
 <%= paginate @users %>
 <div class="info"><%= page_entries_info @users %></div>
 ERB

kaminari-core/test/requests/navigation_test.rb

@@ -18,6 +18,9 @@ class NavigationTest < Test::Unit::TestCase
   test 'navigating by pagination links' do
     visit '/users'
 
+    assert page.has_no_content? 'previous page'
+    assert page.has_content? 'next page'
+
     within 'nav.pagination' do
       within 'span.page.current' do
         assert page.has_content? '1'
@@ -27,6 +30,9 @@ class NavigationTest < Test::Unit::TestCase
       end
     end
 
+    assert page.has_content? 'previous page'
+    assert page.has_content? 'next page'
+
     within 'nav.pagination' do
       within 'span.page.current' do
         assert page.has_content? '2'
@@ -36,6 +42,9 @@ class NavigationTest < Test::Unit::TestCase
       end
     end
 
+    assert page.has_content? 'previous page'
+    assert page.has_no_content? 'next page'
+
     within 'nav.pagination' do
       within 'span.page.current' do
         assert page.has_content? '4'
@@ -45,6 +54,9 @@ class NavigationTest < Test::Unit::TestCase
       end
     end
 
+    assert page.has_content? 'previous page'
+    assert page.has_content? 'next page'
+
     within 'nav.pagination' do
       within 'span.page.current' do
         assert page.has_content? '3'