fix wiki page creation for students

test plan:
* create a course
* create a page, allowing "Teachers and students"
 to edit the page
* as a student, should be able to edit the page,
 but should not be able to link to new pages in
 the wiki sidebar

* edit the settings to allow "Teachers and Students"
 to "create, rename and edit course wiki pages"
* as a student, should be able to link to new pages
* should also be able to follow the links and
 create the new pages there

closes #CNVS-18825

Change-Id: If272218522e36310edf95fe77fe3b8af03456725
Reviewed-on: https://gerrit.instructure.com/49678
Tested-by: Jenkins
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
QA-Review: Jahnavi Yetukuri <jyetukuri@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>

app/controllers/wiki_pages_api_controller.rb

@@ -504,7 +504,7 @@ class WikiPagesApiController < ApplicationController
         @set_front_page = true
         @set_as_front_page = true
       else
-        @page.workflow_state = 'unpublished'
+        @page.workflow_state = @wiki.grants_right?(@current_user, session, :manage) ? 'unpublished' : 'active'
       end
     end
   end

app/views/shared/_wiki_sidebar.html.erb

@@ -31,15 +31,17 @@
                 <% end %>
               <% end %>
             </ul>
-            <%= link_to t('links.new_page', "Link to a New Page"), polymorphic_url([@context, :wiki_page], action: :new), :id => 'new_page_link', :class => "add" %>
-            <form id="new_page_drop_down" style="display:none; margin: 5px;">
-              <div class="row-fluid">
-                <label for="new_page_name"><%= t('new_page_name', %{What would you like to call the new page?}) %></label><br />
-                <input type="text" name="new_page_name" id="new_page_name" class="span12">
-                <input type="hidden" name="new_page_url_prefix" value="<%= polymorphic_path([@context, :wiki_pages]) %>" id="new_page_url_prefix" />
-                <button id="new_page_submit" class="btn btn-small" type="submit"><%= t('buttons.insert_link', %{Insert Link}) %></button>
-              </div>
-            </form>
+            <% if can_do(@wiki, @current_user, :create_page) %>
+              <%= link_to t('links.new_page', "Link to a New Page"), polymorphic_url([@context, :wiki_page], action: :new), :id => 'new_page_link', :class => "add" %>
+              <form id="new_page_drop_down" style="display:none; margin: 5px;">
+                <div class="row-fluid">
+                  <label for="new_page_name"><%= t('new_page_name', %{What would you like to call the new page?}) %></label><br />
+                  <input type="text" name="new_page_name" id="new_page_name" class="span12">
+                  <input type="hidden" name="new_page_url_prefix" value="<%= polymorphic_path([@context, :wiki_pages]) %>" id="new_page_url_prefix" />
+                  <button id="new_page_submit" class="btn btn-small" type="submit"><%= t('buttons.insert_link', %{Insert Link}) %></button>
+                </div>
+              </form>
+            <% end %>
         </div>
       </div>
       <% end %>

spec/selenium/student_wiki_and_tiny_spec.rb

@@ -70,6 +70,39 @@ describe "Wiki pages and Tiny WYSIWYG editor" do
 
       expect(f('a.edit-wiki')).to be_displayed
     end
+    
+    it "should allow students to create new pages if enabled" do
+      @course.default_wiki_editing_roles = "teachers,students"
+      @course.save!
+
+      get "/courses/#{@course.id}/pages"
+      wait_for_ajax_requests
+      f('.new_page').click
+      f("#title").send_keys("new page")
+
+      expect_new_page_load { f('form.edit-form button.submit').click }
+      new_page = @course.wiki.wiki_pages.last
+      expect(new_page).to be_published
+    end
+
+    it "should not allow students to add links to new pages unless they can create pages" do
+      create_wiki_page("test_page", false, "public")
+      get "/courses/#{@course.id}/pages/test_page/edit"
+      wait_for_ajax_requests
+
+      expect(f('#new_page_link')).to be_nil
+
+      @course.default_wiki_editing_roles = "teachers,students"
+      @course.save!
+
+      get "/courses/#{@course.id}/pages/somenewpage/edit" # page that doesn't exist
+      wait_for_ajax_requests
+
+      expect(f('#new_page_link')).to_not be_nil
+      expect_new_page_load { f('form.edit-form button.submit').click }
+      new_page = @course.wiki.wiki_pages.last
+      expect(new_page).to be_published
+    end
 
     it "should notify users when wiki page gets changed" do
       set_notification_policy