Fixed issue when assigning no weight

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/18374

app/assets/javascripts/weight_select.js.coffee

@@ -13,7 +13,7 @@ class @WeightSelect
       updateWeight = (selected) ->
         data = {}
         data[abilityName] = {}
-        data[abilityName].weight = selected
+        data[abilityName].weight = if selected? then selected else null
         $loading
           .fadeIn()
         $dropdown.trigger('loading.gl.dropdown')
@@ -27,7 +27,10 @@ class @WeightSelect
           $loading.fadeOut()
           $selectbox.hide()
 
-          $value.html(data.weight)
+          if data.weight?
+            $value.html(data.weight)
+          else
+            $value.html('None')
           $sidebarCollapsedValue.html(data.weight)
 
       $dropdown.glDropdown(
@@ -38,7 +41,8 @@ class @WeightSelect
           # display:block overrides the hide-collapse rule
           $value.css('display', '')
         id: (obj, el) ->
-          $(el).data "id"
+          if not $(el).data("none")?
+            $(el).data "id"
         clicked: (selected) ->
           if $(dropdown).is ".js-filter-submit"
             $(dropdown).parents('form').submit()

app/views/shared/issuable/_sidebar.html.haml

@@ -151,7 +151,7 @@
               %ul
                 - Issue.weight_options.select{|weight| weight != "Everything" && weight != "Any Weight"}.each do |weight|
                   %li
-                    %a{href: "#", data: { id: weight }, class: ("is-active" if params[:weight] == weight.to_s)}
+                    %a{href: "#", data: { id: weight, none: ("true" if weight == Issue::WEIGHT_NONE) }, class: ("is-active" if params[:weight] == weight.to_s)}
                       = weight
 
       = render "shared/issuable/participants", participants: issuable.participants(current_user)

spec/features/issues/issue_sidebar_spec.rb

@@ -73,6 +73,35 @@ feature 'Issue Sidebar', feature: true do
     end
   end
 
+  context 'updating weight', js: true do
+    before do
+      project.team << [user, :master]
+      visit_issue(project, issue)
+    end
+
+    it 'should update weight in sidebar to 1' do
+      page.within '.weight' do
+        click_link 'Edit'
+        click_link '1'
+
+        page.within '.value' do
+          expect(page).to have_content '1'
+        end
+      end
+    end
+
+    it 'should update weight in sidebar to no weight' do
+      page.within '.weight' do
+        click_link 'Edit'
+        click_link 'No Weight'
+
+        page.within '.value' do
+          expect(page).to have_content 'None'
+        end
+      end
+    end
+  end
+
   def visit_issue(project, issue)
     visit namespace_project_issue_path(project.namespace, project, issue)
   end