Fix access to the final page of todos

The todos page limit is 20, and both that and a user's pending todo count are
integers. Using integer division means that the result's floor will be taken,
defeating the point of the later call to `#ceil`.

So we need to convert one side of the division to a float first, otherwise the
last page won't be treated as available.

app/controllers/dashboard/todos_controller.rb

@@ -76,7 +76,7 @@ class Dashboard::TodosController < Dashboard::ApplicationController
   def redirect_out_of_range(todos)
     total_pages =
       if todo_params.except(:sort, :page).empty?
-        (current_user.todos_pending_count / todos.limit_value).ceil
+        (current_user.todos_pending_count.to_f / todos.limit_value).ceil
       else
         todos.total_pages
       end

changelogs/unreleased/fix-todos-last-page.yml

@@ -0,0 +1,5 @@
+---
+title: Fix access to the final page of todos
+merge_request:
+author:
+type: fixed

spec/controllers/dashboard/todos_controller_spec.rb

@@ -44,11 +44,11 @@ describe Dashboard::TodosController do
 
     context 'when using pagination' do
       let(:last_page) { user.todos.page.total_pages }
-      let!(:issues) { create_list(:issue, 2, project: project, assignees: [user]) }
+      let!(:issues) { create_list(:issue, 3, project: project, assignees: [user]) }
 
       before do
         issues.each { |issue| todo_service.new_issue(issue, user) }
-        allow(Kaminari.config).to receive(:default_per_page).and_return(1)
+        allow(Kaminari.config).to receive(:default_per_page).and_return(2)
       end
 
       it 'redirects to last_page if page number is larger than number of pages' do