Included Guilherme Victal works on overduedate

See https://github.com/freitass/todo.txt-vim/pull/45

test/tc_mark_as_done.vim

@@ -0,0 +1,36 @@
+let s:here = expand('<sfile>:p:h')
+let s:context = todo#txt#__context__()
+let s:context['data'] = s:here . '/tc_mark_as_done.todo.txt'
+let s:tc = unittest#testcase#new('Mark As Done', s:context)
+
+let s:TODAY = strftime("%Y-%m-%d")
+
+let s:FIRST_TASK_DONE = [
+      \ 'x ' . s:TODAY . ' first task to be marked as done',
+      \ 'second task to be marked as done',
+      \ '2015-05-20 third task to be marked as done',
+      \ ]
+
+let s:ALL_TASKS_DONE = [
+      \ 'x ' . s:TODAY . ' first task to be marked as done',
+      \ 'x ' . s:TODAY . ' second task to be marked as done',
+      \ 'x ' . s:TODAY . ' 2015-05-20 third task to be marked as done',
+      \ ]
+
+function! s:tc.test_mark_as_done()
+  call self.data.goto('lorem_ipsum')
+  call todo#txt#mark_as_done()
+  call self.assert_equal(s:FIRST_TASK_DONE, self.data.get('lorem_ipsum'))
+endfunction
+
+function! s:tc.test_mark_range_as_done()
+  call self.data.execute('call todo#txt#mark_as_done()', 'lorem_ipsum')
+  call self.assert_equal(s:ALL_TASKS_DONE, self.data.get('lorem_ipsum'))
+endfunction
+
+function! s:tc.test_mark_selection_as_done()
+  call self.data.visual_execute('call todo#txt#mark_as_done()', 'lorem_ipsum')
+  call self.assert_equal(s:ALL_TASKS_DONE, self.data.get('lorem_ipsum'))
+endfunction
+
+unlet s:tc