Return a Duration instead of a Time for the ETA (#430)

app/helpers/maintenance_tasks/tasks_helper.rb

@@ -63,20 +63,6 @@ def status_tag(status)
       tag.span(status.capitalize, class: ["tag"] + STATUS_COLOURS.fetch(status))
     end
 
-    # Returns the distance between now and the Run's expected completion time,
-    # if the Run has an estimated_completion_time.
-    #
-    # @param run [MaintenanceTasks::Run] the Run for which the estimated time to
-    #   completion is being calculated.
-    # return [String, nil] the distance in words, or nil if the Run has no
-    #   estimated completion time.
-    def estimated_time_to_completion(run)
-      estimated_completion_time = run.estimated_completion_time
-      if estimated_completion_time.present?
-        time_ago_in_words(estimated_completion_time)
-      end
-    end
-
     # Reports the approximate elapsed time a Run has been processed so far based
     # on the Run's time running attribute.
     #

app/models/maintenance_tasks/run.rb

@@ -151,19 +151,19 @@ def active?
       ACTIVE_STATUSES.include?(status.to_sym)
     end
 
-    # Returns the estimated time the task will finish based on the the number of
-    # ticks left and the average time needed to process a tick.
-    # Returns nil if the Run is completed, or if the tick_count or tick_total is
-    # zero.
+    # Returns the duration left for the Run to finish based on the number of
+    # ticks left and the average time needed to process a tick. Returns nil if
+    # the Run is completed, or if tick_count or tick_total is zero.
     #
-    # @return [Time] the estimated time the Run will finish.
-    def estimated_completion_time
+    # @return [ActiveSupport::Duration] the estimated duration left for the Run
+    #   to finish.
+    def time_to_completion
       return if completed? || tick_count == 0 || tick_total.to_i == 0
 
       processed_per_second = (tick_count.to_f / time_running)
       ticks_left = (tick_total - tick_count)
       seconds_to_finished = ticks_left / processed_per_second
-      Time.now + seconds_to_finished
+      seconds_to_finished.seconds
     end
 
     # Cancels a Run.

app/views/maintenance_tasks/runs/info/_paused.html.erb

@@ -1,7 +1,7 @@
 <p>
   Ran for <%= time_running_in_words run  %> until paused,
-  <% if run.estimated_completion_time %>
-    <%= estimated_time_to_completion(run) %> remaining.
+  <% if (time_to_completion = run.time_to_completion) %>
+    <%= distance_of_time_in_words(time_to_completion) %> remaining.
   <% else %>
     processed <%= pluralize run.tick_count, 'item' %> so far.
   <% end %>

app/views/maintenance_tasks/runs/info/_running.html.erb

@@ -1,5 +1,5 @@
 <p>
-  <% if run.estimated_completion_time %>
-    <%= estimated_time_to_completion(run).capitalize %> remaining.
+  <% if (time_to_completion = run.time_to_completion) %>
+    <%= distance_of_time_in_words(time_to_completion).capitalize %> remaining.
   <% end %>
 </p>

test/helpers/maintenance_tasks/tasks_helper_test.rb

@@ -54,15 +54,6 @@ class TasksHelperTest < ActionView::TestCase
       assert_equal expected, status_tag("pausing")
     end
 
-    test "#estimated_time_to_completion returns the Run's estimated_completion_time in words" do
-      @run.expects(estimated_completion_time: Time.now + 2.minutes)
-      assert_equal "2 minutes", estimated_time_to_completion(@run)
-    end
-
-    test "#estimated_time_to_completion returns nil if the Run has no estimated_completion_time" do
-      assert_nil estimated_time_to_completion(@run)
-    end
-
     test "#time_running_in_words reports the approximate time running of the given Run" do
       @run.time_running = 182.5
       assert_equal "3 minutes", time_running_in_words(@run)

test/models/maintenance_tasks/run_test.rb

@@ -158,51 +158,46 @@ class RunTest < ActiveSupport::TestCase
       end
     end
 
-    test "#estimated_completion_time returns nil if the run is completed" do
+    test "#time_to_completion returns nil if the run is completed" do
       run = Run.new(
         task_name: "Maintenance::UpdatePostsTask",
         status: :succeeded
       )
 
-      assert_nil run.estimated_completion_time
+      assert_nil run.time_to_completion
     end
 
-    test "#estimated_completion_time returns nil if tick_count is 0" do
+    test "#time_to_completion returns nil if tick_count is 0" do
       run = Run.new(
         task_name: "Maintenance::UpdatePostsTask",
         status: :running,
         tick_count: 0,
         tick_total: 10
       )
 
-      assert_nil run.estimated_completion_time
+      assert_nil run.time_to_completion
     end
 
-    test "#estimated_completion_time returns nil if no tick_total" do
+    test "#time_to_completion returns nil if no tick_total" do
       run = Run.new(
         task_name: "Maintenance::UpdatePostsTask",
         status: :running,
         tick_count: 1
       )
 
-      assert_nil run.estimated_completion_time
+      assert_nil run.time_to_completion
     end
 
-    test "#estimated_completion_time returns estimated completion time based on average time elapsed per tick" do
-      started_at = Time.utc(2020, 1, 9, 9, 41, 44)
-      travel_to started_at + 9.seconds
-
+    test "#time_to_completion returns estimated duration until completion based on average time elapsed per tick" do
       run = Run.new(
         task_name: "Maintenance::UpdatePostsTask",
-        started_at: started_at,
         status: :running,
         tick_count: 9,
         tick_total: 10,
         time_running: 9,
       )
 
-      expected_completion_time = Time.utc(2020, 1, 9, 9, 41, 54)
-      assert_equal expected_completion_time, run.estimated_completion_time
+      assert_equal 1.second, run.time_to_completion
     end
 
     test "#cancel transitions the Run to cancelling if not paused" do