Add tests

apps/transport/lib/transport_web/plugs/worker_healthcheck.ex

@@ -44,9 +44,8 @@ defmodule TransportWeb.Plugs.WorkerHealthcheck do
   end
 
   def app_started_recently? do
-    start_datetime = app_start_datetime()
     {delay, unit} = @app_start_waiting_delay
-    DateTime.before?(DateTime.utc_now(), DateTime.add(start_datetime, delay, unit))
+    DateTime.before?(DateTime.utc_now(), DateTime.add(app_start_datetime(), delay, unit))
   end
 
   def app_start_datetime do
@@ -56,9 +55,8 @@ defmodule TransportWeb.Plugs.WorkerHealthcheck do
   def app_start_datetime_cache_key_name, do: "#{__MODULE__}::app_start_datetime"
 
   def oban_attempted_jobs_recently? do
-    oban_last_attempt = oban_last_attempted_at()
     {delay, unit} = @oban_max_delay_since_last_attempt
-    DateTime.before?(oban_last_attempt, DateTime.add(oban_last_attempt, delay, unit))
+    DateTime.after?(oban_last_attempted_at(), DateTime.add(DateTime.utc_now(), -delay, unit))
   end
 
   def oban_last_attempted_at do

apps/transport/test/transport_web/plugs/worker_healthcheck_test.exs

@@ -0,0 +1,73 @@
+defmodule TransportWeb.Plugs.WorkerHealthcheckTest do
+  # async: false is required because we use real in-memory caching in these tests
+  use TransportWeb.ConnCase, async: false
+  alias TransportWeb.Plugs.WorkerHealthcheck
+
+  setup do
+    # Use a real in-memory cache for these tests to test the caching mecanism
+    old_value = Application.fetch_env!(:transport, :cache_impl)
+    Application.put_env(:transport, :cache_impl, Transport.Cache.Cachex)
+
+    on_exit(fn ->
+      Application.put_env(:transport, :cache_impl, old_value)
+      Cachex.reset(Transport.Cache.Cachex.cache_name())
+    end)
+
+    Ecto.Adapters.SQL.Sandbox.checkout(DB.Repo)
+  end
+
+  describe "healthy_state?" do
+    test "app was started recently, no Oban jobs" do
+      assert WorkerHealthcheck.app_started_recently?()
+      refute WorkerHealthcheck.oban_attempted_jobs_recently?()
+      assert WorkerHealthcheck.healthy_state?()
+    end
+
+    test "app was not started recently, Oban jobs have not been attempted recently" do
+      datetime = DateTime.add(DateTime.utc_now(), -30, :minute)
+      Cachex.put(Transport.Cache.Cachex.cache_name(), WorkerHealthcheck.app_start_datetime_cache_key_name(), datetime)
+
+      refute WorkerHealthcheck.app_started_recently?()
+      refute WorkerHealthcheck.oban_attempted_jobs_recently?()
+      refute WorkerHealthcheck.healthy_state?()
+    end
+
+    test "app was not started recently, Oban jobs have been attempted recently" do
+      datetime = DateTime.add(DateTime.utc_now(), -30, :minute)
+      Cachex.put(Transport.Cache.Cachex.cache_name(), WorkerHealthcheck.app_start_datetime_cache_key_name(), datetime)
+
+      # A completed job was attempted 55 minutes ago
+      Transport.Jobs.ResourceUnavailableJob.new(%{resource_id: 1})
+      |> Oban.insert!()
+      |> Ecto.Changeset.change(attempted_at: DateTime.add(DateTime.utc_now(), -55, :minute), state: "completed")
+      |> DB.Repo.update!()
+
+      refute WorkerHealthcheck.app_started_recently?()
+      assert WorkerHealthcheck.oban_attempted_jobs_recently?()
+      assert WorkerHealthcheck.healthy_state?()
+    end
+  end
+
+  describe "call" do
+    test "healthy system", %{conn: conn} do
+      assert WorkerHealthcheck.app_started_recently?()
+      refute WorkerHealthcheck.oban_attempted_jobs_recently?()
+      assert WorkerHealthcheck.healthy_state?()
+
+      assert conn |> WorkerHealthcheck.call(if: {__MODULE__, :plug_enabled?}) |> text_response(200)
+    end
+
+    test "unhealthy system", %{conn: conn} do
+      datetime = DateTime.add(DateTime.utc_now(), -30, :minute)
+      Cachex.put(Transport.Cache.Cachex.cache_name(), WorkerHealthcheck.app_start_datetime_cache_key_name(), datetime)
+
+      refute WorkerHealthcheck.app_started_recently?()
+      refute WorkerHealthcheck.oban_attempted_jobs_recently?()
+      refute WorkerHealthcheck.healthy_state?()
+
+      assert conn |> WorkerHealthcheck.call(if: {__MODULE__, :plug_enabled?}) |> text_response(503)
+    end
+  end
+
+  def plug_enabled?, do: true
+end