aprs.me/test/aprsme/telemetry/database_metrics_test.exs

115 lines
4 KiB
Elixir

defmodule Aprsme.Telemetry.DatabaseMetricsTest do
# Uses DataCase for a sandbox DB checkout — some metrics run live queries
# against pg_stat_* views. async: false because we mutate :aprsme :env
# in one test.
use Aprsme.DataCase, async: false
alias Aprsme.Telemetry.DatabaseMetrics
defp attach_collector(event, tag \\ to_string(System.unique_integer([:positive]))) do
test_pid = self()
handler_id = "test-#{tag}-#{Enum.join(event, ",")}"
:telemetry.attach(
handler_id,
event,
fn ^event, measurements, metadata, _ ->
send(test_pid, {:telemetry, event, measurements, metadata})
end,
nil
)
on_exit(fn -> :telemetry.detach(handler_id) end)
handler_id
end
describe "collect_postgres_metrics/0 in :test env" do
test "is a no-op returning :ok" do
original = Application.get_env(:aprsme, :env)
Application.put_env(:aprsme, :env, :test)
try do
assert DatabaseMetrics.collect_postgres_metrics() == :ok
after
Application.put_env(:aprsme, :env, original)
end
end
end
describe "collect_db_pool_metrics/0" do
test "emits [:aprsme, :repo, :pool] telemetry with pool_size from config" do
attach_collector([:aprsme, :repo, :pool])
DatabaseMetrics.collect_db_pool_metrics()
assert_receive {:telemetry, [:aprsme, :repo, :pool], measurements, _}, 1_000
assert Map.has_key?(measurements, :size)
assert Map.has_key?(measurements, :idle)
assert Map.has_key?(measurements, :busy)
assert Map.has_key?(measurements, :available)
assert Map.has_key?(measurements, :queue_length)
assert Map.has_key?(measurements, :total)
end
end
describe "collect_pgbouncer_metrics/0" do
test "is a no-op returning :ok" do
assert DatabaseMetrics.collect_pgbouncer_metrics() == :ok
end
end
describe "collect_db_pool_metrics/0 when Repo is not running" do
test "emits unavailable metrics when no Repo is registered" do
# Stop the Repo for this test — we need to restart it afterward to avoid
# breaking downstream tests.
repo_pid = Process.whereis(Aprsme.Repo)
if repo_pid do
# Temporarily unregister without stopping to avoid disrupting other tests.
:erlang.unregister(Aprsme.Repo)
on_exit(fn ->
if !Process.whereis(Aprsme.Repo) do
true = Process.register(repo_pid, Aprsme.Repo)
end
end)
end
attach_collector([:aprsme, :repo, :pool])
DatabaseMetrics.collect_db_pool_metrics()
assert_receive {:telemetry, [:aprsme, :repo, :pool], measurements, _}, 1_000
# The "unavailable" helper reports mostly zeros.
assert measurements.size == Application.get_env(:aprsme, Aprsme.Repo)[:pool_size] || 10
assert measurements.idle == 0
assert measurements.busy == 0
end
end
describe "collect_postgres_metrics/0 outside :test env" do
test "emits database, connections, packets_table and query_stats telemetry events" do
original = Application.get_env(:aprsme, :env)
Application.put_env(:aprsme, :env, :prod)
# Attach collectors for every event emitted by the helpers.
attach_collector([:aprsme, :postgres, :database])
attach_collector([:aprsme, :postgres, :connections])
attach_collector([:aprsme, :postgres, :packets_table])
# Query stats requires pg_stat_statements which may not be loaded —
# don't assert on that one, just call the function.
try do
DatabaseMetrics.collect_postgres_metrics()
after
Application.put_env(:aprsme, :env, original)
end
assert_receive {:telemetry, [:aprsme, :postgres, :database], %{size_bytes: size}, _}, 2_000
assert is_number(size) and size > 0
assert_receive {:telemetry, [:aprsme, :postgres, :connections], conn_metrics, _}, 2_000
assert Map.has_key?(conn_metrics, :total)
assert Map.has_key?(conn_metrics, :active)
assert Map.has_key?(conn_metrics, :idle)
end
end
end