feat(agent): add Diagnostics.Writer GenServer

agent/test/proxmox_agent/diagnostics/writer_test.exs

@@ -0,0 +1,83 @@
+defmodule ProxmoxAgent.Diagnostics.WriterTest do
+  use ExUnit.Case, async: false
+
+  alias ProxmoxAgent.Diagnostics.Writer
+
+  setup do
+    dir = Path.join(System.tmp_dir!(), "writer-#{System.unique_integer([:positive])}")
+    File.mkdir_p!(dir)
+    {:ok, pid} = Writer.start_link(dir: dir)
+
+    on_exit(fn ->
+      if Process.alive?(pid), do: GenServer.stop(pid)
+      File.rm_rf(dir)
+    end)
+
+    %{dir: dir, pid: pid}
+  end
+
+  test "handle_cast :command appends a formatted entry to commands.log", %{dir: dir, pid: pid} do
+    GenServer.cast(pid, {:command, "zpool", ["list", "-j"], {:ok, "hello body"}, 1_234})
+    :ok = GenServer.call(pid, :flush)
+
+    body = File.read!(Path.join(dir, "commands.log"))
+
+    assert body =~ "$ zpool list -j"
+    assert body =~ "exit=0"
+    assert body =~ "duration=1ms"
+    assert body =~ "size=10"
+    assert body =~ "hello body"
+    assert body =~ "=====\n"
+  end
+
+  test "handle_cast :command records errors in place of exit", %{dir: dir, pid: pid} do
+    GenServer.cast(pid, {:command, "zpool", ["list"], {:error, {:enoent, "zpool"}}, 300})
+    :ok = GenServer.call(pid, :flush)
+
+    body = File.read!(Path.join(dir, "commands.log"))
+    assert body =~ "error={:enoent, \"zpool\"}"
+    assert body =~ "duration=0ms"
+    refute body =~ "exit="
+  end
+
+  test "handle_cast :command formats non-zero exit results", %{dir: dir, pid: pid} do
+    GenServer.cast(pid, {:command, "/bin/sh", ["-c", "exit 7"], {:error, {:nonzero_exit, 7, "oops"}}, 500})
+    :ok = GenServer.call(pid, :flush)
+
+    body = File.read!(Path.join(dir, "commands.log"))
+    assert body =~ "exit=7"
+    assert body =~ "size=4"
+    assert body =~ "oops"
+  end
+
+  test "handle_cast :sample appends pretty-printed JSON to samples.log", %{dir: dir, pid: pid} do
+    GenServer.cast(pid, {:sample, "fast", %{"host" => %{"load1" => 0.1}}})
+    :ok = GenServer.call(pid, :flush)
+
+    body = File.read!(Path.join(dir, "samples.log"))
+    assert body =~ "kind=fast"
+    assert body =~ "\"host\""
+    assert body =~ "\"load1\""
+    assert body =~ "=====\n"
+  end
+
+  test "multiple casts serialize and do not interleave", %{dir: dir, pid: pid} do
+    for i <- 1..50 do
+      GenServer.cast(pid, {:command, "cmd#{i}", [], {:ok, "body#{i}"}, 1})
+    end
+
+    :ok = GenServer.call(pid, :flush)
+    body = File.read!(Path.join(dir, "commands.log"))
+
+    # Every body1..body50 must appear exactly once, in order.
+    for i <- 1..50 do
+      assert body =~ "body#{i}"
+    end
+  end
+
+  test "terminate closes handles cleanly", %{pid: pid} do
+    ref = Process.monitor(pid)
+    GenServer.stop(pid, :normal)
+    assert_receive {:DOWN, ^ref, :process, ^pid, :normal}, 1000
+  end
+end