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Add TmpDir.await_cleanup/1 for reliable test synchronization #86

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Merged
ericmj merged 1 commit into from
Mar 29, 2026
Merged

Add TmpDir.await_cleanup/1 for reliable test synchronization #86

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27 changes: 25 additions & 2 deletions lib/hexdocs/tmp_dir.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,10 @@ defmodule Hexdocs.TmpDir do
dir
end

def await_cleanup(pid) do
GenServer.call(__MODULE__, {:await_cleanup, pid}, 5000)
end

defp track(path) do
pid = self()
:ets.insert(@table, {pid, path})
Expand All @@ -42,7 +46,7 @@ defmodule Hexdocs.TmpDir do
def init(_opts) do
Process.flag(:trap_exit, true)
:ets.new(@table, [:named_table, :duplicate_bag, :public])
{:ok, %{monitors: MapSet.new()}}
{:ok, %{monitors: MapSet.new(), waiters: %{}}}
end

@impl true
Expand All @@ -55,10 +59,29 @@ defmodule Hexdocs.TmpDir do
end
end

def handle_call({:await_cleanup, pid}, from, state) do
if pid in state.monitors do
waiters = Map.update(state.waiters, pid, [from], &[from | &1])
{:noreply, %{state | waiters: waiters}}
else
{:reply, :ok, state}
end
end

@impl true
def handle_info({:DOWN, _ref, :process, pid, _reason}, state) do
cleanup_pid(pid)
{:noreply, %{state | monitors: MapSet.delete(state.monitors, pid)}}

for from <- Map.get(state.waiters, pid, []) do
GenServer.reply(from, :ok)
end

{:noreply,
%{
state
| monitors: MapSet.delete(state.monitors, pid),
waiters: Map.delete(state.waiters, pid)
}}
end

@impl true
Expand Down
15 changes: 3 additions & 12 deletions test/hexdocs/tmp_dir_test.exs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,9 +22,8 @@ defmodule Hexdocs.TmpDirTest do
send(test_pid, {:paths, file, dir})
end)

ref = Process.monitor(task_pid)
assert_receive {:paths, file, dir}
wait_for_cleanup(task_pid, ref)
Hexdocs.TmpDir.await_cleanup(task_pid)

refute File.exists?(file)
refute File.exists?(dir)
Expand All @@ -42,9 +41,8 @@ defmodule Hexdocs.TmpDirTest do
raise "crash"
end)

ref = Process.monitor(task_pid)
assert_receive {:paths, file, dir}
wait_for_cleanup(task_pid, ref)
Hexdocs.TmpDir.await_cleanup(task_pid)

refute File.exists?(file)
refute File.exists?(dir)
Expand All @@ -65,9 +63,8 @@ defmodule Hexdocs.TmpDirTest do
send(test_pid, {:paths, paths})
end)

ref = Process.monitor(task_pid)
assert_receive {:paths, paths}
wait_for_cleanup(task_pid, ref)
Hexdocs.TmpDir.await_cleanup(task_pid)

for {file, dir} <- paths do
refute File.exists?(file)
Expand All @@ -82,10 +79,4 @@ defmodule Hexdocs.TmpDirTest do
assert File.exists?(file)
assert File.dir?(dir)
end

defp wait_for_cleanup(task_pid, ref) do
assert_receive {:DOWN, ^ref, :process, ^task_pid, _}, 5000
# Sync with the GenServer to ensure the :DOWN cleanup has been processed
:sys.get_state(Hexdocs.TmpDir)
end
end
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