Application tests

Renderer-independent tests prove Elixir application behavior without compiling or loading GPUI. They are the default for state transitions, callbacks, validation, snapshots, topology, event policy, and supervised integration.

Use asynchronous ExUnit where the application under test permits it:

defmodule MyApp.FocusTimerTest do
  use GPUI.Test, async: true

  test "starts and receives OTP ticks" do
    runtime = start_runtime!(GettingStarted.FocusTimer.App, args: %{seconds: 2})

    click(runtime, "start")
    send_view(runtime, :tick)

    assert %{remaining: 1, status: :running} = assigns(runtime)
  end
end

start_runtime!/2 starts a supervised GPUI.Runtime backed by GPUI.Test.Display. Events pass through the same runtime polling and session dispatch boundaries used by a real display.

Render and query views

Render a view directly when runtime behavior is not needed:

tree = render(MyApp.ProfileView, name: "Ada", editing: false)
assert %GPUI.Element{type: :ui_input} = find!(tree, id: "name")
assert [_button] = all(tree, type: :ui_button)

Runtime helpers expose snapshots, selected windows, assigns, and rendered trees:

snapshot = snapshot(runtime)
window = window_snapshot(snapshot, "Settings")
assigns = assigns(runtime)
tree = tree(runtime)

render/2 returns the original %GPUI.Element{} tree, while tree/2 returns the snapshot-encoded map sent across display boundaries. find/2, find!/2, and all/2 intentionally query either representation; pattern matches should use the corresponding struct or map shape.

Dispatch semantic events

Use the helper matching the component contract:

click(runtime, "save")
command(runtime, "reload_repository")
change(runtime, "name_changed", "Ada")
submit(runtime, "save", "Ada")
select(runtime, "language_changed", "elixir")
search(runtime, "framework_searched", "live")
change(runtime, "notifications_changed", true)
change(runtime, "details_changed", ["account"])
change(runtime, "volume_changed", 75.0)
release(runtime, "volume_released", 75.0)
change(runtime, "dialog_open_changed", true)
file_select(runtime, "source_selected", "fixture.png", encoded_png)
file_cancel(runtime, "source_selected")
range(runtime, "records_range", 1_000, 1_048)

All helpers return the resulting snapshot. dispatch/2 remains available for a custom explicit typed event:

dispatch(runtime, %{
  type: :select,
  window_id: 1,
  event: "file_menu_selected",
  value: "new"
})

Every routed event requires a positive window_id, a non-empty event name, and the value shape required by its type; a missing type never defaults to :click. Convenience helpers construct those fields for tests.

send_view/3 delivers an OTP message through GPUI.Runtime.send_view/3, making background-process behavior deterministic without running timers in a test.

What this layer proves

Application tests should own:

• mount/1, handle_event/3, handle_info/2, and window callback behavior;
• controlled assigns and authoritative rerenders;
• schema, template, and payload validation;
• snapshot topology and dynamic windows;
• source-backed range and selection policy;
• remote protocol, reconnection, and synchronization policy;
• text-buffer transactions that do not require a mounted native surface.

They do not prove where GPUI laid out an element, whether native focus moved, whether a key reached a component, or whether the operating system completed a clipboard or IME operation. Use Deterministic native tests or Desktop E2E and visual evidence for those facts.

Repository test layout

The repository separates tests by purpose:

• test/gpui/ contains focused units, deterministic view-state tests, schema/template tests, and deterministic native interaction tests;
• test/integration/gpui/examples/ contains example source processes, Logger/ETS/filesystem work, cancellation, and other cross-process flows;
• test/integration/ contains remaining runtime, transport, and remote flows;
• apps/gpui_native/test/e2e/ contains real native-window tests;
• test/support/ contains reusable displays and native drivers.

Run focused renderer-independent layers with:

mix test test/gpui test/gpui_test.exs
mix test test/integration

Tests under test/gpui/test/native/ are selected by the dedicated native-test Mix target and are not part of the ordinary renderer-independent command.