Add browser_launch_opts config option

lib/phoenix_test/playwright/config.ex

@@ -12,6 +12,14 @@ browser_opts = [
     type: {:in, browsers},
     type_doc: "`#{Enum.map_join(browsers, " | ", &":#{&1}")}`"
   ],
+  browser_launch_opts: [
+    default: [],
+    type: :keyword_list,
+    doc: """
+    Additional arguments passed to Playwright [browserType.launch](https://playwright.dev/docs/api/class-browsertype#browser-type-launch).
+    E.g. `[args: ["--use-fake-ui-for-media-stream", "--use-fake-device-for-media-stream"]]`.
+    """
+  ],
   browser_launch_timeout: [
     default: to_timeout(second: 4),
     type: :non_neg_integer
@@ -60,6 +68,7 @@ schema_opts = [
     """
   ],
   browser: browser_opts[:browser],
+  browser_launch_opts: browser_opts[:browser_launch_opts],
   browser_context_opts: [
     default: [],
     type: {:or, [:map, :keyword_list]},
@@ -172,9 +181,9 @@ schema_opts = [
 
 schema = NimbleOptions.new!(schema_opts)
 
-setup_all_keys = ~w(browser_pool browser browser_launch_timeout executable_path headless slow_mo)a
+setup_all_keys = ~w(browser_pool browser browser_launch_opts browser_launch_timeout executable_path headless slow_mo)a
 setup_keys = ~w(accept_dialogs ecto_sandbox_stop_owner_delay screenshot trace browser_context_opts browser_page_opts)a
-merge_global_into_browser_pool_keys = ~w(browser browser_launch_timeout headless slow_mo)a
+merge_global_into_browser_pool_keys = ~w(browser browser_launch_opts browser_launch_timeout headless slow_mo)a
 
 defmodule PhoenixTest.Playwright.Config do
   @moduledoc """

lib/phoenix_test/playwright/internal/browser.ex

@@ -7,7 +7,9 @@ defmodule PhoenixTest.Playwright.Browser do
   def launch_browser!(config) do
     {launch_timeout, opts} = Keyword.pop!(config, :browser_launch_timeout)
     {browser, opts} = Keyword.pop!(opts, :browser)
+    {launch_opts, opts} = Keyword.pop!(opts, :browser_launch_opts)
     opts = opts |> Keyword.put(:timeout, launch_timeout) |> Keyword.delete(:browser_pool)
+    opts = Keyword.merge(opts, launch_opts)
 
     case PlaywrightEx.launch_browser(browser, opts) do
       {:ok, browser} ->

test/phoenix_test/playwright/browser_launch_opts_test.exs

@@ -0,0 +1,58 @@
+defmodule PhoenixTest.Playwright.BrowserLaunchOptsTest do
+  @moduledoc """
+  Tests that browser_launch_opts are passed through to Playwright.
+
+  These tests verify that browser launch flags actually affect browser behavior
+  by testing getUserMedia with and without fake media device flags.
+  """
+
+  use PhoenixTest.Playwright.Case,
+    async: true,
+    browser_pool: false,
+    browser_launch_opts: [
+      args: [
+        "--use-fake-ui-for-media-stream",
+        "--use-fake-device-for-media-stream"
+      ]
+    ]
+
+  test "getUserMedia succeeds with fake media device flags", %{conn: conn} do
+    conn
+    |> visit("/pw/live")
+    |> assert_has("h1")
+    |> evaluate(
+      """
+      navigator.mediaDevices.getUserMedia({ audio: true })
+        .then(() => "success")
+        .catch(e => "error: " + e.name)
+      """,
+      &assert(&1 == "success")
+    )
+  end
+end
+
+defmodule PhoenixTest.Playwright.BrowserLaunchOptsWithoutFlagsTest do
+  @moduledoc """
+  Tests that getUserMedia fails WITHOUT the fake media device flags.
+  This proves the flags in BrowserLaunchOptsTest actually have an effect.
+  """
+
+  use PhoenixTest.Playwright.Case,
+    async: true,
+    browser_pool: false
+
+  test "getUserMedia fails without fake media device flags", %{conn: conn} do
+    conn
+    |> visit("/pw/live")
+    |> assert_has("h1")
+    |> evaluate(
+      """
+      navigator.mediaDevices.getUserMedia({ audio: true })
+        .then(() => "success")
+        .catch(e => "error: " + e.name)
+      """,
+      # Without fake device flags, getUserMedia should fail in headless mode
+      &assert(&1 =~ "error:")
+    )
+  end
+end