feat(emulators): add emulators.launcher to override the emulator launch command

README.md

@@ -147,6 +147,8 @@ require("flutter-tools").setup {} -- use defaults
 - `FlutterDebug` - Force run current project in debug mode.
 - `FlutterDevices` - Brings up a list of connected devices to select from.
 - `FlutterEmulators` - Similar to devices but shows a list of emulators to choose from.
+  Set `emulators.launcher` to start the selected emulator with your own command instead of
+  `flutter emulator --launch`, see the [full configuration](#full-configuration).
 - `FlutterReload` - Reload the running project.
 - `FlutterRestart` - Restart the current project.
 - `FlutterQuit` - Ends a running session.
@@ -284,6 +286,16 @@ require("flutter-tools").setup {
   widget_preview = {
     web_server = true, -- open the widget previewer with vim.ui.open; false lets Flutter launch its own Chrome
   },
+  emulators = {
+    -- optional function to launch the emulator picked in `FlutterEmulators` with your own command,
+    -- e.g. the Android SDK `emulator` binary with extra flags; return nil to use `flutter emulator --launch`
+    -- launcher = function(emulator, paths)
+    --   if emulator.system ~= "android" then return nil end
+    --   local args = { "@" .. emulator.id, "-gpu", "host", "-accel", "on" }
+    --   if emulator.cold_boot then table.insert(args, "-no-snapshot-load") end
+    --   return { command = "emulator", args = args }
+    -- end,
+  },
   outline = {
     open_cmd = "30vnew", -- command to use to open the outline buffer
     auto_open = false -- if true this will open the outline automatically when it is first populated

lua/flutter-tools/config.lua

@@ -27,6 +27,13 @@ local utils = lazy.require("flutter-tools.utils") ---@module "flutter-tools.util
 ---@field flutter? table|string -- options applied to `flutter run` command
 ---@field dart? table|string -- options appliert to `dart run` command
 ---
+---@class flutter.EmulatorLaunchSpec
+---@field command string
+---@field args? string[]
+---
+---@class flutter.EmulatorsOpts
+---@field launcher? fun(emulator: Device, paths: flutter.Paths): flutter.EmulatorLaunchSpec?
+---
 ---@class flutter.Config
 ---@field flutter_path? string Path to the Flutter SDK
 ---@field flutter_lookup_cmd? string Command to find Flutter SDK
@@ -44,6 +51,7 @@ local utils = lazy.require("flutter-tools.utils") ---@module "flutter-tools.util
 ---@field dev_log? flutter.DevLogOpts
 ---@field dev_tools? {autostart: boolean, auto_open_browser: boolean}
 ---@field widget_preview? {web_server: boolean}
+---@field emulators? flutter.EmulatorsOpts
 ---@field analyzer_web_port? number
 
 local M = {}
@@ -152,6 +160,9 @@ local config = {
   widget_preview = {
     web_server = true,
   },
+  emulators = {
+    launcher = nil,
+  },
 }
 
 local deprecations = {

lua/flutter-tools/devices.lua

@@ -4,14 +4,12 @@ local ui = lazy.require("flutter-tools.ui") ---@module "flutter-tools.ui"
 local utils = lazy.require("flutter-tools.utils") ---@module "flutter-tools.utils"
 local commands = lazy.require("flutter-tools.commands") ---@module "flutter-tools.commands"
 local executable = lazy.require("flutter-tools.executable") ---@module "flutter-tools.executable"
+local config = lazy.require("flutter-tools.config") ---@module "flutter-tools.config"
 local fmt = string.format
 
 ---@alias Device {name: string, id: string, platform: string, system: string, type: integer, cold_boot: boolean}
 
-local M = {
-  ---@type Job
-  emulator_job = nil,
-}
+local M = {}
 
 local EMULATOR = 1
 local DEVICE = 2
@@ -180,19 +178,35 @@ end
 ---@param job Job
 local function handle_launch(job) ui.notify(utils.join(job:result())) end
 
-function M.close_emulator()
-  if M.emulator_job then M.emulator_job:shutdown() end
+---@param emulator Device
+---@param paths flutter.Paths
+---@return flutter.EmulatorLaunchSpec?
+local function custom_launch_spec(emulator, paths)
+  local launcher = config.emulators.launcher
+  if not launcher then return end
+  return launcher(emulator, paths)
 end
 
----@param emulator table
+---@param emulator Device
 function M.launch_emulator(emulator)
   if not emulator then return end
-  executable.flutter(function(cmd)
-    args = { "emulator", "--launch", emulator.id }
-    if emulator.cold_boot then table.insert(args, "--cold") end
-    M.emulator_job = Job:new({ command = cmd, args = args })
-    M.emulator_job:after_success(vim.schedule_wrap(handle_launch))
-    M.emulator_job:start()
+  executable.get(function(paths)
+    local spec = custom_launch_spec(emulator, paths)
+    local job
+    if spec then
+      job = Job:new({ command = spec.command, args = spec.args })
+      job:after_failure(
+        vim.schedule_wrap(
+          function(j) ui.notify(utils.join(j:stderr_result()), ui.ERROR, { timeout = 5000 }) end
+        )
+      )
+    else
+      local args = { "emulator", "--launch", emulator.id }
+      if emulator.cold_boot then table.insert(args, "--cold") end
+      job = Job:new({ command = paths.flutter_bin, args = args })
+      job:after_success(vim.schedule_wrap(handle_launch))
+    end
+    job:start()
   end)
 end
 

tests/devices_spec.lua

@@ -144,4 +144,84 @@ INFO    | Storing crashdata in: /tmp/android-ts/emu-crash-34.2.14.db, detection
       assert.is_nil(devices.resolve_default_device({ "not json" }))
     end)
   end)
+
+  describe("emulator launch - ", function()
+    local devices
+    local config
+    local jobs
+    local modules = {
+      "flutter-tools.devices",
+      "flutter-tools.config",
+      "flutter-tools.executable",
+      "plenary.job",
+    }
+    local paths = { flutter_bin = "/sdk/bin/flutter" }
+    local emulator = { id = "Pixel_8", name = "Pixel 8", system = "android", type = 1 }
+
+    before_each(function()
+      jobs = {}
+      for _, name in ipairs(modules) do
+        package.loaded[name] = nil
+      end
+      package.loaded["plenary.job"] = {
+        new = function(_, opts)
+          local job = { opts = opts, started = false }
+          function job:after_success() end
+          function job:after_failure() end
+          function job:start() self.started = true end
+          table.insert(jobs, job)
+          return job
+        end,
+      }
+      package.loaded["flutter-tools.executable"] = {
+        get = function(callback) callback(paths) end,
+      }
+      config = require("flutter-tools.config")
+      devices = require("flutter-tools.devices")
+    end)
+
+    after_each(function()
+      for _, name in ipairs(modules) do
+        package.loaded[name] = nil
+      end
+    end)
+
+    it("should launch through flutter by default", function()
+      devices.launch_emulator(vim.tbl_extend("force", emulator, { cold_boot = true }))
+
+      assert.equal(1, #jobs)
+      assert.equal("/sdk/bin/flutter", jobs[1].opts.command)
+      assert.same({ "emulator", "--launch", "Pixel_8", "--cold" }, jobs[1].opts.args)
+      assert.is_true(jobs[1].started)
+    end)
+
+    it("should use the command returned by a custom launcher", function()
+      local received
+      config.set({
+        emulators = {
+          launcher = function(e, p)
+            received = { emulator = e, paths = p }
+            return { command = "emulator", args = { "@" .. e.id, "-gpu", "host" } }
+          end,
+        },
+      })
+
+      devices.launch_emulator(emulator)
+
+      assert.equal(emulator, received.emulator)
+      assert.equal(paths, received.paths)
+      assert.equal("emulator", jobs[1].opts.command)
+      assert.same({ "@Pixel_8", "-gpu", "host" }, jobs[1].opts.args)
+      assert.is_true(jobs[1].started)
+    end)
+
+    it("should fall back to flutter when the launcher returns nil", function()
+      config.set({ emulators = { launcher = function() return nil end } })
+
+      devices.launch_emulator(emulator)
+
+      assert.equal("/sdk/bin/flutter", jobs[1].opts.command)
+      assert.same({ "emulator", "--launch", "Pixel_8" }, jobs[1].opts.args)
+    end)
+  end)
 end)