feat: disable pasteboard sync in launching time to improve the perfor…

…mance (#262)

* feat: improve launching simulator performance with disabling pasteboard sync

* make disablePasteboardAutomaticSync configuable

* fix review

* tweak docstring

* allow to set pasteboardAutomaticSync as on, off or system

* tweak warning message

lib/simulator-xcode-6.js

@@ -424,22 +424,32 @@ class SimulatorXcode6 extends EventEmitter {
     return indicator;
   }
 
+
   /**
-   * Start the Simulator UI client with the given arguments
-   *
-   * @param {object} opts - One or more of available Simulator UI client options:
-   *   - {string} scaleFactor: can be one of ['1.0', '0.75', '0.5', '0.33', '0.25'].
-   *   Defines the window scale value for the UI client window for the current Simulator.
+   * @typedef {Object} SimulatorOptions
+   * @property {?string} scaleFactor [null] - Defines the window scale value for the UI client window for the current Simulator.
    *   Equals to null by default, which keeps the current scale unchanged.
-   *   - {boolean} connectHardwareKeyboard: whether to connect the hardware keyboard to the
-   *   Simulator UI client. Equals to false by default.
-   *   - {number} startupTimeout: number of milliseconds to wait until Simulator booting
+   *   It should be one of ['1.0', '0.75', '0.5', '0.33', '0.25'].
+   * @property {boolean} connectHardwareKeyboard [false] - Whether to connect the hardware keyboard to the
+   *   Simulator UI client. Defaults to false.
+   * @property {string} pasteboardAutomaticSync ['off'] - Whether to disable pasteboard sync with the
+   *   Simulator UI client or respect the system wide preference. 'on', 'off', or 'system' is available.
+   *   The sync increases launching simulator process time, but it allows system to sync pasteboard
+   *   with simulators. Follows system-wide preference if the value is 'system'.
+   *   Defaults to 'off'.
+   * @property {number} startupTimeout [60000] - Number of milliseconds to wait until Simulator booting
    *   process is completed. The default timeout will be used if not set explicitly.
    */
+
+  /**
+   * Start the Simulator UI client with the given arguments
+   * @param {SimulatorOptions} opts - Simulator launching options
+   */
   async startUIClient (opts = {}) {
     opts = Object.assign({
       scaleFactor: null,
       connectHardwareKeyboard: false,
+      pasteboardAutomaticSync: 'off',
       startupTimeout: this.startupTimeout,
     }, opts);
 
@@ -457,6 +467,23 @@ class SimulatorXcode6 extends EventEmitter {
       args.push('-ConnectHardwareKeyboard', opts.connectHardwareKeyboard ? '1' : '0');
     }
 
+    switch (_.lowerCase(opts.pasteboardAutomaticSync)) {
+      case 'on':
+        args.push('-PasteboardAutomaticSync', '1');
+        break;
+      case 'off':
+        // Improve launching simulator performance
+        // https://github.com/WebKit/webkit/blob/master/Tools/Scripts/webkitpy/xcode/simulated_device.py#L413
+        args.push('-PasteboardAutomaticSync', '0');
+        break;
+      case 'system':
+        // Do not add -PasteboardAutomaticSync
+        break;
+      default:
+        log.warn(`['on', 'off' or 'system'] are available as the pasteboard automatic sync option. Defaulting to 'off'.`);
+        args.push('-PasteboardAutomaticSync', '0');
+    }
+
     log.info(`Starting Simulator UI with command: open ${args.join(' ')}`);
     try {
       await exec('open', args, {timeout: opts.startupTimeout});