fix: Properly pass this context to getScreenSize helper (#189)

lib/commands/general.js

@@ -1,11 +1,21 @@
 import _ from 'lodash';
 import { util } from 'appium/support';
 
-async function getScreenSize (log) {
+/**
+ * @typedef {Object} Size
+ * @property {number} width
+ * @property {number} height
+ */
+
+/**
+ * @this {import('../driver').WindowsDriver}
+ * @returns {Promise<Size>}
+ */
+async function getScreenSize () {
   const dimensions = await this.execPowerShell({
     command: 'Add-Type -AssemblyName System.Windows.Forms;[System.Windows.Forms.Screen]::PrimaryScreen.Bounds.Size',
   });
-  log.debug(`Screen size information retrieved: ${dimensions}`);
+  this.log.debug(`Screen size information retrieved: ${dimensions}`);
   const match = /^\s*(True|False)\s+(\d+)\s+(\d+)/m.exec(dimensions);
   if (!match) {
     throw new Error('Cannot retrieve the screen size. Check the server log for more details');
@@ -20,6 +30,9 @@ const commands = {};
 
 // The next two commands are required
 // for proper `-image` locator functionality
+/**
+ * @returns {Promise<Size>}
+ */
 commands.getWindowSize = async function getWindowSize () {
   const size = await this.winAppDriver.sendCommand('/window/size', 'GET');
   if (_.isPlainObject(size)) {
@@ -28,7 +41,7 @@ commands.getWindowSize = async function getWindowSize () {
   // workaround for https://github.com/microsoft/WinAppDriver/issues/1104
   this.log.info('Cannot retrieve window size from WinAppDriver');
   this.log.info('Falling back to Windows Forms to calculate dimensions');
-  return await getScreenSize(this.log);
+  return await getScreenSize.bind(this)();
 };
 
 // a workaround for https://github.com/appium/appium/issues/15923