chore: display warning on deprecated <splash> tag usage (#1451)

* chore: display warning on deprecated <splash> tag usage
* test: create spy on warnForDeprecatedSplashScreen

lib/prepare.js

@@ -63,6 +63,7 @@ module.exports.prepare = function (cordovaProject, options) {
 
     // Update own www dir with project's www assets and plugins' assets and js-files
     return Promise.resolve(updateWww(cordovaProject, this.locations))
+        .then(() => warnForDeprecatedSplashScreen(cordovaProject))
         .then(() => updateProjectAccordingTo(self._config, self.locations))
         .then(function () {
             updateIcons(cordovaProject, path.relative(cordovaProject.root, self.locations.res));
@@ -353,6 +354,16 @@ function updateProjectStrings (platformConfig, locations) {
     events.emit('verbose', 'Wrote out android application name "' + name + '" to ' + locations.strings);
 }
 
+function warnForDeprecatedSplashScreen (cordovaProject) {
+    const hasOldSplashTags = (
+        cordovaProject.projectConfig.doc.findall('./platform[@name="android"]/splash') || []
+    ).length > 0;
+
+    if (hasOldSplashTags) {
+        events.emit('warn', 'The "<splash>" tags were detected and are no longer supported. Please migrate to the "preference" tag "AndroidWindowSplashScreenAnimatedIcon".');
+    }
+}
+
 /**
  * @param   {ConfigParser}  platformConfig  A project's configuration that will
  *   be used to update project