[FEATURE] clean build folder: Allows developers to clean build folder before start building a project

Author: mauriciolauffer

lib/builder/builder.js

@@ -1,3 +1,5 @@
+const {promisify} = require("util");
+const rimraf = promisify(require("rimraf"));
 const log = require("@ui5/logger").getGroupLogger("builder:builder");
 const resourceFactory = require("@ui5/fs").resourceFactory;
 const MemAdapter = require("@ui5/fs").adapters.Memory;
@@ -203,6 +205,7 @@ module.exports = {
 	 * @param {Object} parameters Parameters
 	 * @param {Object} parameters.tree Dependency tree
 	 * @param {string} parameters.destPath Target path
+	 * @param {boolean} [parameters.cleanDest=false] Decides whether project should clean the target path before build
 	 * @param {boolean} [parameters.buildDependencies=false] Decides whether project dependencies are built as well
 	 * @param {boolean} [parameters.dev=false] Decides whether a development build should be activated (skips non-essential and time-intensive tasks)
 	 * @param {boolean} [parameters.selfContained=false] Flag to activate self contained build
@@ -213,7 +216,7 @@ module.exports = {
 	 * @returns {Promise} Promise resolving to <code>undefined</code> once build has finished
 	 */
 	async build({
-		tree, destPath,
+		tree, destPath, cleanDest = false,
 		buildDependencies = false, dev = false, selfContained = false, jsdoc = false,
 		includedTasks = [], excludedTasks = [], devExcludeProject = []
 	}) {
@@ -342,6 +345,9 @@ module.exports = {
 		}
 
 		try {
+			if (cleanDest) {
+				await rimraf(destPath);
+			}
 			await buildProject(tree);
 			log.info(`Build succeeded in ${getElapsedTime(startTime)}`);
 		} catch (err) {

test/lib/builder/builder.js

@@ -129,6 +129,34 @@ test("Build application.a [dev mode]", (t) => {
 	});
 });
 
+test("Build application.a and clean target path [dev mode]", (t) => {
+	const destPath = "./test/tmp/build/application.a/dest-clean";
+	const destPathRubbishSubFolder = destPath + "/rubbish-should-be-deleted";
+	const expectedPath = path.join("test", "expected", "build", "application.a", "dest-dev");
+
+	return builder.build({
+		tree: applicationATree,
+		destPath: destPathRubbishSubFolder,
+		dev: true
+	}).then(() => {
+		return builder.build({
+			tree: applicationATree,
+			destPath,
+			cleanDest: true,
+			dev: true
+		});
+	}).then(() => {
+		return findFiles(expectedPath);
+	}).then((expectedFiles) => {
+		// Check for all directories and files
+		assert.directoryDeepEqual(destPath, expectedPath);
+		// Check for all file contents
+		return checkFileContentsIgnoreLineFeeds(expectedFiles, expectedPath, destPath);
+	}).then(() => {
+		t.pass();
+	});
+});
+
 test("Build application.g", (t) => {
 	const destPath = "./test/tmp/build/application.g/dest";
 	const expectedPath = path.join("test", "expected", "build", "application.g", "dest");