Add benchmarks

benchmark.js

@@ -0,0 +1,68 @@
+'use strict';
+const path = require('path');
+const Benchmark = require('benchmark');
+const makeDir = require('make-dir');
+const tempy = require('tempy');
+const del = require('.');
+
+const suite = new Benchmark.Suite('concurrency');
+
+const tempDir = tempy.directory();
+
+const fixtures = Array.from({length: 2000}, (x, index) => {
+	return path.resolve(tempDir, (index + 1).toString());
+});
+
+function createFixtures() {
+	for (const fixture of fixtures) {
+		makeDir.sync(path.resolve(tempDir, fixture));
+	}
+}
+
+const concurrencies = [1, 3, 5, 10, 15, 20, 50, 100, 200, 300, 400, 500, 1000, Infinity];
+
+for (const concurrency of concurrencies) {
+	const name = `concurrency: ${concurrency.toString()}`;
+
+	suite.add({
+		name,
+		defer: true,
+		setup() {}, // This line breaks async await
+		async fn(deferred) {
+			// Can't use setup because it isn't called after every defer
+			// https://github.com/bestiejs/benchmark.js/issues/136
+			createFixtures();
+
+			const removedFiles = await del(['**/*'], {
+				cwd: tempDir,
+				concurrency
+			});
+
+			if (removedFiles.length !== fixtures.length) {
+				const error = new Error(
+					`"${name}": files removed: ${removedFiles.length}, expected: ${fixtures.length}`,
+				);
+
+				console.error(error);
+
+				del.sync(tempDir, {cwd: tempDir, force: true});
+
+				// eslint-disable-next-line unicorn/no-process-exit
+				process.exit(1);
+			}
+
+			deferred.resolve();
+		}
+	});
+}
+
+suite
+	.on('cycle', event => {
+		console.log(String(event.target));
+	})
+	.on('complete', function () {
+		console.log(`Fastest is ${this.filter('fastest').map('name')}`);
+
+		del.sync(tempDir, {cwd: tempDir, force: true});
+	})
+	.run({async: true});

package.json

@@ -13,7 +13,8 @@
 		"node": ">=8"
 	},
 	"scripts": {
-		"test": "xo && ava && tsd"
+		"test": "xo && ava && tsd",
+		"bench": "node benchmark.js"
 	},
 	"files": [
 		"index.js",
@@ -53,6 +54,7 @@
 	},
 	"devDependencies": {
 		"ava": "^2.3.0",
+		"benchmark": "^2.1.4",
 		"make-dir": "^3.0.0",
 		"tempy": "^0.3.0",
 		"tsd": "^0.7.3",