Add makeRange() helper method

index.d.ts

@@ -10,9 +10,21 @@ export interface Options {
 	readonly host?: string;
 }
 
-/**
- * Get an available TCP port number.
- *
- * @returns Port number.
- */
-export default function getPort(options?: Options): Promise<number>;
+declare const getPort: {
+  /**
+   * Get an available TCP port number.
+   *
+   * @returns Port number.
+   */
+  (options?: Options): Promise<number>;
+
+  /**
+   * Make a range of ports [from,to).
+   * @param from - First port of range(inclusive)
+   * @param to - Last port of range(exclusive)
+   * @returns Array with ports in range.
+   */
+  makeRange(from: number, to: number): number[];
+}
+
+export default getPort;

index.js

@@ -32,4 +32,21 @@ module.exports = options => options ?
 	getPort(options).catch(() => getPort(Object.assign(options, {port: 0}))) :
 	getPort({port: 0});
 
+module.exports.makeRange = (from, to) => {
+	if (!Number.isInteger(from) || !Number.isInteger(to) || from <= 1024 || to <= 1024 || from > 65535 || to > 65535) {
+		throw new TypeError('`from` and `to` port numbers must be integers in range (1023,65535]');
+	}
+
+	if (from > to) {
+		throw new Error('`from` port must be less than or equal to `to` port');
+	}
+
+	const ports = [];
+	for (let port = from; port < to; port++) {
+		ports.push(port);
+	}
+
+	return ports;
+};
+
 module.exports.default = module.exports;

index.test-d.ts

@@ -5,3 +5,5 @@ expectType<number>(await getPort());
 expectType<number>(await getPort({port: 3000}));
 expectType<number>(await getPort({port: [3000, 3001, 3002]}));
 expectType<number>(await getPort({host: 'https://localhost'}));
+
+expectType<number[]>(await getPort.makeRange(1025, 1026));

test.js

@@ -93,3 +93,13 @@ test('all preferred ports in array are unavailable', async t => {
 	t.not(port, desiredPorts[0]);
 	t.not(port, desiredPorts[1]);
 });
+
+test('makeRange', t => {
+	t.throws(() => getPort.makeRange(0, 0));
+	t.throws(() => getPort.makeRange(1024, 1024));
+	t.throws(() => getPort.makeRange(65536, 65536));
+	t.throws(() => getPort.makeRange(1026, 1025));
+
+	t.deepEqual(getPort.makeRange(1025, 1026), [1025]);
+	t.deepEqual(getPort.makeRange(1025, 1028), [1025, 1026, 1027]);
+});