langium: extended Multimap constructor to accept an Iterable of initial data. (#2020)

added corresponding tests

Author: sailingKieler

packages/langium/src/utils/collections.ts

@@ -15,8 +15,8 @@ export class MultiMap<K, V> {
     private map = new Map<K, V[]>();
 
     constructor()
-    constructor(elements: Array<[K, V]>)
-    constructor(elements?: Array<[K, V]>) {
+    constructor(elements: Iterable<[K, V]>)
+    constructor(elements?: Iterable<[K, V]>) {
         if (elements) {
             for (const [key, value] of elements) {
                 this.add(key, value);

packages/langium/test/utils/collections.test.ts

@@ -5,10 +5,22 @@
  ******************************************************************************/
 
 import { describe, expect, test } from 'vitest';
-import { MultiMap } from 'langium';
+import { MultiMap, stream } from 'langium';
 
 describe('MultiMap', () => {
 
+    test('constructor with array', () => {
+        const multimap = new MultiMap<string, string>([['a', 'foo'], ['a', 'bar'], ['b', 'baz']]);
+        expect(multimap.size).toBe(3);
+        expect(multimap.keys().toArray().length).toBe(2);
+    });
+
+    test('constructor with iterable', () => {
+        const multimap = new MultiMap<string, string>(stream([['a', 'foo'], ['a', 'bar'], ['b', 'baz']]));
+        expect(multimap.size).toBe(3);
+        expect(multimap.keys().toArray().length).toBe(2);
+    });
+
     test('addAll when empty', () => {
         const multimap = new MultiMap<string, string>();
         multimap.addAll('a', ['foo', 'bar', 'baz']);