feat: Added Set::union() method

src/JavaScript/Set.php

@@ -180,6 +180,19 @@ public function toArray(): array
         return $this->items;
     }
 
+    /**
+     * Merge the Set with the given Set.
+     * @link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set/union
+     *
+     * @param \Rudashi\JavaScript\Set<TValue> $other
+     *
+     * @return \Rudashi\JavaScript\Set<TValue>
+     */
+    public function union(Set $other): Set
+    {
+        return new Set([...$this->items, ...$other->items]);
+    }
+
     /**
      * Returns Set values as SetIterator.
      * @link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set/values

tests/Unit/SetTest.php

@@ -435,6 +435,35 @@
     });
 });
 
+describe('union', function () {
+    test('merge values', function () {
+        $odds = new Set([1, 3, 5, 7, 9]);
+        $squares = new Set([1, 4, 9]);
+
+        expect($odds->union($squares))
+            ->toBeInstanceOf(Set::class)
+            ->toMatchArray([1, 3, 5, 7, 9, 4]);
+    });
+
+    test('`a` plus `b`', function () {
+        $a = new Set([1, 2, 3, 4]);
+        $b = new Set([5, 4, 3, 2]);
+
+        expect($a->union($b))
+            ->toBeInstanceOf(Set::class)
+            ->toMatchArray([1, 2, 3, 4, 5]);
+    });
+
+    test('`b` plus `a`', function () {
+        $a = new Set([1, 2, 3, 4]);
+        $b = new Set([5, 4, 3, 2]);
+
+        expect($b->union($a))
+            ->toBeInstanceOf(Set::class)
+            ->toMatchArray([5, 4, 3, 2, 1]);
+    });
+});
+
 describe('values', function () {
     it('returns new SetIterator', function () {
         $set = new Set(['foo', 'bar']);