#2: Add support for multiple elements to be added at once

src/AdvancedSet.ts

@@ -14,8 +14,8 @@ export default class AdvancedSet<T> {
     return this._set.has(val);
   }
 
-  public add(val: T): AdvancedSet<T> {
-    this._set.add(val);
+  public add(...vals: T[]): AdvancedSet<T> {
+    for (const val of vals) this._set.add(val);
     return this;
   }
 
@@ -120,6 +120,6 @@ export default class AdvancedSet<T> {
     return this.intersection(setB).isEmpty();
   }
 
-  // partialSubset, isProperSubsetOf, isProperSupersetOf, multi set intersection,
+  // isProperSubsetOf, isProperSupersetOf, multi set intersection,
   // power sets, subset by function
 }

src/__tests__/Add.test.ts

@@ -0,0 +1,21 @@
+import AdvancedSet from '../AdvancedSet';
+
+test('Add nothing to empty set should be empty set', () => {
+  expect(new AdvancedSet().add().toArray()).toMatchObject([]);
+});
+
+test('Empty set adding a value should be a set with just that value', () => {
+  expect(new AdvancedSet().add(1).toArray()).toMatchObject([1]);
+});
+
+test('Non emtpy set adding a value should be the set with the new value', () => {
+  expect(new AdvancedSet(2, 3).add(1).toArray().sort()).toMatchObject([1, 2, 3].sort());
+});
+
+test('Non empty set adding nothing should be just that set', () => {
+  expect(new AdvancedSet(4, 5).add().toArray().sort()).toMatchObject([4, 5].sort());
+});
+
+test('Advanced sets should allow for multiple items to be added at the same time', () => {
+  expect(new AdvancedSet(2, 3, 5).add(1, 4).toArray().sort()).toMatchObject([1, 2, 3, 4, 5].sort());
+});