fix(helpers): prevent uniqueArray from hanging (#2239)

Author: matthewmayer

src/modules/helpers/index.ts

@@ -649,6 +649,11 @@ export class HelpersModule {
    * and outputs a unique array of strings based on that source.
    * This method does not store the unique state between invocations.
    *
+   * If there are not enough unique values to satisfy the length, if
+   * the source is an array, it will only return as many items as are
+   * in the array. If the source is a function, it will return after
+   * a maximum number of attempts has been reached.
+   *
    * @template T The type of the elements.
    *
    * @param source The strings to choose from or a function that generates a string.
@@ -671,8 +676,11 @@ export class HelpersModule {
     const set = new Set<T>();
     try {
       if (typeof source === 'function') {
-        while (set.size < length) {
+        const maxAttempts = 1000 * length;
+        let attempts = 0;
+        while (set.size < length && attempts < maxAttempts) {
           set.add(source());
+          attempts++;
         }
       }
     } catch {

test/helpers.spec.ts

@@ -806,6 +806,14 @@ describe('helpers', () => {
           expect(unique).toHaveLength(input.length);
         });
 
+        it('function with length longer than possible values returns', () => {
+          const fn = () => faker.helpers.arrayElement(['a', 'b']);
+          const length = 3;
+          const unique = faker.helpers.uniqueArray(fn, length);
+          expect(unique).not.toContainDuplicates();
+          expect(unique).toHaveLength(2);
+        });
+
         it('works as expected when seeded', () => {
           const input = ['a', 'a', 'a', 'a', 'a', 'f', 'g', 'h', 'i', 'j'];
           const length = 5;