Update randomElements to return random number of elements when no count is provided (#658)

Author: calebdw

src/Faker/Provider/Base.php

@@ -179,8 +179,10 @@ public static function randomAscii()
     /**
      * Returns randomly ordered subsequence of $count elements from a provided array
      *
+     * @todo update default $count to `null` (BC) for next major version
+     *
      * @param array|class-string|\Traversable $array           Array to take elements from. Defaults to a-c
-     * @param int                             $count           Number of elements to take.
+     * @param int|null                        $count           Number of elements to take. If `null` then returns random number of elements
      * @param bool                            $allowDuplicates Allow elements to be picked several times. Defaults to false
      *
      * @throws \InvalidArgumentException
@@ -211,14 +213,18 @@ public static function randomElements($array = ['a', 'b', 'c'], $count = 1, $all
 
         $numberOfElements = count($elements);
 
-        if (!$allowDuplicates && $numberOfElements < $count) {
+        if (!$allowDuplicates && null !== $count && $numberOfElements < $count) {
             throw new \LengthException(sprintf(
                 'Cannot get %d elements, only %d in array',
                 $count,
                 $numberOfElements,
             ));
         }
 
+        if (null === $count) {
+            $count = mt_rand(1, $numberOfElements);
+        }
+
         $randomElements = [];
 
         $keys = array_keys($elements);

test/Faker/Provider/BaseTest.php

@@ -580,6 +580,11 @@ public function testRandomElementsWorksWithoutArgument(): void
         self::assertCount(1, BaseProvider::randomElements(), 'Should work without any input');
     }
 
+    public function testRandomElementsReturnsRandomCountWhenNull(): void
+    {
+        self::assertCount(2, BaseProvider::randomElements(['foo', 'bar', 'baz'], null), 'Should return random count when null');
+    }
+
     public function testRandomElementsWorksWithEmptyArray(): void
     {
         $randomElements = BaseProvider::randomElements([], 0);