[Arr] increase code coverage

src/Psl/Arr/sort_with_keys_by.php

@@ -40,19 +40,21 @@ function sort_with_keys_by(iterable $iterable, callable $scalar_func, ?callable
             fn ($a, $b): int => $a[0] <=> $b[0];
     }
 
-    $result = Iter\map_with_key(
-        sort_with_keys(
-            Iter\map(
-                $iterable,
-                /**
-                 * @psalm-param  Tv $value
-                 *
-                 * @psalm-return array{0: Ts, 1: Tv}
-                 */
-                fn ($value) => [$scalar_func($value), $value],
-            ),
-            $tuple_comparator
+    $sorted = sort_with_keys(
+        Iter\map(
+            $iterable,
+            /**
+             * @psalm-param  Tv $value
+             *
+             * @psalm-return array{0: Ts, 1: Tv}
+             */
+            fn ($value) => [$scalar_func($value), $value],
         ),
+        $tuple_comparator
+    );
+
+    $result = Iter\map_with_key(
+        $sorted,
         /**
          * @psalm-param  Tk                     $k
          * @psalm-param  array{0: Ts, 1: Tv}    $v

tests/Psl/Arr/RandomTest.php

@@ -19,6 +19,14 @@ class RandomTest extends TestCase
         static::assertContains($value, $values);
     }
 
+    public function testRandomWithOneItem(): void
+    {
+        $values = ['a'];
+        $value = Arr\random($values);
+
+        static::assertSame('a', $value);
+    }
+
     public function testRandomThrowsWhenTheGivenArrayIsEmpty(): void
     {
         $this->expectException(Exception\InvariantViolationException::class);