From 9a3182fe25affaccfa809ffdaa7f833f6241f67e Mon Sep 17 00:00:00 2001
From: Alexey Kopytko <alexey@kopytko.com>
Date: Sat, 15 Apr 2023 13:37:46 +0900
Subject: [PATCH] Discard the state in reservoir() for invalid arguments

Fixes #120
---
 src/Standard.php        |  3 +++
 tests/ReservoirTest.php | 10 ++++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/Standard.php b/src/Standard.php
index 8e1486a..7f9b800 100644
--- a/src/Standard.php
+++ b/src/Standard.php
@@ -778,6 +778,9 @@ public function reservoir(int $size, ?callable $weightFunc = null): array
         }
 
         if ($size <= 0) {
+            // Discard the state to emulate full consumption
+            $this->pipeline = null;
+
             return [];
         }
 
diff --git a/tests/ReservoirTest.php b/tests/ReservoirTest.php
index 64e2abb..1eef213 100644
--- a/tests/ReservoirTest.php
+++ b/tests/ReservoirTest.php
@@ -158,9 +158,15 @@ public static function provideWeightedInputs(): iterable
      */
     public function testWeightedSampleFromGenerator(array $input, int $size, callable $weightFn, array $expected): void
     {
-        $this->assertSame($expected, map(static function () use ($input) {
+        $pipeline = map(static function () use ($input) {
             yield from $input;
-        })->reservoir($size, $weightFn));
+        });
+
+        $this->assertSame($expected, $pipeline->reservoir($size, $weightFn));
+
+        if ($size <= 0) {
+            $this->assertSame([], $pipeline->toArray());
+        }
     }
 
     /**