Encode argument values unambiguously in @cache keys

src/Cache/CacheKeyAndTagsGenerator.php

@@ -37,9 +37,9 @@ public function key(
         ksort($args);
         foreach ($args as $key => $value) {
             $parts[] = $key;
-            $parts[] = is_array($value)
-                ? \Safe\json_encode($value)
-                : $value;
+            $parts[] = is_object($value)
+                ? $value
+                : \Safe\json_encode($value);
         }
 
         return implode(self::SEPARATOR, $parts);

tests/Integration/Cache/CacheDirectiveTest.php

@@ -523,4 +523,66 @@ public function testUseFalsyResultsInCache(): void
             ],
         ]);
     }
+
+    public function testDistinguishesFalseAndNullArgs(): void
+    {
+        $this->mockResolver(static fn (mixed $root, array $args): string => var_export($args['flag'], true));
+
+        $this->schema = /** @lang GraphQL */ <<<'GRAPHQL'
+        type Query {
+            foo(flag: Boolean): String @mock @cache
+        }
+        GRAPHQL;
+
+        $this->graphQL(/** @lang GraphQL */ <<<'GRAPHQL'
+        {
+            foo(flag: false)
+        }
+        GRAPHQL)->assertExactJson([
+            'data' => [
+                'foo' => 'false',
+            ],
+        ]);
+
+        $this->graphQL(/** @lang GraphQL */ <<<'GRAPHQL'
+        {
+            foo(flag: null)
+        }
+        GRAPHQL)->assertExactJson([
+            'data' => [
+                'foo' => 'NULL',
+            ],
+        ]);
+    }
+
+    public function testDistinguishesNullAndStringNullArgs(): void
+    {
+        $this->mockResolver(static fn (mixed $root, array $args): string => var_export($args['arg'], true));
+
+        $this->schema = /** @lang GraphQL */ <<<'GRAPHQL'
+        type Query {
+            foo(arg: String): String @mock @cache
+        }
+        GRAPHQL;
+
+        $this->graphQL(/** @lang GraphQL */ <<<'GRAPHQL'
+        {
+            foo(arg: "null")
+        }
+        GRAPHQL)->assertExactJson([
+            'data' => [
+                'foo' => "'null'",
+            ],
+        ]);
+
+        $this->graphQL(/** @lang GraphQL */ <<<'GRAPHQL'
+        {
+            foo(arg: null)
+        }
+        GRAPHQL)->assertExactJson([
+            'data' => [
+                'foo' => 'NULL',
+            ],
+        ]);
+    }
 }

tests/Unit/Cache/CacheKeyAndTagsGeneratorTest.php

@@ -0,0 +1,69 @@
+<?php declare(strict_types=1);
+
+namespace Tests\Unit\Cache;
+
+use Nuwave\Lighthouse\Cache\CacheKeyAndTagsGenerator;
+use PHPUnit\Framework\TestCase;
+
+final class CacheKeyAndTagsGeneratorTest extends TestCase
+{
+    /** @param  array<string, mixed>  $args */
+    private function key(array $args): string
+    {
+        return (new CacheKeyAndTagsGenerator())->key(
+            user: null,
+            isPrivate: false,
+            parentName: 'Query',
+            id: null,
+            fieldName: 'foo',
+            args: $args,
+            path: ['foo'],
+        );
+    }
+
+    public function testEncodesScalarArgs(): void
+    {
+        $this->assertSame('lighthouse:Query::foo:bar:"baz":first:5', $this->key(['first' => 5, 'bar' => 'baz']));
+    }
+
+    public function testEncodesArrayArgs(): void
+    {
+        $this->assertSame('lighthouse:Query::foo:ids:[1,2]', $this->key(['ids' => [1, 2]]));
+    }
+
+    public function testEncodesStringableArgs(): void
+    {
+        $value = new class implements \Stringable {
+            public function __toString(): string
+            {
+                return 'baz';
+            }
+        };
+
+        $this->assertSame('lighthouse:Query::foo:bar:baz', $this->key(['bar' => $value]));
+    }
+
+    public function testDistinguishesArgsOfDifferentTypes(): void
+    {
+        $keys = [
+            $this->key(['arg' => false]),
+            $this->key(['arg' => null]),
+            $this->key(['arg' => '']),
+            $this->key(['arg' => true]),
+            $this->key(['arg' => 1]),
+            $this->key(['arg' => 1.5]),
+            $this->key(['arg' => 'null']),
+            $this->key(['arg' => 'true']),
+            $this->key(['arg' => 'false']),
+            $this->key(['arg' => '1']),
+            $this->key(['arg' => '1.5']),
+            $this->key(['arg' => '[1]']),
+            $this->key(['arg' => [1]]),
+            $this->key(['arg' => 'a:b:c']),
+            $this->key(['arg' => 'a', 'b' => 'c']),
+            $this->key([]),
+        ];
+
+        $this->assertSame($keys, array_unique($keys));
+    }
+}