Improve PerfectHasher and its coverage

src/Internal/PerfectHasher.php

@@ -49,7 +49,7 @@ public static function global(): self
     private \Closure $defaultObjectHasher;
 
     /**
-     * @var array<non-empty-string, callable(object, self): non-empty-string>
+     * @var array<non-empty-string, \Closure(object, self): non-empty-string>
      */
     private array $objectHashers = [];
 
@@ -110,7 +110,7 @@ public function hash(mixed $value): int|string
         }
 
         if (\is_object($value)) {
-            return $this->objectHashes[$value] ??= $this->hashObject($value);
+            return $this->objectHashes[$value] ??= $this->objectHasher($value::class)($value, $this);
         }
 
         if ($value === null) {
@@ -153,28 +153,27 @@ public function hash(mixed $value): int|string
     }
 
     /**
-     * @return non-empty-string
+     * @param class-string $class
+     * @return \Closure(object, self): non-empty-string
      */
-    private function hashObject(object $object): string
+    private function objectHasher(string $class): \Closure
     {
-        $class = $object::class;
-
         if (isset($this->objectHashers[$class])) {
-            return $this->objectHashers[$class]($object, $this);
+            return $this->objectHashers[$class];
         }
 
         foreach (class_parents($class) as $parent) {
             if (isset($this->objectHashers[$parent])) {
-                return ($this->objectHashers[$class] = $this->objectHashers[$parent])($object, $this);
+                return $this->objectHashers[$class] = $this->objectHashers[$parent];
             }
         }
 
         foreach (class_implements($class) as $interface) {
             if (isset($this->objectHashers[$interface])) {
-                return ($this->objectHashers[$class] = $this->objectHashers[$interface])($object, $this);
+                return $this->objectHashers[$class] = $this->objectHashers[$interface];
             }
         }
 
-        return ($this->objectHashers[$class] = $this->defaultObjectHasher)($object);
+        return $this->objectHashers[$class] = $this->defaultObjectHasher;
     }
 }

tests/Internal/PerfectHasherTest.php

@@ -60,7 +60,7 @@ public function testObject(): void
         self::assertSame('#' . spl_object_id($this), $hash);
     }
 
-    public function testObjectWithCustomEncoder(): void
+    public function testObjectWithCustomNormalizer(): void
     {
         $hasher = new PerfectHasher();
         $hasher->registerObjectNormalizer(\Throwable::class, static fn(\Throwable $exception): string => $exception->getMessage());
@@ -74,14 +74,49 @@ public function testObjectWithCustomEncoder(): void
         self::assertSame('RangeException|UnexpectedValueException@`unexpected_value`', $hasher->hash(new \UnexpectedValueException('unexpected_value')));
     }
 
+    public function testObjectHashIsMemoizedForSameInstance(): void
+    {
+        $hasher = new PerfectHasher();
+        $hasher->registerObjectNormalizer(\stdClass::class, static function (): int {
+            static $hash = 0;
+
+            return $hash++;
+        });
+        $object = new \stdClass();
+
+        $hash1 = $hasher->hash($object);
+        $hash2 = $hasher->hash($object);
+
+        self::assertSame('stdClass@0', $hash1);
+        self::assertSame('stdClass@0', $hash2);
+    }
+
+    public function testMemoizedObjectHashIsNotSameForDifferentInstancesOfTheSameClass(): void
+    {
+        $hasher = new PerfectHasher();
+        $hasher->registerObjectNormalizer(\stdClass::class, static function (): int {
+            static $hash = 0;
+
+            return $hash++;
+        });
+        $object1 = new \stdClass();
+        $object2 = clone $object1;
+
+        $hash1 = $hasher->hash($object1);
+        $hash2 = $hasher->hash($object2);
+
+        self::assertSame('stdClass@0', $hash1);
+        self::assertSame('stdClass@1', $hash2);
+    }
+
     /**
      * @param non-empty-string $prefix
      */
     #[TestWith(['abc'])]
     #[TestWith([self::class])]
     #[TestWith(['123'])]
     #[TestWith(['a.b.c'])]
-    public function testRegisterObjectEncoderAcceptsValidPrefix(string $prefix): void
+    public function testRegisterObjectNormalizerAcceptsValidPrefix(string $prefix): void
     {
         $hasher = new PerfectHasher();
 
@@ -98,7 +133,7 @@ public function testRegisterObjectEncoderAcceptsValidPrefix(string $prefix): voi
     #[TestWith(['#'])]
     #[TestWith(['@'])]
     #[TestWith([','])]
-    public function testRegisterObjectEncoderThrowsOnInvalidPrefix(string $prefix): void
+    public function testRegisterObjectNormalizerThrowsOnInvalidPrefix(string $prefix): void
     {
         $hasher = new PerfectHasher();
 
@@ -107,7 +142,7 @@ public function testRegisterObjectEncoderThrowsOnInvalidPrefix(string $prefix):
         $hasher->registerObjectNormalizer(self::class, static fn(): bool => true, $prefix);
     }
 
-    public function testRegisterObjectEncoderThrowsAfterEncoding(): void
+    public function testRegisterObjectNormalizerThrowsAfterHashing(): void
     {
         $hasher = new PerfectHasher();
         $hasher->hash(1);