Allow to correctly compare other values (#89)

Author: akondas

src/Value.php

@@ -10,6 +10,7 @@
 use Munus\Collection\Traversable;
 use Munus\Control\Option;
 use Munus\Control\TryTo;
+use Munus\Value\Comparable;
 use Munus\Value\Comparator;
 
 /**
@@ -21,7 +22,7 @@
  *
  * @template T
  */
-abstract class Value
+abstract class Value implements Comparable
 {
     /**
      * Checks, if the underlying value is absent.

src/Value/Comparable.php

@@ -0,0 +1,10 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Munus\Value;
+
+interface Comparable
+{
+    public function equals(self $other): bool;
+}

src/Value/Comparator.php

@@ -5,7 +5,6 @@
 namespace Munus\Value;
 
 use Munus\Tuple;
-use Munus\Value;
 
 final class Comparator
 {
@@ -15,11 +14,11 @@ final class Comparator
      */
     public static function equals($a, $b): bool
     {
-        if ($a instanceof Value) {
+        if ($a instanceof Comparable) {
             return $a->equals($b);
         }
 
-        if ($b instanceof Value) {
+        if ($b instanceof Comparable) {
             return $b->equals($a);
         }
 

tests/Stub/Event.php

@@ -0,0 +1,19 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Munus\Tests\Stub;
+
+use Munus\Value\Comparable;
+
+final class Event implements Comparable
+{
+    public function __construct(public string $id, public string $name)
+    {
+    }
+
+    public function equals(Comparable $other): bool
+    {
+        return self::class === $other::class && $this->name === $other->name;
+    }
+}

tests/Value/ComparatorTest.php

@@ -5,6 +5,7 @@
 namespace Munus\Tests\Value;
 
 use Munus\Collection\GenericList;
+use Munus\Tests\Stub\Event;
 use Munus\Value\Comparator;
 use PHPUnit\Framework\TestCase;
 
@@ -29,4 +30,14 @@ public function testCompareObjects(): void
         self::assertTrue(Comparator::equals($object3, $object1->append(2)));
         self::assertFalse(Comparator::equals($object1, $object3));
     }
+
+    public function testCompareComparableObject(): void
+    {
+        $event = new Event('123', 'event');
+
+        self::assertTrue(Comparator::equals($event, new Event('456', 'event')));
+        self::assertTrue(Comparator::equals($event, new Event('789', 'event')));
+        self::assertFalse(Comparator::equals($event, new Event('123', 'event1')));
+        self::assertFalse(Comparator::equals($event, new Event('456', 'event1')));
+    }
 }