Fix a bug that relates to creating a new instance using self

composer.json

@@ -14,7 +14,7 @@
   ],
   "config": {
     "platform": {
-      "php": "7.4"
+      "php": "8.0"
     }
   },
   "require-dev": {

psalm.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0"?>
 <psalm
-    phpVersion="7.4"
+    phpVersion="8.0"
     errorLevel="1"
     resolveFromConfigFile="true"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

src/Number/Integer.php

@@ -11,8 +11,9 @@ class Integer extends AbstractType
 {
     private int $value;
 
-    public function __construct(int $value)
+    final public function __construct(int $value)
     {
+        $this->validate($value);
         $this->value = $value;
     }
 
@@ -25,12 +26,17 @@ final public function getValue(): int
      * @param int|float|string $value
      * @return static
      */
-    final public static function fromNumeric($value): self
+    final public static function fromNumeric($value): static
     {
         if (is_numeric($value)) {
-            return new self((int)$value);
+            return new static((int)$value);
         }
 
         throw new InvalidArgumentException('Value is not numeric.');
     }
+
+    protected function validate(int $value): void
+    {
+        // Integer does nothing.
+    }
 }

src/Number/NonNegativeInteger.php

@@ -8,12 +8,10 @@
 
 class NonNegativeInteger extends Integer
 {
-    public function __construct(int $value)
+    protected function validate(int $value): void
     {
         if ($value < 0) {
             throw new InvalidArgumentException('Value must be a non negative integer');
         }
-
-        parent::__construct($value);
     }
 }

src/Number/PositiveInteger.php

@@ -8,12 +8,10 @@
 
 class PositiveInteger extends Integer
 {
-    public function __construct(int $value)
+    protected function validate(int $value): void
     {
         if ($value <= 0) {
             throw new InvalidArgumentException('Value must be a positive integer');
         }
-
-        parent::__construct($value);
     }
 }

tests/Number/NonNegativeIntegerTest.php

@@ -72,4 +72,25 @@ public function test_isNotEqualToDifferentType(): void
         $this->assertFalse($integer1->equals($integer2));
         $this->assertFalse($integer2->equals($integer1));
     }
+
+    public function test_canNotBeCreatedFromNegativeNumericString(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        NonNegativeInteger::fromNumeric('-42');
+    }
+
+    public function test_canNotBeCreatedFromNegativeFloat(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        $result = NonNegativeInteger::fromNumeric(-42.3);
+    }
+
+    public function test_canNotBeCreatedFromNegativeNumeric(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        NonNegativeInteger::fromNumeric(-42);
+    }
 }

tests/Number/PositiveIntegerTest.php

@@ -73,4 +73,32 @@ public function test_isNotEqualToDifferentType(): void
         $this->assertFalse($integer1->equals($integer2));
         $this->assertFalse($integer2->equals($integer1));
     }
+
+    public function test_CannotBeCreatedFromNumericZeroString(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        PositiveInteger::fromNumeric('0');
+    }
+
+    public function test_CannotBeCreatedFromNumericZeroFloat(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        PositiveInteger::fromNumeric(0.0);
+    }
+
+    public function test_CannotBeCreatedFromNumericNegativeIntegerString(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        PositiveInteger::fromNumeric('-1');
+    }
+
+    public function test_CannotBeCreatedFromNumericNegativeInteger(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        PositiveInteger::fromNumeric(-1);
+    }
 }