fix(strings): fix tests and methods toNull and isNull

Author: Awilum

CHANGELOG.md

@@ -1,3 +1,7 @@
+<a name="4.3.1"></a>
+# [4.3.1](https://github.com/glowyphp/strings) (2022-05-08)
+* Fix toNull() method.
+
 <a name="4.3.0"></a>
 # [4.3.0](https://github.com/glowyphp/strings) (2022-05-08)
 * Added isNull() method.

src/Strings.php

@@ -2138,9 +2138,9 @@ public function toFloat(): float
     /**
      * Return Strings object as null.
      *
-     * @return float Return Strings object as null.
+     * @return null Return Strings object as null.
      */
-    public function toNull(): float
+    public function toNull()
     {
         return null;
     }

tests/StringsTest.php

@@ -867,6 +867,10 @@
     $this->assertTrue(Strings::create('null')->isNull());
 });
 
+test('test toNull() method', function (): void {
+    $this->assertTrue(Strings::create('null')->toNull() === null);
+});
+
 test('test isMAC() method', function (): void {
     $this->assertTrue(Strings::create('00:11:22:33:44:55')->isMAC());
     $this->assertFalse(Strings::create('127.0.0.1')->isMAC());