Add dirname test (#44491)

Author: alirezasalehizadeh

tests/Support/SupportStringableTest.php

@@ -173,6 +173,20 @@ public function testWhenContainsAll()
             return $stringable->studly();
         }));
     }
+    
+    public function testDirname()
+    {
+        $this->assertSame('/framework/tests', (string) $this->stringable('/framework/tests/Support')->dirname());
+        $this->assertSame('/framework', (string) $this->stringable('/framework/tests/Support')->dirname(2));
+        
+        $this->assertSame('/', (string) $this->stringable('/framework/')->dirname());
+        
+        $this->assertSame('/', (string) $this->stringable('/')->dirname());
+        $this->assertSame('.', (string) $this->stringable('.')->dirname());
+        
+        //  without slash
+        $this->assertSame('.', (string) $this->stringable('framework')->dirname());
+    }
 
     public function testUcsplitOnStringable()
     {