Added URLField definition

Author: srtab

src/Fields/URLField.php

@@ -0,0 +1,28 @@
+<?php
+/**
+ * URLField Class
+ */
+namespace PHPForm\Fields;
+
+use PHPForm\Exceptions\ValidationError;
+use PHPForm\Validators\URLValidator;
+use PHPForm\Widgets\URLInput;
+
+class URLField extends CharField
+{
+    protected $widget = URLInput::class;
+
+    public function __construct(array $args = array())
+    {
+        parent::__construct($args);
+
+        $this->validators[] = new URLValidator();
+    }
+
+    public function toNative($value)
+    {
+        $value = parent::toNative($value);
+
+        return filter_var($value, FILTER_SANITIZE_URL);
+    }
+}

tests/unit/Fields/URLFieldTest.php

@@ -0,0 +1,35 @@
+<?php
+namespace PHPForm\Unit\Fields;
+
+use PHPUnit\Framework\TestCase;
+
+use PHPForm\Exceptions\ValidationError;
+use PHPForm\Fields\URLField;
+use PHPForm\Widgets\URLInput;
+
+class URLFieldTest extends TestCase
+{
+    public function setUp()
+    {
+        $this->field = new URLField();
+    }
+
+    public function testConstruct()
+    {
+        $this->assertInstanceOf(URLInput::class, $this->field->getWidget());
+    }
+
+    /**
+     * @expectedException PHPForm\Exceptions\ValidationError
+     */
+    public function testURLValidator()
+    {
+        $this->field->clean("invalid url");
+    }
+
+    public function testToNative()
+    {
+        $this->assertEquals("invalidurl", $this->field->toNative("invalid url"));
+        $this->assertEquals("invalidrl", $this->field->toNative("invalid úrl"));
+    }
+}