Move field obfuscation into own class

[MAILPOET-1014]

tests/unit/Form/Util/FieldNameObfuscatorTest.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace MailPoet\Form\Util;
+
+class FieldNameObfuscatorTest extends \MailPoetTest {
+
+  public function testObfuscateWorks() {
+    $obfuscator = new FieldNameObfuscator();
+    expect($obfuscator->obfuscate('email'))->notContains('email');
+  }
+
+  public function testObfuscateDeobfuscateWorks() {
+    $obfuscator = new FieldNameObfuscator();
+    $obfuscated = $obfuscator->obfuscate('email');
+    expect($obfuscator->deobfuscate($obfuscated))->equals('email');
+  }
+
+  public function testObfuscatePayloadWorks() {
+    $obfuscator = new FieldNameObfuscator();
+    $obfuscated = $obfuscator->obfuscate('email');
+    $data = array(
+      'regularField' => 'regularValue',
+      $obfuscated => 'obfuscatedFieldValue',
+    );
+    $deobfuscatedPayload = $obfuscator->deobfuscateFormPayload($data);
+    expect($deobfuscatedPayload)->equals(array(
+      'regularField' => 'regularValue',
+      'email' => 'obfuscatedFieldValue',
+    ));
+  }
+}