Add submit button renderer test

[MAILPOET-2665]

tests/unit/Form/Block/SubmitTest.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace MailPoet\Test\Form\Block;
+
+use MailPoet\Form\Block\Base;
+use MailPoet\Form\Block\Submit;
+use MailPoet\Test\Form\HtmlParser;
+use PHPUnit\Framework\MockObject\MockObject;
+
+require_once __DIR__ . '/../HtmlParser.php';
+
+class SubmitTest extends \MailPoetUnitTest {
+  /** @var Submit */
+  private $submit;
+
+  /** @var MockObject|Base */
+  private $baseMock;
+
+  /** @var HtmlParser */
+  private $htmlParser;
+
+  private $block = [
+    'type' => 'submit',
+    'name' => 'Submit',
+    'id' => 'submit',
+    'unique' => '1',
+    'static' => '0',
+    'params' => [
+      'label' => 'Submit label',
+    ],
+    'position' => '1',
+  ];
+
+  public function _before() {
+    parent::_before();
+    $this->baseMock = $this->createMock(Base::class);
+    $this->submit = new Submit($this->baseMock);
+    $this->htmlParser = new HtmlParser();
+  }
+
+  public function testItShouldRenderSubmit() {
+    $this->baseMock->expects($this->once())->method('getFieldLabel')->willReturn('Submit label');
+    $html = $this->submit->render($this->block);
+    $input = $this->htmlParser->getElementByXpath($html, '//input');
+    $type = $this->htmlParser->getAttribute($input, 'type');
+    $value = $this->htmlParser->getAttribute($input, 'value');
+    expect($type->value)->equals('submit');
+    expect($value->value)->equals('Submit label');
+  }
+}