--- /dev/null
+<?php
+
+namespace Drupal\paragraphs\Tests\Experimental;
+
+/**
+ * Tests paragraphs duplicate feature.
+ *
+ * @group paragraphs
+ */
+class ParagraphsExperimentalDuplicateFeatureTest extends ParagraphsExperimentalTestBase {
+
+ public static $modules = [
+ 'node',
+ 'paragraphs',
+ 'field',
+ 'field_ui',
+ 'block',
+ 'paragraphs_test',
+ ];
+
+ /**
+ * Tests duplicate paragraph feature.
+ */
+ public function testDuplicateButton() {
+ $this->addParagraphedContentType('paragraphed_test', 'field_paragraphs');
+
+ $this->loginAsAdmin(['create paragraphed_test content', 'edit any paragraphed_test content']);
+ // Add a Paragraph type.
+ $paragraph_type = 'text_paragraph';
+ $this->addParagraphsType($paragraph_type);
+ $this->addParagraphsType('text');
+
+ // Add a text field to the text_paragraph type.
+ static::fieldUIAddNewField('admin/structure/paragraphs_type/' . $paragraph_type, 'text', 'Text', 'text_long', [], []);
+ $this->drupalPostAjaxForm('node/add/paragraphed_test', [], 'field_paragraphs_text_paragraph_add_more');
+
+ // Create a node with a Paragraph.
+ $text = 'recognizable_text';
+ $edit = [
+ 'title[0][value]' => 'paragraphs_mode_test',
+ 'field_paragraphs[0][subform][field_text][0][value]' => $text,
+ ];
+ $this->drupalPostForm(NULL, $edit, t('Save and publish'));
+ $node = $this->drupalGetNodeByTitle('paragraphs_mode_test');
+
+ // Change edit mode to "closed".
+ $this->setParagraphsWidgetMode('paragraphed_test', 'field_paragraphs', 'closed');
+ $this->drupalGet('node/' . $node->id() . '/edit');
+
+ // Click "Duplicate" button.
+ $this->drupalPostAjaxForm(NULL, [], 'field_paragraphs_0_duplicate');
+ $this->drupalPostAjaxForm(NULL, [], 'field_paragraphs_0_edit');
+ $this->assertFieldByName('field_paragraphs[0][subform][field_text][0][value]', $text);
+ $this->assertFieldByName('field_paragraphs[1][subform][field_text][0][value]', $text);
+
+ // Save and check if both paragraphs are present.
+ $this->drupalPostForm(NULL, $edit, t('Save and keep published'));
+ $this->assertNoUniqueText($text);
+ }
+
+ /**
+ * Tests duplicate paragraph feature with nested paragraphs.
+ */
+ public function testDuplicateButtonWithNesting() {
+ $this->addParagraphedContentType('paragraphed_test', 'field_paragraphs');
+
+ $this->loginAsAdmin(['create paragraphed_test content', 'edit any paragraphed_test content']);
+ // Add nested Paragraph type.
+ $nested_paragraph_type = 'nested_paragraph';
+ $this->addParagraphsType($nested_paragraph_type);
+ // Add text Paragraph type.
+ $paragraph_type = 'text';
+ $this->addParagraphsType($paragraph_type);
+
+ // Add a text field to the text_paragraph type.
+ static::fieldUIAddNewField('admin/structure/paragraphs_type/' . $paragraph_type, 'text', 'Text', 'text_long', [], []);
+
+ // Add a ERR paragraph field to the nested_paragraph type.
+ static::fieldUIAddNewField('admin/structure/paragraphs_type/' . $nested_paragraph_type, 'nested', 'Nested', 'field_ui:entity_reference_revisions:paragraph', [
+ 'settings[target_type]' => 'paragraph',
+ 'cardinality' => '-1',
+ ], []);
+ $this->drupalPostAjaxForm('node/add/paragraphed_test', [], 'field_paragraphs_nested_paragraph_add_more');
+
+ // Create a node with a Paragraph.
+ $edit = [
+ 'title[0][value]' => 'paragraphs_mode_test',
+ ];
+ $this->drupalPostForm(NULL, $edit, t('Save and publish'));
+ $node = $this->drupalGetNodeByTitle('paragraphs_mode_test');
+
+ // Add a text field to nested paragraph.
+ $text = 'recognizable_text';
+ $this->drupalPostAjaxForm('node/' . $node->id() . '/edit', [], 'field_paragraphs_0_subform_field_nested_text_add_more');
+ $edit = [
+ 'field_paragraphs[0][subform][field_nested][0][subform][field_text][0][value]' => $text,
+ ];
+ $this->drupalPostForm(NULL, $edit, 'Save and keep published');
+
+ // Switch mode to closed.
+ $this->setParagraphsWidgetMode('paragraphed_test', 'field_paragraphs', 'closed');
+ $this->drupalGet('node/' . $node->id() . '/edit');
+
+ // Click "Duplicate" button.
+ $this->drupalPostAjaxForm(NULL, [], 'field_paragraphs_0_duplicate');
+ $this->drupalPostAjaxForm(NULL, [], 'field_paragraphs_0_edit');
+ $this->assertFieldByName('field_paragraphs[0][subform][field_nested][0][subform][field_text][0][value]', $text);
+ $this->assertFieldByName('field_paragraphs[1][subform][field_nested][0][subform][field_text][0][value]', $text);
+
+ // Change the text paragraph value of duplicated nested paragraph.
+ $second_paragraph_text = 'duplicated_text';
+ $edit = [
+ 'field_paragraphs[1][subform][field_nested][0][subform][field_text][0][value]' => $second_paragraph_text,
+ ];
+
+ // Save and check if the changed text paragraph value of the duplicated
+ // paragraph is not the same as in the original paragraph.
+ $this->drupalPostForm(NULL, $edit, t('Save and keep published'));
+ $this->assertUniqueText($text);
+ $this->assertUniqueText($second_paragraph_text);
+ }
+
+}