diff --git tests/phpunit/tests/comment-submission.php tests/phpunit/tests/comment-submission.php
index 6a5b845bb0..fa40e3490e 100644
--- tests/phpunit/tests/comment-submission.php
+++ tests/phpunit/tests/comment-submission.php
@@ -10,6 +10,7 @@ class Tests_Comment_Submission extends WP_UnitTestCase {
 	protected static $editor_id;
 
 	protected $preprocess_comment_data = array();
+	protected $postprocess_comment_data = array();
 
 	public static function wpSetUpBeforeClass( $factory ) {
 		self::$post = $factory->post->create_and_get();
@@ -752,11 +753,98 @@ class Tests_Comment_Submission extends WP_UnitTestCase {
 
 	}
 
+	/**
+	 * @ticket 49236
+	 */
+	public function test_comment_submission_sends_empty_string_comment_type() {
+		$user = get_userdata( self::$author_id );
+		wp_set_current_user( $user->ID );
+
+		$data = array(
+			'comment_post_ID' => self::$post->ID,
+			'comment'         => 'Comment',
+			'comment_type'    => '',
+		);
+
+		add_filter( 'preprocess_comment', array( $this, 'filter_preprocess_comment' ) );
+
+		$comment = wp_handle_comment_submission( $data );
+
+		remove_filter( 'preprocess_comment', array( $this, 'filter_preprocess_comment' ) );
+
+		$this->assertNotWPError( $comment );
+		$this->assertEquals(
+			array(
+				'comment_post_ID'      => self::$post->ID,
+				'comment_author'       => $user->display_name,
+				'comment_author_email' => $user->user_email,
+				'comment_author_url'   => $user->user_url,
+				'comment_content'      => $data['comment'],
+				'comment_type'         => 'comment',
+				'comment_parent'       => '0',
+				'user_ID'              => $user->ID,
+				'user_id'              => $user->ID,
+			),
+			$this->preprocess_comment_data
+		);
+	}
+
+	/**
+	 * @ticket 49236
+	 */
+	public function test_comment_insertion_uses_empty_string_comment_type() {
+		$user = get_userdata( self::$author_id );
+		wp_set_current_user( $user->ID );
+
+		$data = array(
+			'comment_post_ID'      => self::$post->ID,
+			'comment_author'       => $user->display_name,
+			'comment_author_email' => $user->user_email,
+			'comment_author_url'   => $user->user_url,
+			'comment_content'      => 'Comment',
+			'comment_type'         => '',
+			'user_id'              => $user->ID,
+		);
+
+		add_action( 'wp_insert_comment', array( $this, 'action_postprocess_comment' ), 10, 2 );
+
+		$comment = wp_insert_comment( $data );
+
+		remove_action( 'wp_insert_comment', array( $this, 'action_postprocess_comment' ), 10, 2 );
+
+		$this->assertEquals(
+			array(
+				'comment_post_ID'      => self::$post->ID,
+				'comment_author'       => $data['comment_author'],
+				'comment_author_email' => $data['comment_author_email'],
+				'comment_author_url'   => $data['comment_author_url'],
+				'comment_content'      => $data['comment_content'],
+				'comment_type'         => 'comment',
+				'comment_parent'       => '0',
+				'user_id'              => $data['user_id'],
+			),
+			$this->postprocess_comment_data
+		);
+	}
+
 	public function filter_preprocess_comment( $commentdata ) {
 		$this->preprocess_comment_data = $commentdata;
 		return $commentdata;
 	}
 
+	public function action_postprocess_comment( $id, $comment ) {
+		$this->postprocess_comment_data = array(
+			'comment_post_ID'      => (int) $comment->comment_post_ID,
+			'comment_author'       => $comment->comment_author,
+			'comment_author_email' => $comment->comment_author_email,
+			'comment_author_url'   => $comment->comment_author_url,
+			'comment_content'      => $comment->comment_content,
+			'comment_type'         => $comment->comment_type,
+			'comment_parent'       => $comment->comment_parent,
+			'user_id'              => (int) $comment->user_id,
+		);
+	}
+
 	/**
 	 * @ticket 36901
 	 */