Improve list display when content is transformed for Mastodon

Fixes #33

includes/post-type-note.php

@@ -488,6 +488,16 @@ function transform_block( array $block ): string {
 				trim( $block['innerHTML'] )
 			)
 		);
+	} elseif ( 'core/list' === $block['blockName'] ) {
+		$list_content = '';
+
+		foreach ( $block['innerBlocks'] as $inner_block ) {
+			$list_content .= transform_block( $inner_block );
+		}
+
+		$content .= rtrim( $list_content, "\n" );
+	} elseif ( 'core/list-item' === $block['blockName'] ) {
+		$content .= '- ' . strip_html( trim( $block['innerHTML'] ) ) . "\n";
 	} else {
 		$content .= strip_html( trim( $block['innerHTML'] ) );
 	}

tests/test-post-type-note.php

@@ -152,6 +152,42 @@ public function test_convert_preformatted_text() {
 		$this->assertEquals( $expected_text, $transformed_text );
 	}
 
+	/**
+	 * A list block should render as text with a dash and a space at the start of each
+	 * list item.
+	 */
+	public function test_convert_list_block() {
+		ob_start();
+		?>
+		<!-- wp:paragraph -->
+<p>This is a list that should be preserved on Mastodon:</p>
+<!-- /wp:paragraph -->
+
+<!-- wp:list -->
+<ul><!-- wp:list-item -->
+<li>Test item one</li>
+<!-- /wp:list-item -->
+
+<!-- wp:list-item -->
+<li>Test item two</li>
+<!-- /wp:list-item -->
+
+<!-- wp:list-item -->
+<li>Test item three</li>
+<!-- /wp:list-item --></ul>
+<!-- /wp:list -->
+
+<!-- wp:paragraph -->
+<p>A dash and a space should be added to the front of each line.</p>
+<!-- /wp:paragraph -->
+		<?php
+		$pre_html         = ob_get_clean();
+		$expected_text    = "This is a list that should be preserved on Mastodon:\n\n- Test item one\n- Test item two\n- Test item three\n\nA dash and a space should be added to the front of each line.";
+		$transformed_text = Note\transform_content( $pre_html );
+
+		$this->assertEquals( $expected_text, $transformed_text );
+	}
+
 	/**
 	 * A single quote block containing a verse block and a citation should
 	 * render as text surrounded with curly quotes, and the link breaks from