Post Template Block: Guard against duplicated block-supports

phpunit/blocks/render-post-template-test.php

@@ -0,0 +1,73 @@
+<?php
+/**
+ * Tests for the Post Template block rendering.
+ *
+ * @package WordPress
+ * @subpackage Blocks
+ * @since 6.0.0
+ *
+ * @group blocks
+ */
+class Tests_Blocks_RenderPostTemplateBlock extends WP_UnitTestCase {
+
+	private static $post;
+	private static $other_post;
+
+	public function set_up() {
+		parent::set_up();
+
+		self::$post = self::factory()->post->create_and_get(
+			array(
+				'post_type'    => 'post',
+				'post_status'  => 'publish',
+				'post_name'    => 'metaldog',
+				'post_title'   => 'Metal Dog',
+				'post_content' => 'Metal Dog content',
+				'post_excerpt' => 'Metal Dog',
+			)
+		);
+
+		self::$other_post = self::factory()->post->create_and_get(
+			array(
+				'post_type'    => 'post',
+				'post_status'  => 'publish',
+				'post_name'    => 'ceilingcat',
+				'post_title'   => 'Ceiling Cat',
+				'post_content' => 'Ceiling Cat content',
+				'post_excerpt' => 'Ceiling Cat',
+			)
+		);
+	}
+
+	public function test_rendering_post_template() {
+		$parsed_blocks = parse_blocks(
+			'<!-- wp:post-template --><!-- wp:post-title /--><!-- wp:post-excerpt /--><!-- /wp:post-template -->'
+		);
+		$block         = new WP_Block( $parsed_blocks[0] );
+		$markup        = $block->render();
+
+		$post_id       = self::$post->ID;
+		$other_post_id = self::$other_post->ID;
+
+		$expected = <<<END
+<ul class="wp-block-post-template is-layout-flow wp-block-post-template-is-layout-flow">
+	<li class="wp-block-post post-$other_post_id post type-post status-publish format-standard hentry category-uncategorized">
+		<h2 class="wp-block-post-title">Ceiling Cat</h2>
+		<div class="wp-block-post-excerpt">
+			<p class="wp-block-post-excerpt__excerpt">Ceiling Cat </p>
+		</div>
+	</li>
+	<li class="wp-block-post post-$post_id post type-post status-publish format-standard hentry category-uncategorized">
+		<h2 class="wp-block-post-title">Metal Dog</h2>
+		<div class="wp-block-post-excerpt">
+			<p class="wp-block-post-excerpt__excerpt">Metal Dog </p>
+		</div>
+	</li>
+</ul>
+END;
+		$this->assertSame(
+			str_replace( array( "\n", "\t" ), '', $expected ),
+			str_replace( array( "\n", "\t" ), '', $markup )
+		);
+	}
+}