Add code test coverage for a continue statement

Author: Sarthak Jaiswal

plugins/auto-sizes/includes/improve-calculate-sizes.php

@@ -26,7 +26,7 @@ function auto_sizes_prime_attachment_caches( $content ): string {
 		$class = $processor->get_attribute( 'class' );
 
 		if ( ! is_string( $class ) ) {
-			continue; // @codeCoverageIgnore
+			continue;
 		}
 
 		if ( preg_match( '/(?:^|\s)wp-image-([1-9][0-9]*)(?:\s|$)/', $class, $class_id ) === 1 ) {

plugins/auto-sizes/tests/test-improve-calculate-sizes.php

@@ -714,4 +714,18 @@ public function get_group_block_markup( string $content, array $atts = array() )
 		<div class="wp-block-group' . $align_class . '">' . $content . '</div>
 		<!-- /wp:group -->';
 	}
+
+	/**
+	 * Tests the auto_sizes_prime_attachment_caches function.
+	 *
+	 * @covers ::auto_sizes_prime_attachment_caches
+	 */
+	public function test_auto_sizes_prime_attachment_caches_with_empty_class(): void {
+		$img_tag = '<img src="https://example.com/foo.png">';
+
+		$result = auto_sizes_prime_attachment_caches( $img_tag );
+
+		// Assert that the output is the same as the input since no processing should occur.
+		$this->assertSame( $img_tag, $result );
+	}
 }