Resolve #3495517 "Add further test coverage"

Closes #3495517

tests/modules/page_to_pdf_test/src/Plugin/PdfGenerator/TestPdfGenerator.php

@@ -21,7 +21,7 @@ class TestPdfGenerator extends DoppioPdfGenerator {
   public function generatePdf(string $page_url, string $output_file_uri, array $options = []): void {
     try {
       // Instead of calling the actual API, directly save the mock PDF data.
-      $this->saveMockPdfToFile($output_file_uri);
+      $this->saveMockPdfToFile($output_file_uri, $page_url);
     }
     catch (\Exception $e) {
       $this->logger
@@ -34,8 +34,10 @@ class TestPdfGenerator extends DoppioPdfGenerator {
    *
    * @param string $path
    *   Destination file path.
+   * @param string $page_url
+   *   The page URL.
    */
-  protected function saveMockPdfToFile(string $path): void {
+  protected function saveMockPdfToFile(string $path, string $page_url): void {
     // Mock PDF content.
     $pdf_data = <<<PDF
 %PDF-1.4
@@ -54,7 +56,7 @@ stream
 BT
 /F1 24 Tf
 100 700 Td
-(This is a mock PDF file.) Tj
+(Page URL is "{$page_url}") Tj
 ET
 endstream
 endobj