Add token support for alt and title

1. +++ b/src/Plugin/Field/FieldFormatter/SvgFormatter.php
   @@ -128,6 +151,17 @@ class SvgFormatter extends FormatterBase {
   +      '#description' => $this->t('Install token module to see available tokens.'),
   

   we should then unset this description if the token module is installed.

2. +++ b/src/Plugin/Field/FieldFormatter/SvgFormatter.php
   @@ -138,6 +172,23 @@ class SvgFormatter extends FormatterBase {
   +    if ($this->moduleHandler->moduleExists('token')) {
   +      $form['token_help'] = [
   +        '#theme' => 'token_tree_link',
   +        '#token_types' => ['commerce_order'],
   +      ];
   

   the token types that we have are file and the host entity type, e.g. node or media, which you can get from the field definition.

3. +++ b/src/Plugin/Field/FieldFormatter/SvgFormatter.php
   @@ -187,18 +245,27 @@ class SvgFormatter extends FormatterBase {
   -          $attributes['alt'] = $alt;
   +          if ($alt_token = $this->getSetting('alt_token')) {
   +            $alt = $this->token->replace($alt_token, ['file' => $file, $parent->getEntityTypeId() => $parent]);
   +          }
   +          $attributes['alt'] = isset($alt) ? $alt : $default_alt;
   

   you can probably prepare the $data argument once and reuse it.. building it almost costs nothing.

   Also not quite sure.. I think like this, with an isset(), you could also just as well keep the $attributes['alt'] assignment above and overwrite it inside the condition. because it will always at least return an empty string. We should also use the clear option in the third argument, because if a field is empty, we should make sure that we don't display the raw token as the alt title.

   A test would be great, shouldn't be too complicated to create e.g. a media entity with a file and two text fields and then test with some tokens, then test a media with and without text in those fields.

> Added the clear option. The title attribute is still set here though. Not quite sure if we just don't set it or fallback to the auto generated.

I wouldn't fall back, if there's no title then we should skip the alt/title attribute. So maybe it does need to be a bit more complicated again, so we only set it if we have a value:

<?php
$alt = $this->getSetting() ? use-setting : default;
if ($alt) {
$attributes['alt'] = $alt;
}

that said, I'd actually go for a more explicit:

$alt = NULL;
if (use token string) {
$alt = ...;
}
elseif (use fallback) {
$alt = ...;
}

if ($alt) {
// set it
}

Also, maybe use alt_string or something like that instead of token, technically you're not actually required to use a token, can be any string or multiple tokens.

1. +++ b/svg_formatter.info.yml
   @@ -3,3 +3,5 @@ description: 'SVG Formatter provides support for using SVG images on your websit
    core: 8.x
    package: Field types
   +test_dependencies:
   +  - token:token
   

   I'd add a composer.json with require-dev instead. a test_dependencies change needs to be committed first, require-dev works immediately.

2. +++ b/tests/src/Functional/SvgFormatterTest.php
   @@ -0,0 +1,202 @@
   +    $render = $renderer->renderRoot($media_build);
   +    $this->assertTrue(strpos($render, 'thisisthealttext'));
   +    $this->assertTrue(strpos($render, 'thisisthetitletext'));
   +
   +    $media->set('field_alt_string', NULL);
   +    $media->set('field_title_string', NULL);
   +    $media->save();
   +
   +    $media_build = $entity_type_manager->getViewBuilder('media')->view($media, 'default', $component);
   +    /** @var \Drupal\Core\Render\RendererInterface $renderer */
   +    $renderer = \Drupal::service('renderer');
   +    $render = $renderer->renderRoot($media_build);
   +    $this->assertFalse(strpos($render, 'thisisthealttext'));
   +    $this->assertFalse(strpos($render, 'thisisthetitletext'));
   +  }
   

   Can we assert the whole thing? alt="thisisthealttext", so that we can specifically assert that there is no empty alt/title attribute in the second case.

+++ b/tests/src/Functional/SvgFormatterTest.php
@@ -184,8 +185,10 @@ class SvgFormatterTest extends BrowserTestBase {
     /** @var \Drupal\Core\Render\RendererInterface $renderer */
     $renderer = \Drupal::service('renderer');
     $render = $renderer->renderRoot($media_build);
-    $this->assertTrue(strpos($render, 'thisisthealttext'));
-    $this->assertTrue(strpos($render, 'thisisthetitletext'));
+    $dom_document = Html::load($render->__toString());
+    $xpath = new \DOMXPath($dom_document);
+    $this->assertTrue($xpath->query('//div[contains(@class, "field--name-field-media-file")]//img')->item(0)->getAttribute('alt') == 'thisisthealttext');
+    $this->assertTrue($xpath->query('//div[contains(@class, "field--name-field-media-file")]//img')->item(0)->getAttribute('title') == 'thisisthetitletext');
 

Was thinking that it should be easier to write a CSS Based selector for this, but I guess a bit tricky as you render it through the API. I guess you could also switch the setting to allow access to /media/1, then this could be something like this: $this->assertSession()->elementAttributeContains('css', '.field--name-field-media-file img', 'alt', 'thisisthealttext');

(elementNotExists doesn't exist, but you could do $this->assertFalse($this->assertSession()->elementExists('css', '.field--name-field-media-file img')->hasAttribute('title')); for that.

Thanks guys!