Issue #3521698 by alexpott: Add schema for workflow third party settings and test form properly

config/schema/entity_usage_updater.schema.yml

@@ -13,3 +13,10 @@ entity_usage_updater.plugin.html_link:
     convert_to_linkit:
       type: boolean
       label: 'Convert normal links to LinkIt links'
+
+workflows.workflow.*.third_party.entity_usage_updater:
+  type: mapping
+  mapping:
+    default_unpublished_state:
+      type: string
+      label: 'ID of the default unpublished state'

src/Form/SettingsForm.php

@@ -82,6 +82,7 @@ final class SettingsForm extends ConfigFormBase {
           $form['workflow'][$workflow->id()] = [
             '#type' => 'select',
             '#options' => $options,
+            '#default_value' => $workflow->getThirdPartySetting('entity_usage_updater', 'default_unpublished_state'),
             '#title' => $this->t('Select default unpublished state for %label workflow', ['%label' => $workflow->label()]),
           ];
         }

tests/src/Functional/ContentModerationLinkRemoverFormTest.php

@@ -171,6 +171,7 @@ class ContentModerationLinkRemoverFormTest extends ModerationStateTestBase {
       ->pageTextContains('Created Links remover transition.');
 
     $this->drupalGet('admin/config/content/entity-usage-updater');
+    $this->assertSame('archived', $this->assertSession()->fieldExists('workflow[editorial]')->getValue());
     $this->assertCount(2, $this->assertSession()
       ->fieldExists('workflow[editorial]')
       ->findAll('css', 'option'));
@@ -178,6 +179,7 @@ class ContentModerationLinkRemoverFormTest extends ModerationStateTestBase {
       ->fieldExists('workflow[editorial]')
       ->selectOption('links_removed');
     $this->assertSession()->buttonExists('Save')->press();
+    $this->assertSame('links_removed', $this->assertSession()->fieldExists('workflow[editorial]')->getValue());
 
     // Allow the user to use the new transition.
     $role_ids = $this->adminUser->getRoles(TRUE);