Issue #3207907 by quietone, Berdir, alexpott: Ensure functional tests use the test mail collector

(cherry picked from commit 4f043a2e)

core/modules/migrate_drupal_ui/tests/src/Functional/MigrateUpgradeExecuteTestBase.php

@@ -36,6 +36,7 @@ public function doUpgradeAndIncremental() {
     // Test the review form.
     $this->assertReviewForm();
 
+    $this->useTestMailCollector();
     $this->submitForm([], 'Perform upgrade');
     $this->assertUpgrade($this->getEntityCounts());
 
@@ -57,4 +58,16 @@ public function doUpgradeAndIncremental() {
     $this->assertUpgrade($this->getEntityCountsIncremental());
   }
 
+  /**
+   * Helper to set the test mail collector in settings.php.
+   */
+  public function useTestMailCollector() {
+    // Set up an override.
+    $settings['config']['system.mail']['interface']['default'] = (object) [
+      'value' => 'test_mail_collector',
+      'required' => TRUE,
+    ];
+    $this->writeSettings($settings);
+  }
+
 }

core/modules/migrate_drupal_ui/tests/src/Functional/MigrateUpgradeTestBase.php

@@ -357,4 +357,14 @@ protected function assertFileMigrations() {
     }
   }
 
+  /**
+   * Confirm emails were sent.
+   */
+  protected function assertEmailsSent() {
+    // There should be one user activation email.
+    $captured_emails = \Drupal::state()->get('system.test_mail_collector', []);
+    $this->assertCount(1, $captured_emails);
+    $this->assertEquals('user_status_activated', $captured_emails[0]['id']);
+  }
+
 }

core/modules/migrate_drupal_ui/tests/src/Functional/d6/Upgrade6Test.php

@@ -206,6 +206,8 @@ public function testUpgradeAndIncremental() {
     $this->assertUserLogIn(2, 'john.doe_pass');
 
     $this->assertFollowUpMigrationResults();
+
+    $this->assertEmailsSent();
   }
 
   /**

core/modules/migrate_drupal_ui/tests/src/Functional/d7/DoubleSlashTest.php

@@ -61,6 +61,7 @@ public function testMigrateUpgradeExecute() {
     $this->submitForm([], 'Continue');
     $this->submitForm($edits, 'Review upgrade');
     $this->submitForm([], 'I acknowledge I may lose data. Continue anyway.');
+    $this->useTestMailCollector();
     $this->submitForm([], 'Perform upgrade');
 
     // Tests the migration log contains an error message.

core/modules/migrate_drupal_ui/tests/src/Functional/d7/Upgrade7Test.php

@@ -230,6 +230,8 @@ public function testUpgradeAndIncremental() {
     $this->assertUserLogIn(2, 'a password');
 
     $this->assertFollowUpMigrationResults();
+
+    $this->assertEmailsSent();
   }
 
   /**