Issue #2561049 by phenaproxima, quietone: Add proper unit tests for the Migration process plugin

core/modules/migrate/src/Plugin/migrate/process/Migration.php

@@ -93,7 +93,7 @@ public function transform($value, MigrateExecutableInterface $migrate_executable
         $source_id_values[$migration_id] = $value;
       }
       // Break out of the loop as soon as a destination ID is found.
-      if ($destination_ids = $migration->getIdMap()->lookupDestinationID($source_id_values[$migration_id])) {
+      if ($destination_ids = $migration->getIdMap()->lookupDestinationId($source_id_values[$migration_id])) {
         break;
       }
     }
@@ -162,7 +162,7 @@ public function transform($value, MigrateExecutableInterface $migrate_executable
    *
    * @throws \Drupal\migrate\MigrateSkipProcessException
    */
-  protected function skipOnEmpty($value) {
+  protected function skipOnEmpty(array $value) {
     if (!array_filter($value)) {
       throw new MigrateSkipProcessException();
     }

core/modules/migrate/tests/src/Unit/process/MigrationTest.php

@@ -2,6 +2,7 @@
 
 namespace Drupal\Tests\migrate\Unit\process;
 
+use Drupal\Core\Entity\EntityStorageInterface;
 use Drupal\migrate\Plugin\MigrationInterface;
 use Drupal\migrate\Plugin\migrate\process\Migration;
 use Drupal\migrate\Plugin\MigrateDestinationInterface;
@@ -86,4 +87,51 @@ public function testTransformWithStubbing() {
     $this->assertEquals(2, $result);
   }
 
+  /**
+   * Tests that processing is skipped when the input value is empty.
+  *
+   * @expectedException \Drupal\migrate\MigrateSkipProcessException
+   */
+  public function testSkipOnEmpty() {
+    $migration_plugin = $this->prophesize(MigrationInterface::class);
+    $migration_plugin_manager = $this->prophesize(MigrationPluginManagerInterface::class);
+    $process_plugin_manager = $this->prophesize(MigratePluginManager::class);
+
+    $configuration = [
+      'migration' => 'foobaz',
+    ];
+    $migration_plugin->id()->willReturn(uniqid());
+    $migration = new Migration($configuration, 'migration', [], $migration_plugin->reveal(), $migration_plugin_manager->reveal(), $process_plugin_manager->reveal());
+    $migration->transform(0, $this->migrateExecutable, $this->row, 'foo');
+  }
+
+  /**
+   * Tests a successful lookup.
+   */
+  public function testSuccessfulLookup() {
+    $migration_plugin = $this->prophesize(MigrationInterface::class);
+    $migration_plugin_manager = $this->prophesize(MigrationPluginManagerInterface::class);
+    $process_plugin_manager = $this->prophesize(MigratePluginManager::class);
+
+    $configuration = [
+      'migration' => 'foobaz',
+    ];
+    $migration_plugin->id()->willReturn(uniqid());
+
+    $id_map = $this->prophesize(MigrateIdMapInterface::class);
+    $id_map->lookupDestinationId([1])->willReturn([3]);
+    $migration_plugin->getIdMap()->willReturn($id_map->reveal());
+
+    $migration_plugin_manager->createInstances(['foobaz'])
+      ->willReturn(['foobaz' => $migration_plugin->reveal()]);
+
+    $migrationStorage = $this->prophesize(EntityStorageInterface::class);
+    $migrationStorage
+      ->loadMultiple(['foobaz'])
+      ->willReturn([$migration_plugin->reveal()]);
+
+    $migration = new Migration($configuration, 'migration', [], $migration_plugin->reveal(), $migration_plugin_manager->reveal(), $process_plugin_manager->reveal());
+    $this->assertSame(3, $migration->transform(1, $this->migrateExecutable, $this->row, 'foo'));
+  }
+
 }