Issue #2723115 by Stefan Freudenberg, mayurjadhav: Count cache configuration does not work as expected

core/modules/migrate/src/Plugin/migrate/source/SourcePluginBase.php

@@ -143,7 +143,7 @@ abstract class SourcePluginBase extends PluginBase implements MigrateSourceInter
     // Set up some defaults based on the source configuration.
     $this->cacheCounts = !empty($configuration['cache_counts']);
     $this->skipCount = !empty($configuration['skip_count']);
-    $this->cacheKey = !empty($configuration['cache_key']) ? !empty($configuration['cache_key']) : NULL;
+    $this->cacheKey = !empty($configuration['cache_key']) ? $configuration['cache_key'] : NULL;
     $this->trackChanges = !empty($configuration['track_changes']) ? $configuration['track_changes'] : FALSE;
     $this->idMap = $this->migration->getIdMap();
 

core/modules/migrate/tests/src/Unit/MigrateSourceTest.php

@@ -170,6 +170,25 @@ class MigrateSourceTest extends MigrateTestCase {
     $this->assertEquals(-1, $source->count());
   }
 
+   /**
+   * Test that the key can be set for the count cache.
+   *
+   * @covers ::count
+   */
+  public function testCountCacheKey() {
+    // Mock the cache to validate set() receives appropriate arguments.
+    $container = new ContainerBuilder();
+    $cache = $this->getMock(CacheBackendInterface::class);
+    $cache->expects($this->any())->method('set')
+        ->with('test_key', $this->isType('int'), $this->isType('int'));
+    $container->set('cache.migrate', $cache);
+    \Drupal::setContainer($container);
+
+    // Test caching the count with a configured key works.
+    $source = $this->getSource(['cache_counts' => TRUE, 'cache_key' => 'test_key']);
+    $this->assertEquals(1, $source->count());
+  }
+
   /**
    * Test that we don't get a row if prepareRow() is false.
    */