Add a test for the NPE case

Fix: 305784475

Test: unit test
Change-Id: I28b19da80e83bbbddf8a71399fbf706fcbb81a5c
diff --git a/tests/robotests/src/com/android/settings/bluetooth/BluetoothDetailsDataSyncControllerTest.java b/tests/robotests/src/com/android/settings/bluetooth/BluetoothDetailsDataSyncControllerTest.java
index 799f7fc..5d6fe31 100644
--- a/tests/robotests/src/com/android/settings/bluetooth/BluetoothDetailsDataSyncControllerTest.java
+++ b/tests/robotests/src/com/android/settings/bluetooth/BluetoothDetailsDataSyncControllerTest.java
@@ -92,6 +92,14 @@
     }
 
     @Test
+    public void refresh_noAssociations_checkPreferenceInvisible() {
+        mController.mAssociationId = DUMMY_ASSOCIATION_ID;
+        mController.refresh();
+
+        assertThat(mPermSyncPreference.isVisible()).isFalse();
+    }
+
+    @Test
     public void refresh_permSyncNull_checkPreferenceInvisible() {
         mPermissionSyncRequest = null;
         when(mCompanionDeviceManager.getPermissionSyncRequest(ASSOCIATION_ID)).thenReturn(