Fix robo test case failed

Bug: 300134365
Test: robotest
Change-Id: I144fbbc962a479c97312cee1645c5a3d70351542

tests/robotests/src/com/android/settings/widget/HighlightablePreferenceGroupAdapterTest.java

@@ -53,9 +53,13 @@ import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.RuntimeEnvironment;
+import org.robolectric.annotation.Config;
 import org.robolectric.util.ReflectionHelpers;
 
 @RunWith(RobolectricTestRunner.class)
+@Config(shadows = {
+        com.android.settings.testutils.shadow.ShadowFragment.class,
+})
 public class HighlightablePreferenceGroupAdapterTest {
 
     private static final String TEST_KEY = "key";