Fix robo test case failed

Bug: 300134365
Test: robotest
Change-Id: I144fbbc962a479c97312cee1645c5a3d70351542

tests/robotests/src/com/android/settings/wifi/WifiScanningRequiredFragmentTest.java

@@ -47,8 +47,12 @@ import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.RuntimeEnvironment;
+import org.robolectric.annotation.Config;
 
 @RunWith(RobolectricTestRunner.class)
+@Config(shadows = {
+        com.android.settings.testutils.shadow.ShadowFragment.class,
+})
 public class WifiScanningRequiredFragmentTest {
 
     private WifiScanningRequiredFragment mFragment;