Avoid launching captive portal pages when uri is empty

- If uri is empty it will cause ActivityNotFoundException when calling startActivity

Bug: 363782926
Flag: EXEMPT bugfix
Test: Manual testing
atest -c WifiDetailPreferenceController2Test

Change-Id: I48b9a53afe08a7c5e8e512c1961d6aea22a12a21

tests/robotests/src/com/android/settings/wifi/details2/WifiDetailPreferenceController2Test.java

@@ -137,6 +137,7 @@ public class WifiDetailPreferenceController2Test {
     private static final String FACTORY_MAC_ADDRESS = "FACTORY_MAC_ADDRESS";
     private static final String SECURITY = "None";
     private static final String FQDN = "fqdn";
+    private static final Uri TEST_URI = Uri.parse("content://test/test");
 
     @Mock(answer = Answers.RETURNS_DEEP_STUBS)
     private PreferenceScreen mMockScreen;
@@ -1876,6 +1877,24 @@ public class WifiDetailPreferenceController2Test {
         verify(mMockSignalStrengthPref).setTitle(R.string.hotspot_connection_strength);
     }
 
+    @Test
+    public void launchCaptivePortal_uriNull_doNothing() {
+        setUpSpyController();
+
+        mController.launchCaptivePortal(null);
+
+        verify(mContext, never()).startActivity(any());
+    }
+
+    @Test
+    public void launchCaptivePortal_uriNotNull_startActivity() {
+        setUpSpyController();
+
+        mController.launchCaptivePortal(TEST_URI);
+
+        verify(mContext).startActivity(any());
+    }
+
     private SubscriptionInfo mockSubscriptionInfo(int subId, String displayName, int carrierId) {
         SubscriptionInfo info = mock(SubscriptionInfo.class);
         when(info.getSubscriptionId()).thenReturn(subId);