[Wi-Fi] Apply cache in WifiTracker to update the signal icon immediatelly.

issue: Signal icon on the add wifi network feature need to wait for the scan result.
Solution: Apply the cache in the WifiTracker to update signal icon for
shortening the waiting time of new scan result.

Bug: 146842198
Test: Add following unit test cases to test signal level has been updated correctly:
      1. withOneSuggestion_whenScanResultChangedButWifiOff_uiListShouldHaveZeroLevel.

Change-Id: Id72e2b43e020f2cafa2af4af5ffb1c28529002bd

src/com/android/settings/wifi/addappnetworks/AddAppNetworksFragment.java

@@ -715,7 +715,7 @@ public class AddAppNetworksFragment extends InstrumentedFragment implements
     }
 
     @VisibleForTesting
-    void updateScanResults(List<AccessPoint> allAccessPoints) {
+    void updateScanResultsToUi(List<AccessPoint> allAccessPoints) {
         if (mUiToRequestedList == null) {
             // Nothing need to be updated.
             return;
@@ -723,13 +723,16 @@ public class AddAppNetworksFragment extends InstrumentedFragment implements
 
         // Update the signal level of the UI networks.
         for (UiConfigurationItem uiConfigurationItem : mUiToRequestedList) {
-            final Optional<AccessPoint> matchedAccessPoint = allAccessPoints
+            uiConfigurationItem.mLevel = 0;
-                    .stream()
+            if (allAccessPoints != null) {
-                    .filter(accesspoint -> accesspoint.matches(
+                final Optional<AccessPoint> matchedAccessPoint = allAccessPoints
-                            uiConfigurationItem.mWifiNetworkSuggestion.getWifiConfiguration()))
+                        .stream()
-                    .findFirst();
+                        .filter(accesspoint -> accesspoint.matches(
-            uiConfigurationItem.mLevel =
+                                uiConfigurationItem.mWifiNetworkSuggestion.getWifiConfiguration()))
-                    matchedAccessPoint.isPresent() ? matchedAccessPoint.get().getLevel() : 0;
+                        .findFirst();
+                uiConfigurationItem.mLevel =
+                        matchedAccessPoint.isPresent() ? matchedAccessPoint.get().getLevel() : 0;
+            }
         }
 
         if (mIsSingleNetwork) {
@@ -741,8 +744,18 @@ public class AddAppNetworksFragment extends InstrumentedFragment implements
         }
     }
 
+    @Override
+    public void onResume() {
+        super.onResume();
+        onAccessPointsChanged();
+    }
+
+    /**
+     * Update the results when data changes
+     */
     @Override
     public void onAccessPointsChanged() {
-        updateScanResults(mWifiTracker.getAccessPoints());
+        updateScanResultsToUi(
+                mWifiTracker.getManager().isWifiEnabled() ? mWifiTracker.getAccessPoints() : null);
     }
 }

tests/robotests/src/com/android/settings/wifi/addappnetworks/AddAppNetworksFragmentTest.java

@@ -26,6 +26,7 @@ import static org.mockito.Mockito.when;
 
 import android.app.settings.SettingsEnums;
 import android.net.wifi.WifiConfiguration;
+import android.net.wifi.WifiManager;
 import android.net.wifi.WifiNetworkSuggestion;
 import android.os.Bundle;
 import android.os.Parcelable;
@@ -59,7 +60,8 @@ public class AddAppNetworksFragmentTest {
     private static final String FAKE_NEW_SAVED_WPA_SSID = "\"fake_new_wpa_ssid\"";
     private static final String KEY_SSID = "key_ssid";
     private static final String KEY_SECURITY = "key_security";
-    private static final int SCANED_LEVEL = 4;
+    private static final int SCANED_LEVEL0 = 0;
+    private static final int SCANED_LEVEL4 = 4;
 
     private AddAppNetworksFragment mAddAppNetworksFragment;
     private List<WifiNetworkSuggestion> mFakedSpecifiedNetworksList;
@@ -76,6 +78,9 @@ public class AddAppNetworksFragmentTest {
     @Mock
     private WifiTracker mMockWifiTracker;
 
+    @Mock
+    private WifiManager mMockWifiManager;
+
     @Before
     public void setUp() {
         MockitoAnnotations.initMocks(this);
@@ -86,10 +91,13 @@ public class AddAppNetworksFragmentTest {
                 WifiConfiguration.KeyMgmt.NONE, null);
         mSavedWpaConfigurationEntry = generateRegularWifiConfiguration(FAKE_NEW_SAVED_WPA_SSID,
                 WifiConfiguration.KeyMgmt.WPA_PSK, "\"1234567890\"");
+        when(mMockWifiTracker.getManager()).thenReturn(mMockWifiManager);
+        when(mMockWifiManager.isWifiEnabled()).thenReturn(true);
+
         mAddAppNetworksFragment.mWifiTracker = mMockWifiTracker;
         WifiTrackerFactory.setTestingWifiTracker(mMockWifiTracker);
 
-        setUpOneScannedNetworkWithScanedLevel();
+        setUpOneScannedNetworkWithScanedLevel4();
     }
 
     @Test
@@ -208,6 +216,7 @@ public class AddAppNetworksFragmentTest {
     @Test
     public void withOneSuggestion_whenScanResultChanged_uiListShouldHaveNewLevel() {
         // Arrange
+        when(mAddAppNetworksFragment.mWifiTracker.getManager().isWifiEnabled()).thenReturn(true);
         // Setup a fake saved network list and assign to fragment.
         addOneSavedNetworkConfiguration(mSavedWpaConfigurationEntry);
         // Setup one specified networks and its results and assign to fragment.
@@ -221,16 +230,36 @@ public class AddAppNetworksFragmentTest {
 
         // Assert
         assertThat(mAddAppNetworksFragment.mUiToRequestedList.get(0).mLevel).isEqualTo(
-                SCANED_LEVEL);
+                SCANED_LEVEL4);
     }
 
-    private void setUpOneScannedNetworkWithScanedLevel() {
+    @Test
+    public void withOneSuggestion_whenScanResultChangedButWifiOff_uiListShouldHaveZeroLevel() {
+        // Arrange
+        when(mAddAppNetworksFragment.mWifiTracker.getManager().isWifiEnabled()).thenReturn(false);
+        // Setup a fake saved network list and assign to fragment.
+        addOneSavedNetworkConfiguration(mSavedWpaConfigurationEntry);
+        // Setup one specified networks and its results and assign to fragment.
+        addOneSpecifiedRegularNetworkSuggestion(mNewOpenSuggestionEntry);
+        mAddAppNetworksFragment.mAllSpecifiedNetworksList = mFakedSpecifiedNetworksList;
+        // Call filterSavedNetworks to generate necessary objects.
+        mAddAppNetworksFragment.filterSavedNetworks(mFakeSavedNetworksList);
+
+        // Act
+        mAddAppNetworksFragment.onAccessPointsChanged();
+
+        // Assert
+        assertThat(mAddAppNetworksFragment.mUiToRequestedList.get(0).mLevel).isEqualTo(
+                SCANED_LEVEL0);
+    }
+
+    private void setUpOneScannedNetworkWithScanedLevel4() {
         final ArrayList list = new ArrayList<>();
         list.add(mMockAccessPoint);
         when(mMockWifiTracker.getAccessPoints()).thenReturn(list);
         when(mMockAccessPoint.getSsidStr()).thenReturn(FAKE_NEW_OPEN_SSID);
         when(mMockAccessPoint.matches(any(WifiConfiguration.class))).thenReturn(true);
-        when(mMockAccessPoint.getLevel()).thenReturn(SCANED_LEVEL);
+        when(mMockAccessPoint.getLevel()).thenReturn(SCANED_LEVEL4);
     }
 
     private void addOneSavedNetworkConfiguration(@NonNull WifiConfiguration wifiConfiguration) {