Fix bug in DevicePickerFragment

BluetoothProgressCategory will add a no device preference if it is
not scanning and no device is added to the list. Since
DeviceListFragment doesn't report its scanning status correctly, it will
show "No nearby device" even though it is scanning.

This cl add control code for BluetoothProgressCategory in
DeviceListFragment, which avoid the unnecessary no device preference.

Bug: 62492822
Test: RunSettingsRoboTests
Change-Id: Ic49f21cb58a80dcd37c5737800181263ae876ebc

tests/robotests/src/com/android/settings/bluetooth/DevicePickerFragmentTest.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.bluetooth;
+
+import static org.mockito.Mockito.verify;
+
+import com.android.settings.TestConfig;
+import com.android.settings.testutils.SettingsRobolectricTestRunner;
+import com.android.settingslib.bluetooth.LocalBluetoothAdapter;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.robolectric.annotation.Config;
+
+@RunWith(SettingsRobolectricTestRunner.class)
+@Config(manifest = TestConfig.MANIFEST_PATH, sdk = TestConfig.SDK_VERSION)
+public class DevicePickerFragmentTest {
+    @Mock
+    private LocalBluetoothAdapter mLocalAdapter;
+    @Mock
+    private BluetoothProgressCategory mAvailableDevicesCategory;
+    private DevicePickerFragment mFragment;
+
+    @Before
+    public void setUp() {
+        MockitoAnnotations.initMocks(this);
+
+        mFragment = new DevicePickerFragment();
+
+        mFragment.mAvailableDevicesCategory = mAvailableDevicesCategory;
+    }
+
+    @Test
+    public void testScanningStateChanged_started_setProgressStarted() {
+        mFragment.mScanEnabled = true;
+
+        mFragment.onScanningStateChanged(true);
+
+        verify(mAvailableDevicesCategory).setProgress(true);
+    }
+}