LegacyVpnPreferenceTest added for Vpn settings

Ensure that the profile name is successfully stored, and that the title
of the preference corresponds to the name of the associated VpnProfile

Interesting issue occurred where the icon resource was not present the
first time the class was initialized, but not the second. Trying this
twice within the test resolved this issue.

Test: atest -c LegacyVpnPreferenceTest
Bug: 187245804
Change-Id: I325b155cb0afdb6ce134325944fe5651bf9a1233

tests/unit/src/com/android/settings/vpn2/LegacyVpnPreferenceTest.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2021 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.vpn2;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.mockito.Mockito.spy;
+
+import android.content.Context;
+import android.content.res.Resources.NotFoundException;
+
+import androidx.test.core.app.ApplicationProvider;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+
+import com.android.internal.net.VpnProfile;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+/** Unittest for LegacyVpnPreference */
+@RunWith(AndroidJUnit4.class)
+public class LegacyVpnPreferenceTest {
+    private static final String PROFILE_KEY = "test_key";
+    private static final String PROFILE_NAME = "test_vpn_name";
+
+    private Context mContext;
+    private LegacyVpnPreference mLegacyVpnPreference;
+    private VpnProfile mVpnProfile;
+
+
+    @Before
+    public void setUp() {
+        mContext = spy(ApplicationProvider.getApplicationContext());
+        mVpnProfile = new VpnProfile(PROFILE_KEY);
+        mVpnProfile.name = PROFILE_NAME;
+        try {
+            // In Junit, loading the presference at first yields a Resources.NotFoundException
+            mLegacyVpnPreference = new LegacyVpnPreference(mContext);
+        } catch (NotFoundException exception) {
+            mLegacyVpnPreference = new LegacyVpnPreference(mContext);
+        }
+
+    }
+
+    @Test
+    public void setProfile_successfullyStoresProfile() {
+        mLegacyVpnPreference.setProfile(mVpnProfile);
+        assertThat(mLegacyVpnPreference.getProfile()).isEqualTo(mVpnProfile);
+    }
+
+    @Test
+    public void setProfile_updatesPreferenceTitle() {
+        mLegacyVpnPreference.setProfile(mVpnProfile);
+        assertThat(mLegacyVpnPreference.getTitle()).isEqualTo(PROFILE_NAME);
+    }
+}