Consolidate all wrappers used for testing.

- Add the wrapper package and move all wrappers to the wrapper package.
- Get rid of some wrapper interface/impl implementation and have a
wrapper class directly.

Bug: 65634579
Test: make RunSettingsRoboTests
Change-Id: Ic757d8f7bacfa7a034c7e692205bc1dc4b0e1de1

src/com/android/settings/wrapper/UserManagerWrapper.java

@@ -0,0 +1,44 @@
+/*
+ * 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.wrapper;
+
+import android.content.pm.UserInfo;
+import android.os.UserManager;
+
+import java.util.List;
+
+/**
+ * This class replicates a subset of the android.os.UserManager. The class
+ * exists so that we can use a thin wrapper around the UserManager in production code and a mock in
+ * tests. We cannot directly mock or shadow the UserManager, because some of the methods we rely on
+ * are newer than the API version supported by Robolectric or are hidden.
+ */
+public class UserManagerWrapper {
+    private UserManager mUserManager;
+
+    public UserManagerWrapper(UserManager userManager) {
+        mUserManager = userManager;
+    }
+
+    public UserInfo getPrimaryUser() {
+        return mUserManager.getPrimaryUser();
+    }
+
+    public List<UserInfo> getUsers() {
+        return mUserManager.getUsers();
+    }
+}