Guard against incorrect context use.

Instead of just having random tests fail, fail all the tests with a
slightly more useful message.

Also remove all the code around acquiring and contention, now that
we have a test rule in place for TestableContext, we can just use
that for cleanup and have a simple copy-on-write provider.

Test: runtest -x frameworks/base/tests/testables && runtest systemui
Change-Id: I907da23730a4a96cfa2bb112100a06980f01b078
Fixes: 37302051
diff --git a/tests/testables/src/android/testing/TestableSettingsProvider.java b/tests/testables/src/android/testing/TestableSettingsProvider.java
new file mode 100644
index 0000000..13056cf
--- /dev/null
+++ b/tests/testables/src/android/testing/TestableSettingsProvider.java
@@ -0,0 +1,120 @@
+/*
+ * 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 android.testing;
+
+import android.content.ContentProviderClient;
+import android.content.Context;
+import android.os.Bundle;
+import android.os.RemoteException;
+import android.provider.Settings;
+import android.test.mock.MockContentProvider;
+import android.util.Log;
+
+import java.util.HashMap;
+
+import static org.junit.Assert.*;
+
+/**
+ * Allows calls to android.provider.Settings to be tested easier.
+ *
+ * This provides a simple copy-on-write implementation of settings that gets cleared
+ * at the end of each test.
+ */
+public class TestableSettingsProvider extends MockContentProvider {
+
+    private static final String TAG = "TestableSettingsProvider";
+    private static final boolean DEBUG = false;
+    private static final String MY_UNIQUE_KEY = "Key_" + TestableSettingsProvider.class.getName();
+    private static TestableSettingsProvider sInstance;
+
+    private final ContentProviderClient mSettings;
+
+    private final HashMap<String, String> mValues = new HashMap<>();
+
+    private TestableSettingsProvider(ContentProviderClient settings) {
+        mSettings = settings;
+    }
+
+    void clearValuesAndCheck(Context context) {
+        mValues.put(key("global", MY_UNIQUE_KEY), MY_UNIQUE_KEY);
+        mValues.put(key("secure", MY_UNIQUE_KEY), MY_UNIQUE_KEY);
+        mValues.put(key("system", MY_UNIQUE_KEY), MY_UNIQUE_KEY);
+
+        // Verify that if any test is using TestableContext, they all have the correct settings
+        // provider.
+        assertEquals("Incorrect settings provider, test using incorrect Context?", MY_UNIQUE_KEY,
+                Settings.Global.getString(context.getContentResolver(), MY_UNIQUE_KEY));
+        assertEquals("Incorrect settings provider, test using incorrect Context?", MY_UNIQUE_KEY,
+                Settings.Secure.getString(context.getContentResolver(), MY_UNIQUE_KEY));
+        assertEquals("Incorrect settings provider, test using incorrect Context?", MY_UNIQUE_KEY,
+                Settings.System.getString(context.getContentResolver(), MY_UNIQUE_KEY));
+
+        mValues.clear();
+    }
+
+    public Bundle call(String method, String arg, Bundle extras) {
+        // Methods are "GET_system", "GET_global", "PUT_secure", etc.
+        final String[] commands = method.split("_", 2);
+        final String op = commands[0];
+        final String table = commands[1];
+
+            String k = key(table, arg);
+            String value;
+            Bundle out = new Bundle();
+            switch (op) {
+                case "GET":
+                    if (mValues.containsKey(k)) {
+                        value = mValues.get(k);
+                        if (value != null) {
+                            out.putString(Settings.NameValueTable.VALUE, value);
+                        }
+                    } else {
+                        // Fall through to real settings.
+                        try {
+                            if (DEBUG) Log.d(TAG, "Falling through to real settings " + method);
+                            // TODO: Add our own version of caching to handle this.
+                            Bundle call = mSettings.call(method, arg, extras);
+                            call.remove(Settings.CALL_METHOD_TRACK_GENERATION_KEY);
+                            return call;
+                        } catch (RemoteException e) {
+                            throw new RuntimeException(e);
+                        }
+                    }
+                    break;
+                case "PUT":
+                    value = extras.getString(Settings.NameValueTable.VALUE, null);
+                    mValues.put(k, value);
+                    break;
+                default:
+                    throw new UnsupportedOperationException("Unknown command " + method);
+            }
+            return out;
+    }
+
+    private static String key(String table, String key) {
+        return table + "_" + key;
+    }
+
+    /**
+     * Since the settings provider is cached inside android.provider.Settings, this must
+     * be gotten statically to ensure there is only one instance referenced.
+     */
+    static TestableSettingsProvider getFakeSettingsProvider(ContentProviderClient settings) {
+        if (sInstance == null) {
+            sInstance = new TestableSettingsProvider(settings);
+        }
+        return sInstance;
+    }
+}