Adding support for DB downgrade

Adding a schema file for handling DB downgrade. This schema file is part of
the backup/restore set, and hence is available on a device with lower app version.

Bug: 37257575
Change-Id: I69c8ef5f28d5209be6e6679412c7459d4eeda5d0

2 files changed, 198 insertions, 0 deletions

diff --git a/tests/res/raw/db_schema_v10.json b/tests/res/raw/db_schema_v10.json
new file mode 100644
index 000000000..a5e290ef7
--- /dev/null
+++ b/tests/res/raw/db_schema_v10.json
@@ -0,0 +1,4 @@
+{
+  "version" : 10,
+  "downgrade_to_9" : []
+}
\ No newline at end of file
diff --git a/tests/src/com/android/launcher3/model/DbDowngradeHelperTest.java b/tests/src/com/android/launcher3/model/DbDowngradeHelperTest.java
new file mode 100644
index 000000000..1d9148ba1
--- /dev/null
+++ b/tests/src/com/android/launcher3/model/DbDowngradeHelperTest.java
@@ -0,0 +1,194 @@
+/*
+ * 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.launcher3.model;
+
+import static junit.framework.Assert.assertEquals;
+import static junit.framework.Assert.assertFalse;
+import static junit.framework.Assert.assertNotSame;
+import static junit.framework.Assert.assertTrue;
+
+import android.content.ContentValues;
+import android.content.Context;
+import android.database.Cursor;
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteOpenHelper;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.filters.SmallTest;
+import android.support.test.runner.AndroidJUnit4;
+
+import com.android.launcher3.LauncherProvider;
+import com.android.launcher3.LauncherProvider.DatabaseHelper;
+import com.android.launcher3.LauncherSettings.Favorites;
+import com.android.launcher3.R;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.io.File;
+
+/**
+ * Tests for {@link DbDowngradeHelper}
+ */
+@SmallTest
+@RunWith(AndroidJUnit4.class)
+public class DbDowngradeHelperTest {
+
+    private static final String SCHEMA_FILE = "test_schema.json";
+    private static final String DB_FILE = "test.db";
+
+    private Context mContext;
+    private File mSchemaFile;
+    private File mDbFile;
+
+    @Before
+    public void setup() {
+        mContext = InstrumentationRegistry.getTargetContext();
+        mSchemaFile = mContext.getFileStreamPath(SCHEMA_FILE);
+        mDbFile = mContext.getDatabasePath(DB_FILE);
+    }
+
+    @Test
+    public void testUpdateSchemaFile() throws Exception {
+        Context myContext = InstrumentationRegistry.getContext();
+        int testResId = myContext.getResources().getIdentifier(
+                "db_schema_v10", "raw", myContext.getPackageName());
+        mSchemaFile.delete();
+        assertFalse(mSchemaFile.exists());
+
+        DbDowngradeHelper.updateSchemaFile(mSchemaFile, 10, myContext, testResId);
+        assertTrue(mSchemaFile.exists());
+        assertEquals(10, DbDowngradeHelper.parse(mSchemaFile).version);
+
+        // Schema is updated on version upgrade
+        assertTrue(mSchemaFile.setLastModified(0));
+        DbDowngradeHelper.updateSchemaFile(mSchemaFile, 11, myContext, testResId);
+        assertNotSame(0, mSchemaFile.lastModified());
+
+        // Schema is not updated when version is same
+        assertTrue(mSchemaFile.setLastModified(0));
+        DbDowngradeHelper.updateSchemaFile(mSchemaFile, 10, myContext, testResId);
+        assertEquals(0, mSchemaFile.lastModified());
+
+        // Schema is not updated on version downgrade
+        DbDowngradeHelper.updateSchemaFile(mSchemaFile, 3, myContext, testResId);
+        assertEquals(0, mSchemaFile.lastModified());
+    }
+
+    @Test
+    public void testDowngrade_success_v24() throws Exception {
+        setupTestDb();
+
+        TestOpenHelper helper = new TestOpenHelper(24);
+        assertEquals(24, helper.getReadableDatabase().getVersion());
+        helper.close();
+    }
+
+    @Test
+    public void testDowngrade_success_v22() throws Exception {
+        setupTestDb();
+
+        SQLiteOpenHelper helper = new TestOpenHelper(22);
+        assertEquals(22, helper.getWritableDatabase().getVersion());
+
+        // Check column does not exist
+        try (Cursor c = helper.getWritableDatabase().query(Favorites.TABLE_NAME,
+                null, null, null, null, null, null)) {
+            assertEquals(-1, c.getColumnIndex(Favorites.OPTIONS));
+
+            // Check data is present
+            assertEquals(10, c.getCount());
+        }
+        helper.close();
+
+        helper = new DatabaseHelper(mContext, null, DB_FILE) {
+            @Override
+            public void onOpen(SQLiteDatabase db) { }
+        };
+        assertEquals(LauncherProvider.SCHEMA_VERSION, helper.getWritableDatabase().getVersion());
+
+        try (Cursor c = helper.getWritableDatabase().query(Favorites.TABLE_NAME,
+                null, null, null, null, null, null)) {
+            // Check column exists
+            assertNotSame(-1, c.getColumnIndex(Favorites.OPTIONS));
+
+            // Check data is present
+            assertEquals(10, c.getCount());
+        }
+        helper.close();
+    }
+
+    @Test(expected = DowngradeFailException.class)
+    public void testDowngrade_fail_v20() throws Exception {
+        setupTestDb();
+
+        TestOpenHelper helper = new TestOpenHelper(20);
+        helper.getReadableDatabase().getVersion();
+    }
+
+    private void setupTestDb() throws Exception {
+        mSchemaFile.delete();
+        mDbFile.delete();
+
+        DbDowngradeHelper.updateSchemaFile(mSchemaFile, LauncherProvider.SCHEMA_VERSION, mContext,
+                R.raw.downgrade_schema);
+
+        DatabaseHelper dbHelper = new DatabaseHelper(mContext, null, DB_FILE) {
+            @Override
+            public void onOpen(SQLiteDatabase db) { }
+        };
+        // Insert dummy data
+        for (int i = 0; i < 10; i++) {
+            ContentValues values = new ContentValues();
+            values.put(Favorites._ID, i);
+            values.put(Favorites.TITLE, "title " + i);
+            dbHelper.getWritableDatabase().insert(Favorites.TABLE_NAME, null, values);
+        }
+        dbHelper.close();
+    }
+
+    private class TestOpenHelper extends SQLiteOpenHelper {
+
+        public TestOpenHelper(int version) {
+            super(mContext, DB_FILE, null, version);
+        }
+
+        @Override
+        public void onCreate(SQLiteDatabase sqLiteDatabase) {
+            throw new RuntimeException("DB should already be created");
+        }
+
+        @Override
+        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+            throw new RuntimeException("Only downgrade supported");
+        }
+
+        @Override
+        public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+            try {
+                DbDowngradeHelper.parse(mSchemaFile).onDowngrade(db, oldVersion, newVersion);
+            } catch (Exception e) {
+                throw new DowngradeFailException(e);
+            }
+        }
+    }
+
+    private static class DowngradeFailException extends RuntimeException {
+        public DowngradeFailException(Exception e) {
+            super(e);
+        }
+    }
+}