Implement automatic schema upgrading

SchemaVersion subclasses form a DAG, managed by Guice, chaining the
current schema version to its immediate predecessor.  When a version
is selected, we try to upgrade to it by first asking is predecessor
to validate (and upgrade).

Drops of schema elements are not performed automatically, but instead
are printed to the console so the administrator can verify the drops
aren't their own private schema elements, and execute the commands
they know won't damage their own private data.

Change-Id: I2a53749ca23432da2a9b1866203aafb151b48aab
Signed-off-by: Shawn O. Pearce <sop@google.com>

gerrit-server/src/test/java/com/google/gerrit/testutil/TestDatabase.java

@@ -14,12 +14,22 @@
 
 package com.google.gerrit.testutil;
 
+import com.google.gerrit.reviewdb.CurrentSchemaVersion;
 import com.google.gerrit.reviewdb.ReviewDb;
+import com.google.gerrit.reviewdb.SystemConfig;
+import com.google.gerrit.server.config.SystemConfigProvider;
+import com.google.gerrit.server.schema.Current;
 import com.google.gerrit.server.schema.SchemaCreator;
+import com.google.gerrit.server.schema.SchemaVersion;
 import com.google.gwtorm.client.OrmException;
 import com.google.gwtorm.client.SchemaFactory;
 import com.google.gwtorm.jdbc.Database;
 import com.google.gwtorm.jdbc.SimpleDataSource;
+import com.google.inject.Guice;
+import com.google.inject.Key;
+import com.google.inject.Provider;
+
+import junit.framework.TestCase;
 
 import java.io.File;
 import java.sql.Connection;
@@ -57,6 +67,7 @@ public class TestDatabase implements SchemaFactory<ReviewDb> {
   private Connection openHandle;
   private Database<ReviewDb> database;
   private boolean created;
+  private SchemaVersion schemaVersion;
 
   public TestDatabase() throws OrmException {
     try {
@@ -71,6 +82,10 @@ public class TestDatabase implements SchemaFactory<ReviewDb> {
       // Build the access layer around the connection factory.
       //
       database = new Database<ReviewDb>(dataSource, ReviewDb.class);
+
+      schemaVersion =
+          Guice.createInjector(new SchemaVersion.Module()).getBinding(
+              Key.get(SchemaVersion.class, Current.class)).getProvider().get();
     } catch (SQLException e) {
       throw new OrmException(e);
     }
@@ -91,7 +106,7 @@ public class TestDatabase implements SchemaFactory<ReviewDb> {
       created = true;
       final ReviewDb c = open();
       try {
-        new SchemaCreator(new File(".")).create(c);
+        new SchemaCreator(new File("."), schemaVersion).create(c);
       } finally {
         c.close();
       }
@@ -112,4 +127,26 @@ public class TestDatabase implements SchemaFactory<ReviewDb> {
       database = null;
     }
   }
+
+  public SystemConfig getSystemConfig() {
+    return new SystemConfigProvider(this, new Provider<SchemaVersion>() {
+      public SchemaVersion get() {
+        return schemaVersion;
+      }
+    }).get();
+  }
+
+  public CurrentSchemaVersion getSchemaVersion() throws OrmException {
+    final ReviewDb c = open();
+    try {
+      return c.schemaVersion().get(new CurrentSchemaVersion.Key());
+    } finally {
+      c.close();
+    }
+  }
+
+  public void assertSchemaVersion() throws OrmException {
+    final CurrentSchemaVersion act = getSchemaVersion();
+    TestCase.assertEquals(schemaVersion.getVersionNbr(), act.versionNbr);
+  }
 }