Fixes for tests

src/database.js

@@ -14,6 +14,7 @@ exports = module.exports = {
 
 var assert = require('assert'),
     async = require('async'),
+    BoxError = require('./boxerror.js'),
     child_process = require('child_process'),
     constants = require('./constants.js'),
     debug = require('debug')('box:database'),
@@ -64,7 +65,7 @@ function initialize(callback) {
         connection.query('SET SESSION sql_mode = \'strict_all_tables\'');
     });
 
-    callback();
+    callback(null);
 }
 
 function uninitialize(callback) {
@@ -85,10 +86,12 @@ function clear(callback) {
 }
 
 function query() {
-    var args = Array.prototype.slice.call(arguments);
-    var callback = args[args.length - 1];
+    const args = Array.prototype.slice.call(arguments);
+    const callback = args[args.length - 1];
     assert.strictEqual(typeof callback, 'function');
 
+    if (constants.TEST && !gConnectionPool) return callback(new BoxError(BoxError.DATABASE_ERROR, 'database.js not initialized'));
+
     gConnectionPool.query.apply(gConnectionPool, args); // this is same as getConnection/query/release
 }