explicitly display mysqli error

src/Adapter/Driver/Mysqli/Statement.php

@@ -206,7 +206,10 @@ public function prepare($sql = null)
         $this->resource = $this->mysqli->prepare($sql);
         if (!$this->resource instanceof \mysqli_stmt) {
             throw new Exception\InvalidQueryException(
-                'Statement couldn\'t be produced with sql: ' . $sql,
+                sprintf(
+                    ' Error #%d: %s. Statement couldn\'t be produced with sql: %s', 
+                    $this->mysqli->errno, $this->mysqli->error, $sql
+                ),
                 null,
                 new Exception\ErrorException($this->mysqli->error, $this->mysqli->errno)
             );

test/Adapter/Driver/Mysqli/StatementTest.php

@@ -0,0 +1,56 @@
+<?php
+/**
+ * Zend Framework (http://framework.zend.com/)
+ *
+ * @link      http://github.com/zendframework/zf2 for the canonical source repository
+ * @copyright Copyright (c) 2005-2016 Zend Technologies USA Inc. (http://www.zend.com)
+ * @license   http://framework.zend.com/license/new-bsd New BSD License
+ */
+
+namespace ZendTest\Db\Adapter\Driver\Mysqli;
+
+use Zend\Db\Adapter\Driver\Mysqli\Statement;
+
+use Zend\Db\Adapter\Driver\Mysqli\Connection;
+use Zend\Db\Adapter\Driver\StatementInterface;
+use Zend\Db\Adapter\Exception;
+use Zend\Db\Adapter\ParameterContainer;
+use Zend\Db\Adapter\Profiler;
+
+class MysliTest extends \PHPUnit_Framework_TestCase
+{
+
+    /**
+     * Sets up the fixture, for example, opens a network connection.
+     * This method is called before a test is executed.
+     */
+    protected function setUp()
+    {
+        $this->statement = new Statement();
+    }
+
+    public function testPrepare()
+    {
+        $this->statement->initialize(new TestAsset\MysqliMock());
+        $this->assertNull($this->statement->prepare('SELECT 1'));
+    }
+
+    /**
+     * intentionally throw exception to test error contains valid string
+     */
+    // public function testMysqliStatementPrepareException(){
+    //   $this->statement = new Statement(new Connection());
+    //   // $this->statement->initialize(new mysqli("localhost", "test", "test", "test", 3306));
+
+    //   // $this->_connection = mysqli_connect('localhost', 'root', ''); 
+    //   // $this->_execute('USE playpen');
+    //   $this->statement->setSql('SELECT * FROM test WHERE;');
+    //   try{
+    //     $this->statement->prepare();
+    //   // } catch (InvalidQueryException $e){
+    //   } catch (Exception $e){
+    //     fwrite(STDOUT, $e->getMessage());
+    //   }
+    //   // fwrite(STDOUT, $this->statement->getSql());
+    // }
+}

test/Adapter/Driver/Mysqli/TestAsset/MysqliMock.php

@@ -0,0 +1,23 @@
+<?php
+/**
+ * Zend Framework (http://framework.zend.com/)
+ *
+ * @link      http://github.com/zendframework/zf2 for the canonical source repository
+ * @copyright Copyright (c) 2005-2016 Zend Technologies USA Inc. (http://www.zend.com)
+ * @license   http://framework.zend.com/license/new-bsd New BSD License
+ */
+
+namespace ZendTest\Db\Adapter\Driver\Mysqli\TestAsset;
+
+class MysqliMock extends \mysqli
+{
+    protected $mockStatement;
+
+    public function __construct()
+    {
+        // not sure what to do here
+        // all I really need is mysqli->prepare so line 206 in Statement.php throws the correct exception
+        // $this->resource = $this->mysqli->prepare($sql);
+        parent::__construct();
+    }
+}