Added a benchmark for the bcrypt cost parameter + fixed a unit test

src/Password/Bcrypt.php

@@ -155,4 +155,25 @@ public function getSalt()
 
         return $this->salt;
     }
+
+    /**
+     * Benchmark the bcrypt hash generation to determine the cost parameter
+     * based on time to target. The default time to test is 50 milliseconds
+     * which is a good baseline for systems handling interactive logins.
+     * If you increase the time you will get high cost with better security but
+     * you need to be careful because you can expose your system to DoS attacks.
+     *
+     * @see php.net/manual/en/function.password-hash.php#refsect1-function.password-hash-examples
+     */
+    public function benchmarkCost($timeTarget = 0.05)
+    {
+        $cost = 8;
+        do {
+            $cost++;
+            $start = microtime(true);
+            password_hash("test", PASSWORD_BCRYPT, [ 'cost' => $cost ]);
+            $end = microtime(true);
+        } while (($end - $start) < $timeTarget);
+        return $cost;
+    }
 }

test/Password/BcryptTest.php

@@ -116,4 +116,11 @@ public function testGetSaltError()
     {
         $salt = $this->bcrypt->getSalt();
     }
+
+    public function testBenchmarkCost()
+    {
+        $cost = $this->bcrypt->benchmarkCost();
+        $this->assertInternalType("int", $cost);
+        $this->assertTrue($cost > 8 && $cost < 32);
+    }
 }

test/SymmetricPluginManagerTest.php

@@ -12,6 +12,7 @@
 use Interop\Container\ContainerInterface;
 use Zend\Crypt\SymmetricPluginManager;
 use Zend\Crypt\Symmetric\SymmetricInterface;
+use Zend\Crypt\Symmetric\Exception;
 
 class SymmetricPluginManagerTest extends \PHPUnit_Framework_TestCase
 {
@@ -43,6 +44,9 @@ public function testHas($symmetric)
      */
     public function testGet($symmetric)
     {
+        if (! extension_loaded($symmetric)) {
+            $this->setExpectedException(Exception\RuntimeException::class);
+        }
         $plugin = new SymmetricPluginManager();
         $this->assertInstanceof(SymmetricInterface::class, $plugin->get($symmetric));
     }