Implement proper connection unwrapping.

src/main/java/com/zaxxer/hikari/proxy/ConnectionProxy.java

@@ -429,6 +429,25 @@ public abstract class ConnectionProxy implements IHikariConnectionProxy
         }
     }
 
+    /** {@inheritDoc} */
+    public boolean isWrapperFor(Class<?> iface) throws SQLException
+    {
+        return iface.isInstance(delegate);
+    }
+
+    /** {@inheritDoc} */
+    @SuppressWarnings("unchecked")
+    public <T> T unwrap(Class<T> iface) throws SQLException
+    {
+        if (iface.isInstance(delegate))
+        {
+            return (T) delegate;
+        }
+
+        throw new SQLException("Wrapped connection is not an instance of " + iface);
+    }
+
+
     // **********************************************************************
     //                          Private Methods
     // **********************************************************************

src/test/java/com/zaxxer/hikari/UnwrapTest.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2013 Brett Wooldridge
+ *
+ * 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.zaxxer.hikari;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.zaxxer.hikari.mocks.StubConnection;
+
+/**
+ *
+ * @author Brett Wooldridge
+ */
+public class UnwrapTest
+{
+    @Test
+    public void testUnwrapConnection() throws SQLException
+    {
+        HikariConfig config = new HikariConfig();
+        config.setMinimumPoolSize(1);
+        config.setMaximumPoolSize(1);
+        config.setAcquireIncrement(1);
+        config.setConnectionTestQuery("VALUES 1");
+        config.setDataSourceClassName("com.zaxxer.hikari.mocks.StubDataSource");
+
+        HikariDataSource ds = new HikariDataSource(config);
+
+        Assert.assertSame("Idle connections not as expected", 1, ds.pool.getIdleConnections());
+
+        Connection connection = ds.getConnection();
+        Assert.assertNotNull(connection);
+
+        StubConnection unwrapped = connection.unwrap(StubConnection.class);
+        Assert.assertTrue("unwrapped connection is not instance of StubConnection: " + unwrapped, (unwrapped != null && unwrapped instanceof StubConnection));
+    }
+}