add Slf4jFilter testcase

src/test/java/com/alibaba/druid/bvt/filter/Slf4jFilterTest.java

@@ -0,0 +1,38 @@
+package com.alibaba.druid.bvt.filter;
+
+import java.sql.Connection;
+
+import org.junit.Assert;
+
+import junit.framework.TestCase;
+
+import com.alibaba.druid.filter.logging.Slf4jLogFilter;
+import com.alibaba.druid.pool.DruidDataSource;
+import com.alibaba.druid.util.JdbcUtils;
+
+public class Slf4jFilterTest extends TestCase {
+
+    private DruidDataSource dataSource;
+
+    protected void setUp() throws Exception {
+        dataSource = new DruidDataSource();
+
+        dataSource.setUrl("jdbc:mock:xxx");
+        dataSource.setFilters("slf4j");
+        dataSource.setDbType("mysql");
+    }
+
+    protected void tearDown() throws Exception {
+        JdbcUtils.close(dataSource);
+    }
+
+    public void test_slf4j() throws Exception {
+        dataSource.init();
+        
+        Slf4jLogFilter filter = dataSource.unwrap(Slf4jLogFilter.class);
+        Assert.assertNotNull(filter);
+        
+        Connection conn = dataSource.getConnection();
+        conn.close();
+    }
+}