fix init check for mysql

src/main/java/com/alibaba/druid/pool/DruidDataSource.java

@@ -526,8 +526,8 @@ public class DruidDataSource extends DruidAbstractDataSource implements DruidDat
                 this.getConnectProperties().setProperty("oracle.jdbc.FreeMemoryOnEnterImplicitCache", "true");
             }
         } else if (JdbcUtils.MYSQL.equals(this.dbType)) {
-            if (LOG.isWarnEnabled()) {
-                LOG.warn("Your dbType is mysql, recommend set testWhileIdle is true and validationQuery shoud not be null");
+            if (!this.isTestWhileIdle()) {
+                if (LOG.isWarnEnabled()) LOG.warn("Your dbType is mysql, recommend set testWhileIdle is true");
             }
         }
     }

src/test/java/com/alibaba/druid/bvt/pool/ConfigErrorTestMysql.java

@@ -0,0 +1,54 @@
+package com.alibaba.druid.bvt.pool;
+
+import java.lang.reflect.Field;
+
+import junit.framework.Assert;
+import junit.framework.TestCase;
+
+import com.alibaba.druid.pool.DruidDataSource;
+import com.alibaba.druid.support.logging.Log;
+
+public class ConfigErrorTestMysql extends TestCase {
+
+    private DruidDataSource dataSource;
+
+    protected void setUp() throws Exception {
+        dataSource = new DruidDataSource();
+        dataSource.setUrl("jdbc:mysql:xxx");
+        dataSource.setTestOnBorrow(false);
+        dataSource.setInitialSize(0);
+    }
+
+    protected void tearDown() throws Exception {
+        dataSource.close();
+    }
+
+    public void test_success() throws Exception {
+        dataSource.setTestWhileIdle(true);
+
+        Field field = DruidDataSource.class.getDeclaredField("LOG");
+        dataSource.setValidationQuery("select 1");
+        field.setAccessible(true);
+        Log LOG = (Log) field.get(null);
+
+        LOG.resetStat();
+
+        Assert.assertEquals(0, LOG.getWarnCount());
+        dataSource.init();
+        Assert.assertEquals(0, LOG.getWarnCount());
+    }
+
+    public void test_warn() throws Exception {
+        dataSource.setTestWhileIdle(false);
+
+        Field field = DruidDataSource.class.getDeclaredField("LOG");
+        field.setAccessible(true);
+        Log LOG = (Log) field.get(null);
+
+        LOG.resetStat();
+
+        Assert.assertEquals(0, LOG.getWarnCount());
+        dataSource.init();
+        Assert.assertEquals(1, LOG.getWarnCount());
+    }
+}