fixed testcase

src/main/java/com/alibaba/druid/support/logging/Log.java

@@ -36,6 +36,8 @@ public interface Log {
     void warn(String msg);
 
     void warn(String msg, Throwable e);
+    
+    boolean isErrorEnabled();
 
     int getErrorCount();
 

src/main/java/com/alibaba/druid/support/logging/Log4j2Impl.java

@@ -109,6 +109,10 @@ public class Log4j2Impl implements Log {
     public boolean isWarnEnabled() {
         return log.isEnabled(Level.WARN);
     }
+    
+    public boolean isErrorEnabled() {
+        return log.isErrorEnabled();
+    }
 
     public int getInfoCount() {
         return infoCount;

src/main/java/com/alibaba/druid/support/logging/Log4jImpl.java

@@ -110,6 +110,10 @@ public class Log4jImpl implements Log {
     public boolean isWarnEnabled() {
         return log.isEnabledFor(Level.WARN);
     }
+    
+    public boolean isErrorEnabled() {
+        return log.isEnabledFor(Level.ERROR);
+    }
 
     public int getInfoCount() {
         return infoCount;

src/main/java/com/alibaba/druid/support/logging/NoLoggingImpl.java

@@ -22,6 +22,11 @@ public class NoLoggingImpl implements Log {
     private int    warnCount;
     private int    debugCount;
     private String loggerName;
+    
+    private boolean debugEnable = false;
+    private boolean infoEnable = true;
+    private boolean warnEnable = true;
+    private boolean errorEnable = true;
 
     public NoLoggingImpl(String loggerName){
         this.loggerName = loggerName;
@@ -32,10 +37,14 @@ public class NoLoggingImpl implements Log {
     }
 
     public boolean isDebugEnabled() {
-        return false;
+        return debugEnable;
     }
 
     public void error(String s, Throwable e) {
+        if (!errorEnable) {
+            return;
+        }
+        
         error(s);
 
         if (e != null) {
@@ -86,7 +95,7 @@ public class NoLoggingImpl implements Log {
 
     @Override
     public boolean isInfoEnabled() {
-        return false;
+        return infoEnable;
     }
 
     @Override
@@ -96,7 +105,7 @@ public class NoLoggingImpl implements Log {
 
     @Override
     public boolean isWarnEnabled() {
-        return false;
+        return warnEnable;
     }
 
     public int getInfoCount() {
@@ -107,4 +116,11 @@ public class NoLoggingImpl implements Log {
         return debugCount;
     }
 
+    public boolean isErrorEnabled() {
+        return errorEnable;
+    }
+    
+    public void setErrorEnabled(boolean value) {
+        this.errorEnable = value;
+    }
 }

src/main/java/com/alibaba/druid/support/logging/SLF4JImpl.java

@@ -88,6 +88,11 @@ public class SLF4JImpl implements Log {
     public boolean isWarnEnabled() {
         return log.isWarnEnabled();
     }
+    
+    @Override
+    public boolean isErrorEnabled() {
+        return log.isErrorEnabled();
+    }
 
     @Override
     public void warn(String msg) {

src/main/java/com/alibaba/druid/util/JdbcUtils.java

@@ -357,6 +357,10 @@ public final class JdbcUtils implements JdbcConstants {
     }
 
     public static String getDriverClassName(String rawUrl) throws SQLException {
+        if (rawUrl == null) {
+            return null;
+        }
+        
         if (rawUrl.startsWith("jdbc:derby:")) {
             return "org.apache.derby.jdbc.EmbeddedDriver";
         } else if (rawUrl.startsWith("jdbc:mysql:")) {