Add test cases on ReadwriteSplittingRuleConfiguration (#33577)

* Add more tests on ReadwriteSplittingRuleStatementConverter

* Add test cases on ReadwriteSplittingRuleConfiguration

features/readwrite-splitting/api/src/test/java/org/apache/shardingsphere/readwritesplitting/config/ReadwriteSplittingRuleConfigurationTest.java

@@ -0,0 +1,32 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.shardingsphere.readwritesplitting.config;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Collections;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class ReadwriteSplittingRuleConfigurationTest {
+
+    @Test
+    void assertIsEmpty() {
+        assertTrue(new ReadwriteSplittingRuleConfiguration(Collections.emptyList(), Collections.emptyMap()).isEmpty());
+    }
+}