add more tests

extensions-contrib/kubernetes-overlord-extensions/src/test/java/org/apache/druid/k8s/overlord/RunnerSelectorSpecTest.java

@@ -0,0 +1,33 @@
+/*
+ * 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.druid.k8s.overlord;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class RunnerSelectorSpecTest
+{
+  @Test
+  public void test_whenInvalidDefaultValueConfigured_throwException()
+  {
+    Assert.assertThrows(RuntimeException.class, () -> new RunnerSelectorSpec(null, null));
+    Assert.assertThrows(RuntimeException.class, () -> new RunnerSelectorSpec("unknownRunnerType", null));
+  }
+}