painless: add trap tests

modules/lang-painless/src/main/resources/org/elasticsearch/painless/java.lang.txt

@@ -1056,6 +1056,7 @@ class ReflectiveOperationException -> java.lang.ReflectiveOperationException ext
 
 class RuntimeException -> java.lang.RuntimeException extends Exception,Object {
   RuntimeException <init>()
+  RuntimeException <init>(String)
 }
 
 class SecurityException -> java.lang.SecurityException extends RuntimeException,Exception,Object {

modules/lang-painless/src/test/java/org/elasticsearch/painless/TryCatchTests.java

@@ -0,0 +1,58 @@
+package org.elasticsearch.painless;
+
+import java.util.Collections;
+
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch 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.
+ */
+
+/** tests for throw/try/catch in painless */
+public class TryCatchTests extends ScriptTestCase {
+
+    /** throws an exception */
+    public void testThrow() {
+        RuntimeException exception = expectThrows(RuntimeException.class, () -> {
+            exec("throw new RuntimeException('test')");
+        });
+        assertEquals("test", exception.getMessage());
+    }
+    
+    /** catches the exact exception */
+    public void testCatch() {
+        assertEquals(1, exec("try { if (params.param == 'true') throw new RuntimeException('test'); } " + 
+                             "catch (RuntimeException e) { return 1; } return 2;", 
+                              Collections.singletonMap("param", "true")));
+    }
+    
+    /** catches superclass of the exception */
+    public void testCatchSuperclass() {
+        assertEquals(1, exec("try { if (params.param == 'true') throw new RuntimeException('test'); } " + 
+                             "catch (Exception e) { return 1; } return 2;", 
+                              Collections.singletonMap("param", "true")));
+    }
+    
+    /** tries to catch a different type of exception */
+    public void testNoCatch() {
+        RuntimeException exception = expectThrows(RuntimeException.class, () -> {
+           exec("try { if (params.param == 'true') throw new RuntimeException('test'); } " + 
+                "catch (ArithmeticException e) { return 1; } return 2;", 
+                Collections.singletonMap("param", "true"));
+        });
+        assertEquals("test", exception.getMessage());
+    }
+}