Do not allow duplicate element names

kie-yard/kie-yard-core/src/main/java/org/kie/yard/core/YaRDParser.java

@@ -71,8 +71,8 @@ private String read(Reader reader) throws Exception {
         int numRead;
         while ((numRead = reader.read(buf)) != -1) {
             String readData = String.valueOf(buf,
-                                             0,
-                                             numRead);
+                    0,
+                    numRead);
             fileData.append(readData);
             buf = new char[1024];
         }
@@ -92,10 +92,16 @@ private YaRDDefinitions parse(String yaml) throws IOException {
     }
 
     private void appendUnits(List<Element> list) {
+        final List<String> existingNames = new ArrayList<>();
         for (Element hi : list) {
-            String nameString = hi.getName();
+            final String nameString = hi.getName();
+            if (existingNames.contains(nameString)) {
+                throw new IllegalArgumentException("Two element definitions with the same name are not allowed.");
+            } else {
+                existingNames.add(nameString);
+            }
             LOG.debug("parsing {}", nameString);
-            Firable decisionLogic = createDecisionLogic(nameString, hi.getLogic());
+            final Firable decisionLogic = createDecisionLogic(nameString, hi.getLogic());
             definitions.units().add(decisionLogic);
         }
     }

kie-yard/kie-yard-core/src/main/java/org/kie/yard/core/YaRDRunner.java

@@ -25,22 +25,22 @@
 
 public class YaRDRunner {
 
-    private final YaRDDefinitions units;
+    private final YaRDDefinitions definitions;
     private final JsonMapper jsonMapper = JsonMapper.builder().build();
     private final String name;
 
     public YaRDRunner(final String yaml) throws IOException {
         final YaRDParser parser = new YaRDParser(yaml);
         name = parser.getModel().getName();
-        units = parser.getDefinitions();
+        definitions = parser.getDefinitions();
     }
 
     public String getName() {
         return name;
     }
 
     public Map<String, Object> evaluate(final Map<String, Object> map) {
-        return units.evaluate(map);
+        return definitions.evaluate(map);
     }
 
     public String evaluate(String jsonInputCxt) throws Exception {

kie-yard/kie-yard-core/src/test/java/org/kie/yard/core/DublicateElementNameTest.java

@@ -0,0 +1,44 @@
+/*
+ * 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.kie.yard.core;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class DublicateElementNameTest
+        extends TestBase {
+
+    private static final String FILE_NAME = "/two-elements-with-duplicate-name.yml";
+
+    @Test
+    public void testNoDublicateNames() throws Exception {
+        final String CTX = """
+                {
+                    "Age": 10
+                }
+                """;
+        assertThrows(IllegalArgumentException.class, () ->
+                evaluate(CTX, FILE_NAME)
+        );
+    }
+}

kie-yard/kie-yard-core/src/test/java/org/kie/yard/core/MVELJSONTest.java

@@ -57,5 +57,4 @@ public void testMVELManagesJSONMaps() throws Exception {
         final Map mapTest = (Map) output.get("Map Test");
         assertEquals("Hello", mapTest.get("Map"));
     }
-    // TODO Validate two elements can not have the same name
 }

kie-yard/kie-yard-core/src/test/resources/two-elements-with-duplicate-name.yml

@@ -0,0 +1,19 @@
+specVersion: alpha
+kind: YaRD
+name: 'BasePrice'
+inputs:
+  - name: Age
+    type: number
+elements:
+  - name: Ten
+    type: Decision
+    logic:
+      type: LiteralExpression
+      expression: |
+        10
+  - name: Ten
+    type: Decision
+    logic:
+      type: LiteralExpression
+      expression: |
+        5 + 5