Adding better error messages for JSON parsing errors

olcut-config-json/src/main/java/com/oracle/labs/mlrg/olcut/config/json/JsonLoader.java

@@ -291,20 +291,26 @@ protected void parseComponent(ObjectNode node) {
                         while (listElementItr.hasNext()) {
                             Entry<String, JsonNode> elementEntry = listElementItr.next();
                             String elementName = elementEntry.getKey();
-                            switch (elementName) {
-                                case ConfigLoader.ITEM:
-                                    listOutput.add(new SimpleProperty(elementEntry.getValue().textValue()));
-                                    break;
-                                case ConfigLoader.TYPE:
-                                    try {
-                                        classListOutput.add(Class.forName(elementEntry.getValue().textValue()));
-                                    } catch (ClassNotFoundException cnfe) {
-                                        throw new ConfigLoaderException("Unable to find class "
-                                                + elementEntry.getValue().textValue() + " in component " + curComponent + ", propertylist " + propName);
-                                    }
-                                    break;
-                                default:
-                                    throw new ConfigLoaderException("Unknown node in component " + curComponent + ", propertylist " + propName + ", node = " + e.getValue().toString());
+                            if (elementEntry.getValue().isTextual()) {
+                                String value = elementEntry.getValue().textValue();
+                                switch (elementName) {
+                                    case ConfigLoader.ITEM:
+                                        listOutput.add(new SimpleProperty(value));
+                                        break;
+                                    case ConfigLoader.TYPE:
+                                        try {
+                                            classListOutput.add(Class.forName(value));
+                                        } catch (ClassNotFoundException cnfe) {
+                                            throw new ConfigLoaderException("Unable to find class "
+                                                    + value + " in component " + curComponent + ", propertylist " + propName);
+                                        }
+                                        break;
+                                    default:
+                                        throw new ConfigLoaderException("Unknown node in component " + curComponent + ", propertylist " + propName + ", node = " + e.getValue().toString());
+                                }
+                            } else {
+                                throw new ConfigLoaderException("Invalid value in component " + curComponent + ", propertylist " + propName + ", node = " + e.getValue().toString() + "" +
+                                        ", all OLCUT property list values must be strings, other types are not parsed.");
                             }
                         }
                     }
@@ -324,13 +330,19 @@ protected void parseComponent(ObjectNode node) {
                         if (mapEntry.getValue().isTextual()) {
                             mapOutput.put(mapEntry.getKey(), new SimpleProperty(mapEntry.getValue().textValue()));
                         } else {
-                            throw new ConfigLoaderException("Unknown node in component " + curComponent + ", propertymap " + propName + ", node = " + e.getValue().toString());
+                            throw new ConfigLoaderException("Invalid value in component " + curComponent + ", propertymap " + propName + ", node = " + e.getValue().toString() +
+                                    ", all OLCUT property map values must be strings, other types are not parsed.");
                         }
                     }
                     rpd.add(propName, new MapProperty(mapOutput));
                 } else {
                     // Generic property.
-                    rpd.add(propName, new SimpleProperty(e.getValue().textValue()));
+                    if (e.getValue().isTextual()) {
+                        rpd.add(propName, new SimpleProperty(e.getValue().textValue()));
+                    } else {
+                        throw new ConfigLoaderException("Invalid value in component " + curComponent + ", property " + propName + ", node = " + e.getValue().toString() +
+                                ", all OLCUT property values must be strings, other types are not parsed.");
+                    }
                 }
             }
         }

olcut-config-json/src/test/java/com/oracle/labs/mlrg/olcut/config/json/test/TypeCheckingTest.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2025, Oracle and/or its affiliates.
+ *
+ * Licensed under the 2-clause BSD license.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package com.oracle.labs.mlrg.olcut.config.json.test;
+
+import com.oracle.labs.mlrg.olcut.config.ConfigurationManager;
+import com.oracle.labs.mlrg.olcut.config.io.ConfigLoaderException;
+import com.oracle.labs.mlrg.olcut.config.json.JsonConfigFactory;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+
+import static com.oracle.labs.mlrg.olcut.config.ConfigurationManager.createModuleResourceString;
+import static org.junit.jupiter.api.Assertions.fail;
+
+public class TypeCheckingTest {
+
+    @BeforeAll
+    public static void setUp() {
+        ConfigurationManager.addFileFormatFactory(new JsonConfigFactory());
+    }
+
+    @Test
+    public void arrayTest() throws IOException {
+        try {
+            ConfigurationManager cm = new ConfigurationManager(createModuleResourceString(this.getClass(), "typeCheckingListConfig.json"));
+            fail("Should have thrown ConfigLoaderException");
+        } catch (ConfigLoaderException e) {
+            Assertions.assertTrue(e.getMessage().startsWith("Invalid value"));
+        }
+    }
+
+    @Test
+    public void propertyTest() throws IOException {
+        try {
+            ConfigurationManager cm = new ConfigurationManager(createModuleResourceString(this.getClass(), "typeCheckingPropertyConfig.json"));
+            fail("Should have thrown ConfigLoaderException");
+        } catch (ConfigLoaderException e) {
+            Assertions.assertTrue(e.getMessage().startsWith("Invalid value"));
+        }
+    }
+
+    @Test
+    public void mapTest() throws IOException {
+        try {
+            ConfigurationManager cm = new ConfigurationManager(createModuleResourceString(this.getClass(), "typeCheckingMapConfig.json"));
+            fail("Should have thrown ConfigLoaderException");
+        } catch (ConfigLoaderException e) {
+            Assertions.assertTrue(e.getMessage().startsWith("Invalid value"));
+        }
+    }
+
+}

olcut-config-json/src/test/resources/com/oracle/labs/mlrg/olcut/config/json/test/typeCheckingListConfig.json

@@ -0,0 +1,62 @@
+{
+  "config" : {
+    "global-properties" : { },
+    "components" : [ {
+      "name" : "a",
+      "type" : "com.oracle.labs.mlrg.olcut.test.config.ArrayConfigurable",
+      "export" : "false",
+      "import" : "false",
+      "properties" : {
+        "floatArray" : [ {
+          "item" : "1.1f"
+        }, {
+          "item" : "2.3"
+        }, {
+          "item" : "3.5"
+        } ],
+        "doubleArray" : [ {
+          "item" : 1e-16
+        }, {
+          "item" : 2e-16
+        }, {
+          "item" : "3.16"
+        } ],
+        "longArray" : [ {
+          "item" : 9223372036854775807
+        }, {
+          "item" : "9223372036854775806"
+        }, {
+          "item" : "5"
+        } ],
+        "byteArray" : [ {
+          "item" : "1"
+        }, {
+          "item" : "2"
+        }, {
+          "item" : "3"
+        } ],
+        "shortArray" : [ {
+          "item" : "1"
+        }, {
+          "item" : "2"
+        }, {
+          "item" : "3"
+        } ],
+        "intArray" : [ {
+          "item" : 1
+        }, {
+          "item" : 2
+        }, {
+          "item": "3"
+        } ],
+        "charArray" : [ {
+          "item" : "a"
+        }, {
+          "item" : "b"
+        }, {
+          "item" : "c"
+        } ]
+      }
+    } ]
+  }
+}

olcut-config-json/src/test/resources/com/oracle/labs/mlrg/olcut/config/json/test/typeCheckingMapConfig.json

@@ -0,0 +1,16 @@
+{
+  "config" : {
+    "components" : [ {
+      "name" : "mapTest",
+      "type" : "com.oracle.labs.mlrg.olcut.test.config.MapConfigurable",
+      "export" : "false",
+      "import" : "false",
+      "properties" : {
+        "map" : {
+          "foo" : "quux",
+          "things" : 5
+        }
+      }
+    } ]
+  }
+}

olcut-config-json/src/test/resources/com/oracle/labs/mlrg/olcut/config/json/test/typeCheckingPropertyConfig.json

@@ -0,0 +1,18 @@
+{
+  "config": {
+    "global-properties": {},
+    "components": [
+      {
+        "name": "a",
+        "type": "com.oracle.labs.mlrg.olcut.test.config.BasicConfigurable",
+        "export": "false",
+        "import": "false",
+        "properties": {
+          "s": "one",
+          "d": 3.0,
+          "i": 2
+        }
+      }
+    ]
+  }
+}