Fix for rename on non-existing old key - an InvalidPathException is thrown.

json-path/src/main/java/com/jayway/jsonpath/internal/PathRef.java

@@ -2,6 +2,7 @@ package com.jayway.jsonpath.internal;
 
 import com.jayway.jsonpath.Configuration;
 import com.jayway.jsonpath.InvalidModificationException;
+import com.jayway.jsonpath.InvalidPathException;
 import com.jayway.jsonpath.JsonPath;
 import com.jayway.jsonpath.spi.json.JsonProvider;
 
@@ -53,6 +54,9 @@ public abstract class PathRef implements Comparable<PathRef>  {
 
     protected void renameInMap(Object targetMap, String oldKeyName, String newKeyName, Configuration configuration){
         if(configuration.jsonProvider().isMap(targetMap)){
+            if(configuration.jsonProvider().getMapValue(targetMap, oldKeyName) == JsonProvider.UNDEFINED){
+                throw new InvalidPathException("Key "+oldKeyName+" not found in map!");
+            }
             configuration.jsonProvider().setProperty(targetMap, newKeyName, configuration.jsonProvider().getMapValue(targetMap, oldKeyName));
             configuration.jsonProvider().removeProperty(targetMap, oldKeyName);
         } else {

json-path/src/test/java/com/jayway/jsonpath/WriteTest.java

@@ -245,4 +245,9 @@ public class WriteTest extends BaseTest {
     public void multiple_properties_cannot_be_renamed(){
         parse(JSON_DOCUMENT).renameKey("$.store.book[*]['author', 'category']", "old-key", "new-key");
     }
+
+    @Test(expected = InvalidPathException.class)
+    public void non_existent_key_rename_not_allowed(){
+        Object o = parse(JSON_DOCUMENT).renameKey("$", "fake", "new-fake").json();
+    }
 }