Support implicit array creation on $append (#127)

Author: fsteeg

metafix/src/main/java/org/metafacture/metafix/FixPath.java

@@ -276,7 +276,16 @@ else if (isReference(field)) {
         }
         else {
             if (!hash.containsField(field)) {
-                hash.put(field, Value.newHash().withPathSet(newValue.getPath()));
+                if (ReservedField.$append.name().equals(tail(path)[0])) {
+                    hash.put(field, Value.newArray().withPathSet(newValue.getPath()));
+                }
+                else {
+                    hash.put(field, Value.newHash().withPathSet(newValue.getPath()));
+                }
+            }
+            final Value value = hash.get(field);
+            if (value.isString()) {
+                hash.put(field, Value.newArray(a -> a.add(value)));
             }
             insertInto(hash.get(field), mode, newValue, field, tail(path));
         }

metafix/src/test/java/org/metafacture/metafix/MetafixRecordTest.java

@@ -303,6 +303,51 @@ public void addWithAppendInNewArray() {
         );
     }
 
+    @Test
+    public void addWithAppendInImplicitArray() {
+        MetafixTestHelpers.assertFix(streamReceiver, Arrays.asList(
+                "add_field('my.name.$append','patrick')",
+                "add_field('my.name.$append','nicolas')"
+            ),
+            i -> {
+                i.startRecord("1");
+                i.endRecord();
+
+                i.startRecord("2");
+                i.startEntity("my");
+                i.literal("name", "max");
+                i.endEntity();
+                i.endRecord();
+
+                i.startRecord("3");
+                i.endRecord();
+            },
+            o -> {
+                o.get().startRecord("1");
+                o.get().startEntity("my");
+                o.get().literal("name", "patrick");
+                o.get().literal("name", "nicolas");
+                o.get().endEntity();
+                o.get().endRecord();
+
+                o.get().startRecord("2");
+                o.get().startEntity("my");
+                o.get().literal("name", "max");
+                o.get().literal("name", "patrick");
+                o.get().literal("name", "nicolas");
+                o.get().endEntity();
+                o.get().endRecord();
+
+                o.get().startRecord("3");
+                o.get().startEntity("my");
+                o.get().literal("name", "patrick");
+                o.get().literal("name", "nicolas");
+                o.get().endEntity();
+                o.get().endRecord();
+            }
+        );
+    }
+
     @Test
     public void addWithAppendInArray() {
         MetafixTestHelpers.assertFix(streamReceiver, Arrays.asList(