feat: add defaultValue for add operation (#52)

Author: kagawagao

src/List.tsx

@@ -11,7 +11,7 @@ interface ListField {
 }
 
 interface ListOperations {
-  add: () => void;
+  add: (defaultValue?: StoreValue) => void;
   remove: (index: number) => void;
   move: (from: number, to: number) => void;
 }
@@ -58,13 +58,13 @@ const List: React.FunctionComponent<ListProps> = ({ name, children }) => {
            * Always get latest value in case user update fields by `form` api.
            */
           const operations: ListOperations = {
-            add: () => {
+            add: defaultValue => {
               // Mapping keys
               keyManager.keys = [...keyManager.keys, keyManager.id];
               keyManager.id += 1;
 
               const newValue = getNewValue();
-              onChange([...newValue, undefined]);
+              onChange([...newValue, defaultValue]);
             },
             remove: (index: number) => {
               const newValue = getNewValue();

tests/list.test.js

@@ -95,23 +95,28 @@ describe('Form.List', () => {
     act(() => {
       operation.add();
     });
+    // Add default value
     act(() => {
-      operation.add();
+      operation.add('2');
     });
+
     act(() => {
       operation.add();
     });
 
     wrapper.update();
     expect(getList().find(Field).length).toEqual(3);
+    expect(form.getFieldsValue()).toEqual({
+      list: [undefined, '2', undefined],
+    });
 
     matchKey(0, '0');
     matchKey(1, '1');
     matchKey(2, '2');
 
     // Move
     act(() => {
-        operation.move(2, 0);
+      operation.move(2, 0);
     });
     wrapper.update();
     matchKey(0, '2');