refactor: Adjust Radio.Group logic that value is undefined should be uncontrolled mode.

components/radio/__tests__/group.test.js

@@ -170,10 +170,35 @@ describe('Radio Group', () => {
   });
 
   it('passes prefixCls down to radio', () => {
-    const options = [{ label: 'Apple', value: 'Apple' }, { label: 'Orange', value: 'Orange', style: { fontSize: 12 } }];
+    const options = [
+      { label: 'Apple', value: 'Apple' },
+      { label: 'Orange', value: 'Orange', style: { fontSize: 12 } },
+    ];
 
     const wrapper = render(<RadioGroup prefixCls="my-radio" options={options} />);
 
     expect(wrapper).toMatchSnapshot();
   });
+
+  describe('value is null or undefined', () => {
+    it('use `defaultValue` when `value` is undefined', () => {
+      const options = [{ label: 'Bamboo', value: 'bamboo' }];
+      const wrapper = mount(
+        <RadioGroup defaultValue="bamboo" value={undefined} options={options} />,
+      );
+
+      expect(wrapper.state().value).toEqual('bamboo');
+    });
+
+    [undefined, null].forEach(newValue => {
+      it(`should set value back when value change back to ${newValue}`, () => {
+        const options = [{ label: 'Bamboo', value: 'bamboo' }];
+        const wrapper = mount(<RadioGroup value="bamboo" options={options} />);
+        expect(wrapper.state().value).toEqual('bamboo');
+
+        wrapper.setProps({ value: newValue });
+        expect(wrapper.state().value).toEqual(newValue);
+      });
+    });
+  });
 });

components/radio/group.tsx

@@ -28,35 +28,37 @@ class RadioGroup extends React.PureComponent<RadioGroupProps, RadioGroupState> {
     buttonStyle: 'outline' as RadioGroupButtonStyle,
   };
 
-  static getDerivedStateFromProps(nextProps: RadioGroupProps) {
-    if ('value' in nextProps) {
-      return {
-        value: nextProps.value,
-      };
-    }
-    const checkedValue = getCheckedValue(nextProps.children);
-    if (checkedValue) {
-      return {
-        value: checkedValue.value,
-      };
+  static getDerivedStateFromProps(nextProps: RadioGroupProps, prevState: RadioGroupState) {
+    const newState: Partial<RadioGroupState> = {
+      prevPropValue: nextProps.value,
+    };
+
+    if (nextProps.value !== undefined || prevState.prevPropValue !== nextProps.value) {
+      newState.value = nextProps.value;
+    } else {
+      const checkedValue = getCheckedValue(nextProps.children);
+      if (checkedValue) {
+        newState.value = checkedValue.value;
+      }
     }
 
-    return null;
+    return newState;
   }
 
   constructor(props: RadioGroupProps) {
     super(props);
     let value;
-    if ('value' in props) {
+    if (props.value !== undefined) {
       value = props.value;
-    } else if ('defaultValue' in props) {
+    } else if (props.defaultValue !== undefined) {
       value = props.defaultValue;
     } else {
       const checkedValue = getCheckedValue(props.children);
       value = checkedValue && checkedValue.value;
     }
     this.state = {
       value,
+      prevPropValue: props.value,
     };
   }
 

components/radio/interface.tsx

@@ -20,6 +20,7 @@ export interface RadioGroupProps extends AbstractCheckboxGroupProps {
 
 export interface RadioGroupState {
   value: any;
+  prevPropValue: any;
 }
 
 export interface RadioGroupContextProps {