chore: Use unreachable exception in favor of type safety (#22933)

* Use unreachable exception in favor of type safety

* Add tests

* add test

components/_util/__tests__/unreachableException.test.js

@@ -0,0 +1,8 @@
+import UnreachableException from '../unreachableException';
+
+describe('UnreachableException', () => {
+  it('error thrown matches snapshot', () => {
+    const exception = new UnreachableException('some value');
+    expect(exception.message).toMatchInlineSnapshot(`"unreachable case: \\"some value\\""`);
+  });
+});

components/_util/unreachableException.ts

@@ -0,0 +1,5 @@
+export default class UnreachableException {
+  constructor(value: never) {
+    return new Error(`unreachable case: ${JSON.stringify(value)}`);
+  }
+}

components/button/__tests__/__snapshots__/index.test.js.snap

@@ -254,6 +254,12 @@ exports[`Button rtl render component should be rendered correctly in RTL directi
 />
 `;
 
+exports[`Button rtl render component should be rendered correctly in RTL direction 7`] = `
+<div
+  class="ant-btn-group ant-btn-group-rtl"
+/>
+`;
+
 exports[`Button should has click wave effect 1`] = `
 <button
   ant-click-animating-without-extra-node="true"

components/button/__tests__/index.test.js

@@ -15,6 +15,7 @@ describe('Button', () => {
   mountTest(Button.Group);
   mountTest(() => <Button.Group size="large" />);
   mountTest(() => <Button.Group size="small" />);
+  mountTest(() => <Button.Group size="middle" />);
 
   rtlTest(Button);
   rtlTest(() => <Button size="large" />);
@@ -22,6 +23,7 @@ describe('Button', () => {
   rtlTest(Button.Group);
   rtlTest(() => <Button.Group size="large" />);
   rtlTest(() => <Button.Group size="small" />);
+  rtlTest(() => <Button.Group size="middle" />);
 
   it('renders correctly', () => {
     const wrapper = render(<Button>Follow</Button>);
@@ -32,6 +34,16 @@ describe('Button', () => {
     expect(() => renderer.create(<Button>Follow</Button>)).not.toThrow();
   });
 
+  it('warns if size is wrong', () => {
+    const mockWarn = jest.fn();
+    jest.spyOn(console, 'warn').mockImplementation(mockWarn);
+    render(<Button.Group size="who am I" />);
+    expect(mockWarn).toHaveBeenCalledTimes(1);
+    expect(mockWarn.mock.calls[0][0]).toMatchObject({
+      message: 'unreachable case: "who am I"',
+    });
+  });
+
   it('renders Chinese characters correctly', () => {
     const wrapper = render(<Button>按钮</Button>);
     expect(wrapper).toMatchSnapshot();
@@ -189,10 +201,7 @@ describe('Button', () => {
 
   it('should has click wave effect', async () => {
     const wrapper = mount(<Button type="primary">button</Button>);
-    wrapper
-      .find('.ant-btn')
-      .getDOMNode()
-      .click();
+    wrapper.find('.ant-btn').getDOMNode().click();
     await new Promise(resolve => setTimeout(resolve, 0));
     expect(wrapper.render()).toMatchSnapshot();
   });
@@ -265,9 +274,6 @@ describe('Button', () => {
         throw new Error('Should not called!!!');
       },
     });
-    wrapper
-      .find('Button')
-      .instance()
-      .forceUpdate();
+    wrapper.find('Button').instance().forceUpdate();
   });
 });

components/button/button-group.tsx

@@ -2,6 +2,7 @@ import * as React from 'react';
 import classNames from 'classnames';
 import { SizeType } from '../config-provider/SizeContext';
 import { ConfigConsumer, ConfigConsumerProps } from '../config-provider';
+import UnreachableException from '../_util/unreachableException';
 
 export interface ButtonGroupProps {
   size?: SizeType;
@@ -26,8 +27,11 @@ const ButtonGroup: React.FC<ButtonGroupProps> = props => (
         case 'small':
           sizeCls = 'sm';
           break;
-        default:
+        case 'middle':
+        case undefined:
           break;
+        default:
+          console.warn(new UnreachableException(size));
       }
 
       const classes = classNames(