Duplicate tests that use legacy features

packages/react-dom/src/__tests__/refsLegacy-test.js

@@ -0,0 +1,101 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @emails react-core
+ */
+
+'use strict';
+
+let React = require('react');
+let ReactDOM = require('react-dom');
+
+describe('root level refs with legacy APIs', () => {
+  beforeEach(() => {
+    jest.resetModules();
+    React = require('react');
+    ReactDOM = require('react-dom');
+  });
+
+  it('attaches and detaches root refs', () => {
+    let inst = null;
+
+    // host node
+    let ref = jest.fn(value => (inst = value));
+    const container = document.createElement('div');
+    let result = ReactDOM.render(<div ref={ref} />, container);
+    expect(ref).toHaveBeenCalledTimes(1);
+    expect(ref.mock.calls[0][0]).toBeInstanceOf(HTMLDivElement);
+    expect(result).toBe(ref.mock.calls[0][0]);
+    ReactDOM.unmountComponentAtNode(container);
+    expect(ref).toHaveBeenCalledTimes(2);
+    expect(ref.mock.calls[1][0]).toBe(null);
+
+    // composite
+    class Comp extends React.Component {
+      method() {
+        return true;
+      }
+      render() {
+        return <div>Comp</div>;
+      }
+    }
+
+    inst = null;
+    ref = jest.fn(value => (inst = value));
+    result = ReactDOM.render(<Comp ref={ref} />, container);
+
+    expect(ref).toHaveBeenCalledTimes(1);
+    expect(inst).toBeInstanceOf(Comp);
+    expect(result).toBe(inst);
+
+    // ensure we have the correct instance
+    expect(result.method()).toBe(true);
+    expect(inst.method()).toBe(true);
+
+    ReactDOM.unmountComponentAtNode(container);
+    expect(ref).toHaveBeenCalledTimes(2);
+    expect(ref.mock.calls[1][0]).toBe(null);
+
+    // fragment
+    inst = null;
+    ref = jest.fn(value => (inst = value));
+    let divInst = null;
+    const ref2 = jest.fn(value => (divInst = value));
+    result = ReactDOM.render(
+      [
+        <Comp ref={ref} key="a" />,
+        5,
+        <div ref={ref2} key="b">
+          Hello
+        </div>,
+      ],
+      container,
+    );
+
+    // first call should be `Comp`
+    expect(ref).toHaveBeenCalledTimes(1);
+    expect(ref.mock.calls[0][0]).toBeInstanceOf(Comp);
+    expect(result).toBe(ref.mock.calls[0][0]);
+
+    expect(ref2).toHaveBeenCalledTimes(1);
+    expect(divInst).toBeInstanceOf(HTMLDivElement);
+    expect(result).not.toBe(divInst);
+
+    ReactDOM.unmountComponentAtNode(container);
+    expect(ref).toHaveBeenCalledTimes(2);
+    expect(ref.mock.calls[1][0]).toBe(null);
+    expect(ref2).toHaveBeenCalledTimes(2);
+    expect(ref2.mock.calls[1][0]).toBe(null);
+
+    // null
+    result = ReactDOM.render(null, container);
+    expect(result).toBe(null);
+
+    // primitives
+    result = ReactDOM.render(5, container);
+    expect(result).toBeInstanceOf(Text);
+  });
+});