refs-test.js

/**
 * Copyright (c) Facebook, Inc. and its 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');
let ReactTestUtils = require('react-dom/test-utils');

/**
 * Counts clicks and has a renders an item for each click. Each item rendered
 * has a ref of the form "clickLogN".
 */
class ClickCounter extends React.Component {
  state = {count: this.props.initialCount};

  triggerReset = () => {
    this.setState({count: this.props.initialCount});
  };

  handleClick = () => {
    this.setState({count: this.state.count + 1});
  };

  render() {
    const children = [];
    let i;
    for (i = 0; i < this.state.count; i++) {
      children.push(
        <div
          className="clickLogDiv"
          key={'clickLog' + i}
          ref={'clickLog' + i}
        />,
      );
    }
    return (
      <span className="clickIncrementer" onClick={this.handleClick}>
        {children}
      </span>
    );
  }
}

/**
 * Only purpose is to test that refs are tracked even when applied to a
 * component that is injected down several layers. Ref systems are difficult to
 * build in such a way that ownership is maintained in an airtight manner.
 */
class GeneralContainerComponent extends React.Component {
  render() {
    return <div>{this.props.children}</div>;
  }
}

/**
 * Notice how refs ownership is maintained even when injecting a component
 * into a different parent.
 */
class TestRefsComponent extends React.Component {
  doReset = () => {
    this.refs.myCounter.triggerReset();
  };

  render() {
    return (
      <div>
        <div ref="resetDiv" onClick={this.doReset}>
          Reset Me By Clicking This.
        </div>
        <GeneralContainerComponent ref="myContainer">
          <ClickCounter ref="myCounter" initialCount={1} />
        </GeneralContainerComponent>
      </div>
    );
  }
}

const expectClickLogsLengthToBe = function(instance, length) {
  const clickLogs = ReactTestUtils.scryRenderedDOMComponentsWithClass(
    instance,
    'clickLogDiv',
  );
  expect(clickLogs.length).toBe(length);
  expect(Object.keys(instance.refs.myCounter.refs).length).toBe(length);
};

describe('reactiverefs', () => {
  let container;

  beforeEach(() => {
    jest.resetModules();
    React = require('react');
    ReactDOM = require('react-dom');
    ReactTestUtils = require('react-dom/test-utils');
  });

  afterEach(() => {
    if (container) {
      document.body.removeChild(container);
      container = null;
    }
  });

  /**
   * Render a TestRefsComponent and ensure that the main refs are wired up.
   */
  const renderTestRefsComponent = function() {
    container = document.createElement('div');
    document.body.appendChild(container);
    const testRefsComponent = ReactDOM.render(<TestRefsComponent />, container);
    expect(testRefsComponent instanceof TestRefsComponent).toBe(true);

    const generalContainer = testRefsComponent.refs.myContainer;
    expect(generalContainer instanceof GeneralContainerComponent).toBe(true);

    const counter = testRefsComponent.refs.myCounter;
    expect(counter instanceof ClickCounter).toBe(true);

    return testRefsComponent;
  };

  /**
   * Ensure that for every click log there is a corresponding ref (from the
   * perspective of the injected ClickCounter component.
   */
  it('Should increase refs with an increase in divs', () => {
    const testRefsComponent = renderTestRefsComponent();
    const clickIncrementer = ReactTestUtils.findRenderedDOMComponentWithClass(
      testRefsComponent,
      'clickIncrementer',
    );

    expectClickLogsLengthToBe(testRefsComponent, 1);

    // After clicking the reset, there should still only be one click log ref.
    testRefsComponent.refs.resetDiv.click();
    expectClickLogsLengthToBe(testRefsComponent, 1);

    // Begin incrementing clicks (and therefore refs).
    clickIncrementer.click();
    expectClickLogsLengthToBe(testRefsComponent, 2);

    clickIncrementer.click();
    expectClickLogsLengthToBe(testRefsComponent, 3);

    // Now reset again
    testRefsComponent.refs.resetDiv.click();
    expectClickLogsLengthToBe(testRefsComponent, 1);
  });
});

describe('factory components', () => {
  it('Should correctly get the ref', () => {
    function Comp() {
      return {
        render() {
          return <div ref="elemRef" />;
        },
      };
    }

    let inst;
    expect(
      () => (inst = ReactTestUtils.renderIntoDocument(<Comp />)),
    ).toWarnDev(
      'Warning: The <Comp /> component appears to be a function component that returns a class instance. ' +
        'Change Comp to a class that extends React.Component instead. ' +
        "If you can't use a class try assigning the prototype on the function as a workaround. " +
        '`Comp.prototype = React.Component.prototype`. ' +
        "Don't use an arrow function since it cannot be called with `new` by React.",
      {withoutStack: true},
    );
    expect(inst.refs.elemRef.tagName).toBe('DIV');
  });
});

/**
 * Tests that when a ref hops around children, we can track that correctly.
 */
describe('ref swapping', () => {
  let RefHopsAround;
  beforeEach(() => {
    jest.resetModules();
    React = require('react');
    ReactDOM = require('react-dom');
    ReactTestUtils = require('react-dom/test-utils');

    RefHopsAround = class extends React.Component {
      state = {count: 0};

      moveRef = () => {
        this.setState({count: this.state.count + 1});
      };

      render() {
        const count = this.state.count;
        /**
         * What we have here, is three divs with refs (div1/2/3), but a single
         * moving cursor ref `hopRef` that "hops" around the three. We'll call the
         * `moveRef()` function several times and make sure that the hop ref
         * points to the correct divs.
         */
        return (
          <div>
            <div
              className="first"
              ref={count % 3 === 0 ? 'hopRef' : 'divOneRef'}
            />
            <div
              className="second"
              ref={count % 3 === 1 ? 'hopRef' : 'divTwoRef'}
            />
            <div
              className="third"
              ref={count % 3 === 2 ? 'hopRef' : 'divThreeRef'}
            />
          </div>
        );
      }
    };
  });

  it('Allow refs to hop around children correctly', () => {
    const refHopsAround = ReactTestUtils.renderIntoDocument(<RefHopsAround />);

    const firstDiv = ReactTestUtils.findRenderedDOMComponentWithClass(
      refHopsAround,
      'first',
    );
    const secondDiv = ReactTestUtils.findRenderedDOMComponentWithClass(
      refHopsAround,
      'second',
    );
    const thirdDiv = ReactTestUtils.findRenderedDOMComponentWithClass(
      refHopsAround,
      'third',
    );

    expect(refHopsAround.refs.hopRef).toEqual(firstDiv);
    expect(refHopsAround.refs.divTwoRef).toEqual(secondDiv);
    expect(refHopsAround.refs.divThreeRef).toEqual(thirdDiv);

    refHopsAround.moveRef();
    expect(refHopsAround.refs.divOneRef).toEqual(firstDiv);
    expect(refHopsAround.refs.hopRef).toEqual(secondDiv);
    expect(refHopsAround.refs.divThreeRef).toEqual(thirdDiv);

    refHopsAround.moveRef();
    expect(refHopsAround.refs.divOneRef).toEqual(firstDiv);
    expect(refHopsAround.refs.divTwoRef).toEqual(secondDiv);
    expect(refHopsAround.refs.hopRef).toEqual(thirdDiv);

    /**
     * Make sure that after the third, we're back to where we started and the
     * refs are completely restored.
     */
    refHopsAround.moveRef();
    expect(refHopsAround.refs.hopRef).toEqual(firstDiv);
    expect(refHopsAround.refs.divTwoRef).toEqual(secondDiv);
    expect(refHopsAround.refs.divThreeRef).toEqual(thirdDiv);
  });

  it('always has a value for this.refs', () => {
    class Component extends React.Component {
      render() {
        return <div />;
      }
    }

    const instance = ReactTestUtils.renderIntoDocument(<Component />);
    expect(!!instance.refs).toBe(true);
  });

  it('ref called correctly for stateless component', () => {
    let refCalled = 0;
    function Inner(props) {
      return <a ref={props.saveA} />;
    }

    class Outer extends React.Component {
      saveA = () => {
        refCalled++;
      };

      componentDidMount() {
        this.setState({});
      }

      render() {
        return <Inner saveA={this.saveA} />;
      }
    }

    ReactTestUtils.renderIntoDocument(<Outer />);
    expect(refCalled).toBe(1);
  });

  it('coerces numbers to strings', () => {
    class A extends React.Component {
      render() {
        return <div ref={1} />;
      }
    }
    const a = ReactTestUtils.renderIntoDocument(<A />);
    expect(a.refs[1].nodeName).toBe('DIV');
  });

  it('provides an error for invalid refs', () => {
    expect(() => {
      ReactTestUtils.renderIntoDocument(<div ref={10} />);
    }).toThrow(
      'Expected ref to be a function, a string, an object returned by React.createRef(), or null.',
    );
    expect(() => {
      ReactTestUtils.renderIntoDocument(<div ref={true} />);
    }).toThrow(
      'Expected ref to be a function, a string, an object returned by React.createRef(), or null.',
    );
    expect(() => {
      ReactTestUtils.renderIntoDocument(<div ref={Symbol('foo')} />);
    }).toThrow(
      'Expected ref to be a function, a string, an object returned by React.createRef(), or null.',
    );
    // This works
    ReactTestUtils.renderIntoDocument(<div ref={undefined} />);
    ReactTestUtils.renderIntoDocument({
      $$typeof: Symbol.for('react.element'),
      type: 'div',
      props: {},
      key: null,
      ref: null,
    });
    // But this doesn't
    expect(() => {
      ReactTestUtils.renderIntoDocument({
        $$typeof: Symbol.for('react.element'),
        type: 'div',
        props: {},
        key: null,
        ref: undefined,
      });
    }).toThrow(
      'Expected ref to be a function, a string, an object returned by React.createRef(), or null.',
    );
  });
});

describe('root level refs', () => {
  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);
  });
});

describe('creating element with ref in constructor', () => {
  class RefTest extends React.Component {
    constructor(props) {
      super(props);
      this.p = <p ref="p">Hello!</p>;
    }

    render() {
      return <div>{this.p}</div>;
    }
  }

  it('throws an error', () => {
    ReactTestUtils = require('react-dom/test-utils');

    expect(function() {
      ReactTestUtils.renderIntoDocument(<RefTest />);
    }).toThrowError(
      'Element ref was specified as a string (p) but no owner was set. This could happen for one of' +
        ' the following reasons:\n' +
        '1. You may be adding a ref to a function component\n' +
        "2. You may be adding a ref to a component that was not created inside a component's render method\n" +
        '3. You have multiple copies of React loaded\n' +
        'See https://fb.me/react-refs-must-have-owner for more information.',
    );
  });
});

describe('strings refs across renderers', () => {
  it('does not break', () => {
    class Parent extends React.Component {
      render() {
        // This component owns both refs.
        return (
          <Indirection
            child1={<div ref="child1" />}
            child2={<div ref="child2" />}
          />
        );
      }
    }

    class Indirection extends React.Component {
      componentDidUpdate() {
        // One ref is being rendered later using another renderer copy.
        jest.resetModules();
        const AnotherCopyOfReactDOM = require('react-dom');
        AnotherCopyOfReactDOM.render(this.props.child2, div2);
      }
      render() {
        // The other one is being rendered directly.
        return this.props.child1;
      }
    }

    const div1 = document.createElement('div');
    const div2 = document.createElement('div');
    const inst = ReactDOM.render(<Parent />, div1);
    // Only the first ref has rendered yet.
    expect(inst.refs.child1.tagName).toBe('DIV');
    expect(inst.refs.child1).toBe(div1.firstChild);

    // Now both refs should be rendered.
    ReactDOM.render(<Parent />, div1);
    expect(inst.refs.child1.tagName).toBe('DIV');
    expect(inst.refs.child1).toBe(div1.firstChild);
    expect(inst.refs.child2.tagName).toBe('DIV');
    expect(inst.refs.child2).toBe(div2.firstChild);
  });
});