resolve merge conflict

.eslintrc.js

@@ -9,7 +9,10 @@ const OFF = 0;
 const ERROR = 2;
 
 module.exports = {
-  extends: 'fbjs',
+  extends: [
+    'fbjs',
+    'prettier'
+  ],
 
   // Stop ESLint from looking for a configuration file in parent folders
   root: true,
@@ -30,7 +33,6 @@ module.exports = {
   rules: {
     'accessor-pairs': OFF,
     'brace-style': [ERROR, '1tbs'],
-    'comma-dangle': [ERROR, 'always-multiline'],
     'consistent-return': OFF,
     'dot-location': [ERROR, 'property'],
     // We use console['error']() as a signal to not transform it:

.github/ISSUE_TEMPLATE.md

@@ -1,14 +1,4 @@
-<!--
-  Note: if the issue is about documentation or the website, please file it at:
-  https://github.com/reactjs/reactjs.org/issues/new
--->
+👉 Please follow one of these issue templates:
+- https://github.com/facebook/react/issues/new/choose
 
-**Do you want to request a *feature* or report a *bug*?**
-
-**What is the current behavior?**
-
-**If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem. Your bug will get fixed much faster if we can run your code and it doesn't have dependencies other than React. Paste the link to your JSFiddle (https://jsfiddle.net/Luktwrdm/) or CodeSandbox (https://codesandbox.io/s/new) example below:**
-
-**What is the expected behavior?**
-
-**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**
+Note: to keep the backlog clean and actionable, issues may be immediately closed if they do not follow one of the above issue templates.

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,41 @@
+---
+name: "🐛 Bug Report"
+about: Report a reproducible bug or regression.
+title: 'Bug: '
+labels: 'Status: Unconfirmed'
+
+---
+
+<!--
+  Please provide a clear and concise description of what the bug is. Include
+  screenshots if needed. Please test using the latest version of the relevant
+  React packages to make sure your issue has not already been fixed.
+-->
+
+React version:
+
+## Steps To Reproduce
+
+1.
+2.
+
+<!--
+  Your bug will get fixed much faster if we can run your code and it doesn't
+  have dependencies other than React. Issues without reproduction steps or
+  code examples may be immediately closed as not actionable.
+-->
+
+Link to code example:
+
+<!--
+  Please provide a CodeSandbox (https://codesandbox.io/s/new), a link to a
+  repository on GitHub, or provide a minimal code example that reproduces the
+  problem. You may provide a screenshot of the application if you think it is
+  relevant to your bug report. Here are some tips for providing a minimal
+  example: https://stackoverflow.com/help/mcve.
+-->
+
+## The current behavior
+
+
+## The expected behavior

.github/ISSUE_TEMPLATE/documentation.md

@@ -0,0 +1,13 @@
+---
+name: "📃 Documentation Issue"
+about: This issue tracker is not for documentation issues. Please file documentation issues at https://github.com/reactjs/reactjs.org.
+title: 'Docs: '
+labels: 'Resolution: Invalid'
+
+---
+
+🚨 This issue tracker is not for documentation issues. 🚨
+
+The React website is hosted on a separate repository. You may let the
+team know about any issues with the documentation by opening an issue there:
+- https://github.com/reactjs/reactjs.org/issues/new

.github/ISSUE_TEMPLATE/question.md

@@ -0,0 +1,29 @@
+---
+name: "🤔 Questions and Help"
+about: This issue tracker is not for questions. Please ask questions at https://stackoverflow.com/questions/tagged/react.
+title: 'Question: '
+labels: 'Resolution: Invalid, Type: Question'
+
+---
+
+🚨 This issue tracker is not for questions. 🚨
+
+As it happens, support requests that are created as issues are likely to be closed. We want to make sure you are able to find the help you seek. Please take a look at the following resources.
+
+## Coding Questions
+
+If you have a coding question related to React and React DOM, it might be better suited for Stack Overflow. It's a great place to browse through frequent questions about using React, as well as ask for help with specific questions.
+
+https://stackoverflow.com/questions/tagged/react
+
+## Talk to other React developers
+
+There are many online forums which are a great place for discussion about best practices and application architecture as well as the future of React.
+
+https://reactjs.org/community/support.html#popular-discussion-forums
+
+## Proposals
+
+If you'd like to discuss topics related to the future of React, or would like to propose a new feature or change before sending a pull request, please check out the discussions and proposals repository.
+
+https://github.com/reactjs/rfcs

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,14 +1,27 @@
-**Before submitting a pull request,** please make sure the following is done:
-
-1. Fork [the repository](https://github.com/facebook/react) and create your branch from `master`.
-2. Run `yarn` in the repository root.
-3. If you've fixed a bug or added code that should be tested, add tests!
-4. Ensure the test suite passes (`yarn test`). Tip: `yarn test --watch TestName` is helpful in development.
-5. Run `yarn test-prod` to test in the production environment. It supports the same options as `yarn test`.
-6. If you need a debugger, run `yarn debug-test --watch TestName`, open `chrome://inspect`, and press "Inspect".
-7. Format your code with [prettier](https://github.com/prettier/prettier) (`yarn prettier`).
-8. Make sure your code lints (`yarn lint`). Tip: `yarn linc` to only check changed files.
-9. Run the [Flow](https://flowtype.org/) typechecks (`yarn flow`).
-10. If you haven't already, complete the CLA.
-
-**Learn more about contributing:** https://reactjs.org/docs/how-to-contribute.html
+<!--
+  Thanks for submitting a pull request!
+  We appreciate you spending the time to work on these changes. Please provide enough information so that others can review your pull request. The three fields below are mandatory.
+
+  Before submitting a pull request, please make sure the following is done:
+
+  1. Fork [the repository](https://github.com/facebook/react) and create your branch from `master`.
+  2. Run `yarn` in the repository root.
+  3. If you've fixed a bug or added code that should be tested, add tests!
+  4. Ensure the test suite passes (`yarn test`). Tip: `yarn test --watch TestName` is helpful in development.
+  5. Run `yarn test-prod` to test in the production environment. It supports the same options as `yarn test`.
+  6. If you need a debugger, run `yarn debug-test --watch TestName`, open `chrome://inspect`, and press "Inspect".
+  7. Format your code with [prettier](https://github.com/prettier/prettier) (`yarn prettier`).
+  8. Make sure your code lints (`yarn lint`). Tip: `yarn linc` to only check changed files.
+  9. Run the [Flow](https://flowtype.org/) typechecks (`yarn flow`).
+  10. If you haven't already, complete the CLA.
+
+  Learn more about contributing: https://reactjs.org/docs/how-to-contribute.html
+-->
+
+## Summary
+
+<!-- Explain the **motivation** for making this change. What existing problem does the pull request solve? -->
+
+## Test Plan
+
+<!-- Demonstrate the code is solid. Example: The exact commands you ran and their output, screenshots / videos if the pull request changes the user interface. -->

CHANGELOG.md

@@ -1,11 +1,3 @@
-## [Unreleased]
-<details>
-  <summary>
-    Changes that have landed in master but are not yet released.
-    Click to see more.
-  </summary>
-</details>
-
 ## 16.12.0 (November 14, 2019)
 
 ### React DOM

SECURITY.md

@@ -0,0 +1,7 @@
+# Reporting Security Issues
+
+If you believe you have found a security vulnerability in React, we encourage you to let us know right away. We will investigate all legitimate reports and do our best to quickly fix the problem.
+
+Please refer to the following page for our responsible disclosure policy, reward guidelines, and those things that should not be reported:
+
+https://www.facebook.com/whitehat

dangerfile.js

@@ -171,7 +171,7 @@ function git(args) {
 
     for (let i = 0; i < baseArtifactsInfo.length; i++) {
       const info = baseArtifactsInfo[i];
-      if (info.path === 'home/circleci/project/build/bundle-sizes.json') {
+      if (info.path.endsWith('bundle-sizes.json')) {
         const resultsResponse = await fetch(info.url);
         previousBuildResults = await resultsResponse.json();
         break;

fixtures/dom/package.json

@@ -11,7 +11,7 @@
     "classnames": "^2.2.5",
     "codemirror": "^5.40.0",
     "core-js": "^2.4.1",
-    "jest-diff": "^24.8.0",
+    "jest-diff": "^25.1.0",
     "prop-types": "^15.6.0",
     "query-string": "^4.2.3",
     "react": "^15.4.1",

fixtures/dom/src/__tests__/nested-act-test.js

@@ -8,18 +8,23 @@
  */
 
 let React;
-let TestUtils;
+let ReactDOM;
 let TestRenderer;
 
 global.__DEV__ = process.env.NODE_ENV !== 'production';
 
+jest.mock('react-dom', () =>
+  require.requireActual('react-dom/cjs/react-dom-testing.development.js')
+);
+// we'll replace the above with react/testing and react-dom/testing right before the next minor
+
 expect.extend(require('../toWarnDev'));
 
 describe('unmocked scheduler', () => {
   beforeEach(() => {
     jest.resetModules();
     React = require('react');
-    TestUtils = require('react-dom/test-utils');
+    ReactDOM = require('react-dom');
     TestRenderer = require('react-test-renderer');
   });
 
@@ -33,7 +38,7 @@ describe('unmocked scheduler', () => {
     }
     // in legacy mode, this tests whether an act only flushes its own effects
     TestRenderer.act(() => {
-      TestUtils.act(() => {
+      ReactDOM.act(() => {
         TestRenderer.create(<Effecty />);
       });
       expect(log).toEqual([]);
@@ -42,7 +47,7 @@ describe('unmocked scheduler', () => {
 
     log = [];
     // for doublechecking, we flip it inside out, and assert on the outermost
-    TestUtils.act(() => {
+    ReactDOM.act(() => {
       TestRenderer.act(() => {
         TestRenderer.create(<Effecty />);
       });
@@ -59,7 +64,7 @@ describe('mocked scheduler', () => {
       require.requireActual('scheduler/unstable_mock')
     );
     React = require('react');
-    TestUtils = require('react-dom/test-utils');
+    ReactDOM = require('react-dom');
     TestRenderer = require('react-test-renderer');
   });
 
@@ -77,7 +82,7 @@ describe('mocked scheduler', () => {
     }
     // with a mocked scheduler, this tests whether it flushes all work only on the outermost act
     TestRenderer.act(() => {
-      TestUtils.act(() => {
+      ReactDOM.act(() => {
         TestRenderer.create(<Effecty />);
       });
       expect(log).toEqual([]);
@@ -86,7 +91,7 @@ describe('mocked scheduler', () => {
 
     log = [];
     // for doublechecking, we flip it inside out, and assert on the outermost
-    TestUtils.act(() => {
+    ReactDOM.act(() => {
       TestRenderer.act(() => {
         TestRenderer.create(<Effecty />);
       });

fixtures/dom/src/__tests__/wrong-act-test.js

@@ -12,13 +12,17 @@ let ReactDOM;
 let ReactART;
 let ARTSVGMode;
 let ARTCurrentMode;
-let TestUtils;
 let TestRenderer;
 let ARTTest;
 
 global.__DEV__ = process.env.NODE_ENV !== 'production';
 global.__EXPERIMENTAL__ = process.env.RELEASE_CHANNEL === 'experimental';
 
+jest.mock('react-dom', () =>
+  require.requireActual('react-dom/cjs/react-dom-testing.development.js')
+);
+// we'll replace the above with react/testing and react-dom/testing right before the next minor
+
 expect.extend(require('../toWarnDev'));
 
 function App(props) {
@@ -32,7 +36,6 @@ beforeEach(() => {
   ReactART = require('react-art');
   ARTSVGMode = require('art/modes/svg');
   ARTCurrentMode = require('art/modes/current');
-  TestUtils = require('react-dom/test-utils');
   TestRenderer = require('react-test-renderer');
 
   ARTCurrentMode.setCurrent(ARTSVGMode);
@@ -70,8 +73,8 @@ beforeEach(() => {
 });
 
 it("doesn't warn when you use the right act + renderer: dom", () => {
-  TestUtils.act(() => {
-    TestUtils.renderIntoDocument(<App />);
+  ReactDOM.act(() => {
+    ReactDOM.render(<App />, document.createElement('div'));
   });
 });
 
@@ -86,7 +89,7 @@ it('resets correctly across renderers', () => {
     React.useEffect(() => {}, []);
     return null;
   }
-  TestUtils.act(() => {
+  ReactDOM.act(() => {
     TestRenderer.act(() => {});
     expect(() => {
       TestRenderer.create(<Effecty />);
@@ -99,7 +102,7 @@ it('resets correctly across renderers', () => {
 it('warns when using the wrong act version - test + dom: render', () => {
   expect(() => {
     TestRenderer.act(() => {
-      TestUtils.renderIntoDocument(<App />);
+      ReactDOM.render(<App />, document.createElement('div'));
     });
   }).toWarnDev(["It looks like you're using the wrong act()"], {
     withoutStack: true,
@@ -113,7 +116,7 @@ it('warns when using the wrong act version - test + dom: updates', () => {
     setCtr = _setCtr;
     return ctr;
   }
-  TestUtils.renderIntoDocument(<Counter />);
+  ReactDOM.render(<Counter />, document.createElement('div'));
   expect(() => {
     TestRenderer.act(() => {
       setCtr(1);
@@ -123,7 +126,7 @@ it('warns when using the wrong act version - test + dom: updates', () => {
 
 it('warns when using the wrong act version - dom + test: .create()', () => {
   expect(() => {
-    TestUtils.act(() => {
+    ReactDOM.act(() => {
       TestRenderer.create(<App />);
     });
   }).toWarnDev(["It looks like you're using the wrong act()"], {
@@ -134,7 +137,7 @@ it('warns when using the wrong act version - dom + test: .create()', () => {
 it('warns when using the wrong act version - dom + test: .update()', () => {
   const root = TestRenderer.create(<App key="one" />);
   expect(() => {
-    TestUtils.act(() => {
+    ReactDOM.act(() => {
       root.update(<App key="two" />);
     });
   }).toWarnDev(["It looks like you're using the wrong act()"], {
@@ -151,15 +154,15 @@ it('warns when using the wrong act version - dom + test: updates', () => {
   }
   TestRenderer.create(<Counter />);
   expect(() => {
-    TestUtils.act(() => {
+    ReactDOM.act(() => {
       setCtr(1);
     });
   }).toWarnDev(["It looks like you're using the wrong act()"]);
 });
 
 it('does not warn when nesting react-act inside react-dom', () => {
-  TestUtils.act(() => {
-    TestUtils.renderIntoDocument(<ARTTest />);
+  ReactDOM.act(() => {
+    ReactDOM.render(<ARTTest />, document.createElement('div'));
   });
 });
 
@@ -171,7 +174,7 @@ it('does not warn when nesting react-act inside react-test-renderer', () => {
 
 it("doesn't warn if you use nested acts from different renderers", () => {
   TestRenderer.act(() => {
-    TestUtils.act(() => {
+    ReactDOM.act(() => {
       TestRenderer.create(<App />);
     });
   });

fixtures/dom/src/components/Header.js

@@ -86,6 +86,7 @@ class Header extends React.Component {
                 <option value="/mouse-events">Mouse Events</option>
                 <option value="/selection-events">Selection Events</option>
                 <option value="/suspense">Suspense</option>
+                <option value="/form-state">Form State</option>
               </select>
             </label>
             <label htmlFor="global_version">