From 2757a53fa5546236bdfa498724a270cf8db76e89 Mon Sep 17 00:00:00 2001
From: Jason Quense <monastic.panic@gmail.com>
Date: Thu, 2 Mar 2017 14:38:27 -0500
Subject: [PATCH] Add fixture components (#8860)

* add fixture components

* add a few more options and styles

* Test fixture updates

- Pull in React from window global
- Add field to TestCase for fix PR links
- Update some styles

* Remove unused Fixture.Result comment

* Remove leading # from resolvedBy link

* Implement tag loading utility that caches response

Don't bust the cache doing feature detection

COME ON

* Use 'local' without version for option
---
 fixtures/dom/package.json                     |   4 +-
 fixtures/dom/src/components/Fixture.js        |  21 +++
 fixtures/dom/src/components/FixtureSet.js     |  28 ++++
 fixtures/dom/src/components/Header.js         |   9 +-
 fixtures/dom/src/components/TestCase.js       | 145 ++++++++++++++++++
 fixtures/dom/src/components/fixtures/index.js |   5 +-
 .../InputPlaceholderFixture.js                |  61 ++++++++
 .../input-change-events/RadioClickFixture.js  |  52 +++++++
 .../RangeKeyboardFixture.js                   |  75 +++++++++
 .../fixtures/input-change-events/index.js     |  81 ++++++++++
 .../components/fixtures/text-inputs/index.js  |   4 +-
 fixtures/dom/src/components/propTypes.js      |  16 ++
 fixtures/dom/src/style.css                    | 144 +++++++++++++++--
 fixtures/dom/src/tags.js                      |  70 +++++++++
 fixtures/dom/yarn.lock                        |   4 +
 15 files changed, 701 insertions(+), 18 deletions(-)
 create mode 100644 fixtures/dom/src/components/Fixture.js
 create mode 100644 fixtures/dom/src/components/FixtureSet.js
 create mode 100644 fixtures/dom/src/components/TestCase.js
 create mode 100644 fixtures/dom/src/components/fixtures/input-change-events/InputPlaceholderFixture.js
 create mode 100644 fixtures/dom/src/components/fixtures/input-change-events/RadioClickFixture.js
 create mode 100644 fixtures/dom/src/components/fixtures/input-change-events/RangeKeyboardFixture.js
 create mode 100644 fixtures/dom/src/components/fixtures/input-change-events/index.js
 create mode 100644 fixtures/dom/src/components/propTypes.js
 create mode 100644 fixtures/dom/src/tags.js

diff --git a/fixtures/dom/package.json b/fixtures/dom/package.json
index cc109e10018fb..5de1a7d4b8d17 100644
--- a/fixtures/dom/package.json
+++ b/fixtures/dom/package.json
@@ -6,9 +6,11 @@
     "react-scripts": "0.8.4"
   },
   "dependencies": {
+    "classnames": "^2.2.5",
     "query-string": "^4.2.3",
     "react": "^15.4.1",
-    "react-dom": "^15.4.1"
+    "react-dom": "^15.4.1",
+    "semver": "^5.3.0"
   },
   "scripts": {
     "start": "react-scripts start",
diff --git a/fixtures/dom/src/components/Fixture.js b/fixtures/dom/src/components/Fixture.js
new file mode 100644
index 0000000000000..1f6ef9ba09997
--- /dev/null
+++ b/fixtures/dom/src/components/Fixture.js
@@ -0,0 +1,21 @@
+const React = window.React;
+
+const propTypes = {
+  children: React.PropTypes.node.isRequired,
+};
+
+class Fixture extends React.Component {
+  render() {
+    const { children } = this.props;
+
+    return (
+      <div className="test-fixture">
+        {children}
+      </div>
+    );
+  }
+}
+
+Fixture.propTypes = propTypes;
+
+export default Fixture
diff --git a/fixtures/dom/src/components/FixtureSet.js b/fixtures/dom/src/components/FixtureSet.js
new file mode 100644
index 0000000000000..9c6e8581eba4b
--- /dev/null
+++ b/fixtures/dom/src/components/FixtureSet.js
@@ -0,0 +1,28 @@
+import React from 'react';
+
+const propTypes = {
+  title: React.PropTypes.node.isRequired,
+  description: React.PropTypes.node.isRequired,
+};
+
+class FixtureSet extends React.Component {
+
+  render() {
+    const { title, description, children } = this.props;
+
+    return (
+      <div>
+        <h1>{title}</h1>
+        {description  && (
+          <p>{description}</p>
+        )}
+
+        {children}
+      </div>
+    );
+  }
+}
+
+FixtureSet.propTypes = propTypes;
+
+export default FixtureSet
diff --git a/fixtures/dom/src/components/Header.js b/fixtures/dom/src/components/Header.js
index fb9d143f0ff43..83f77eee31c20 100644
--- a/fixtures/dom/src/components/Header.js
+++ b/fixtures/dom/src/components/Header.js
@@ -1,4 +1,5 @@
 import { parse, stringify } from 'query-string';
+import getVersionTags from '../tags';
 const React = window.React;
 
 const Header = React.createClass({
@@ -9,13 +10,12 @@ const Header = React.createClass({
     return { version, versions };
   },
   componentWillMount() {
-    fetch('https://api.github.com/repos/facebook/react/tags', { mode: 'cors' })
-      .then(res => res.json())
+    getVersionTags()
       .then(tags => {
         let versions = tags.map(tag => tag.name.slice(1));
-        versions = ['local', ...versions];
+        versions = [`local`, ...versions];
         this.setState({ versions });
-      });
+      })
   },
   handleVersionChange(event) {
     const query = parse(window.location.search);
@@ -46,6 +46,7 @@ const Header = React.createClass({
               <option value="/text-inputs">Text Inputs</option>
               <option value="/selects">Selects</option>
               <option value="/textareas">Textareas</option>
+              <option value="/input-change-events">Input change events</option>
             </select>
           </label>
           <label htmlFor="react_version">
diff --git a/fixtures/dom/src/components/TestCase.js b/fixtures/dom/src/components/TestCase.js
new file mode 100644
index 0000000000000..79c46a975afbc
--- /dev/null
+++ b/fixtures/dom/src/components/TestCase.js
@@ -0,0 +1,145 @@
+import cn from 'classnames';
+import semver from 'semver';
+import React from 'react';
+import { parse } from 'query-string';
+import { semverString } from './propTypes'
+
+const propTypes = {
+  children: React.PropTypes.node.isRequired,
+  title: React.PropTypes.node.isRequired,
+  resolvedIn: semverString,
+  resolvedBy: React.PropTypes.string
+};
+
+class TestCase extends React.Component {
+  constructor(props, context) {
+    super(props, context);
+
+    this.state = {
+      complete: false,
+    };
+  }
+
+  handleChange = (e) => {
+    this.setState({
+      complete: e.target.checked
+    })
+  };
+
+  render() {
+    const {
+      title,
+      description,
+      resolvedIn,
+      resolvedBy,
+      affectedBrowsers,
+      children,
+    } = this.props;
+
+    let { complete } = this.state;
+
+    const { version } = parse(window.location.search);
+    const isTestRelevant = (
+      !version ||
+      !resolvedIn ||
+      semver.gte(version, resolvedIn)
+    );
+
+    complete = !isTestRelevant || complete;
+
+    return (
+      <section
+        className={cn(
+          "test-case",
+          complete && 'test-case--complete'
+        )}
+      >
+        <h2 className="test-case__title type-subheading">
+          <label>
+            <input
+              className="test-case__title__check"
+              type="checkbox"
+              checked={complete}
+              onChange={this.handleChange}
+            />
+            {' '}{title}
+          </label>
+        </h2>
+
+        <dl className="test-case__details">
+          {resolvedIn && (
+            <dt>First supported in: </dt>)}
+          {resolvedIn && (
+             <dd>
+               <a href={'https://github.com/facebook/react/tag/v' + resolvedIn}>
+                 <code>{resolvedIn}</code>
+               </a>
+             </dd>
+           )}
+
+          {resolvedBy && (
+            <dt>Fixed by: </dt>)}
+          {resolvedBy && (
+            <dd>
+              <a href={'https://github.com/facebook/react/pull/' + resolvedBy.slice(1)}>
+                <code>{resolvedBy}</code>
+              </a>
+            </dd>
+          )}
+
+          {affectedBrowsers &&
+            <dt>Affected browsers: </dt>}
+          {affectedBrowsers &&
+            <dd>{affectedBrowsers}</dd>
+          }
+        </dl>
+
+        <p className="test-case__desc">
+          {description}
+        </p>
+
+        <div className="test-case__body">
+          {!isTestRelevant &&(
+             <p className="test-case__invalid-version">
+               <strong>Note:</strong> This test case was fixed in a later version of React.
+               This test is not expected to pass for the selected version, and that's ok!
+             </p>
+           )}
+
+          {children}
+        </div>
+      </section>
+    );
+  }
+}
+
+TestCase.propTypes = propTypes;
+
+TestCase.Steps = class extends React.Component {
+  render() {
+    const { children } = this.props;
+    return (
+      <div>
+        <h3>Steps to reproduce:</h3>
+        <ol>
+          {children}
+        </ol>
+      </div>
+    )
+  }
+}
+
+TestCase.ExpectedResult = class extends React.Component {
+  render() {
+    const { children } = this.props
+    return (
+      <div>
+        <h3>Expected Result:</h3>
+        <p>
+          {children}
+        </p>
+      </div>
+    )
+  }
+}
+export default TestCase
diff --git a/fixtures/dom/src/components/fixtures/index.js b/fixtures/dom/src/components/fixtures/index.js
index b0e70baf994ea..ea7cebbde8899 100644
--- a/fixtures/dom/src/components/fixtures/index.js
+++ b/fixtures/dom/src/components/fixtures/index.js
@@ -2,7 +2,8 @@ const React = window.React;
 import RangeInputFixtures from './range-inputs';
 import TextInputFixtures from './text-inputs';
 import SelectFixtures from './selects';
-import TextAreaFixtures from './textareas/';
+import TextAreaFixtures from './textareas';
+import InputChangeEvents from './input-change-events';
 
 /**
  * A simple routing component that renders the appropriate
@@ -19,6 +20,8 @@ const FixturesPage = React.createClass({
         return <SelectFixtures />;
       case '/textareas':
         return <TextAreaFixtures />;
+      case '/input-change-events':
+        return <InputChangeEvents />;
       default:
         return <p>Please select a test fixture.</p>;
     }
diff --git a/fixtures/dom/src/components/fixtures/input-change-events/InputPlaceholderFixture.js b/fixtures/dom/src/components/fixtures/input-change-events/InputPlaceholderFixture.js
new file mode 100644
index 0000000000000..35419b896a71a
--- /dev/null
+++ b/fixtures/dom/src/components/fixtures/input-change-events/InputPlaceholderFixture.js
@@ -0,0 +1,61 @@
+import React from 'react';
+
+import Fixture from '../../Fixture';
+
+
+
+class InputPlaceholderFixture extends React.Component {
+  constructor(props, context) {
+    super(props, context);
+
+    this.state = {
+      placeholder: 'A placeholder',
+      changeCount: 0,
+    };
+  }
+
+  handleChange = () => {
+    this.setState(({ changeCount }) => {
+      return {
+        changeCount: changeCount + 1
+      }
+    })
+  }
+  handleGeneratePlaceholder = () => {
+    this.setState({
+      placeholder: `A placeholder: ${Math.random() * 100}`
+    })
+  }
+
+  handleReset = () => {
+    this.setState({
+      changeCount: 0,
+    })
+  }
+
+  render() {
+    const { placeholder, changeCount } = this.state;
+    const color = changeCount === 0 ? 'green' : 'red';
+
+    return (
+      <Fixture>
+        <input
+          type='text'
+          placeholder={placeholder}
+          onChange={this.handleChange}
+        />
+        {' '}
+        <button onClick={this.handleGeneratePlaceholder}>
+          Change placeholder
+        </button>
+
+        <p style={{ color }}>
+          <code>onChange</code>{' calls: '}<strong>{changeCount}</strong>
+        </p>
+        <button onClick={this.handleReset}>Reset count</button>
+      </Fixture>
+    )
+  }
+}
+
+export default InputPlaceholderFixture;
diff --git a/fixtures/dom/src/components/fixtures/input-change-events/RadioClickFixture.js b/fixtures/dom/src/components/fixtures/input-change-events/RadioClickFixture.js
new file mode 100644
index 0000000000000..fb44166b34b0b
--- /dev/null
+++ b/fixtures/dom/src/components/fixtures/input-change-events/RadioClickFixture.js
@@ -0,0 +1,52 @@
+import React from 'react';
+
+import Fixture from '../../Fixture';
+
+class RadioClickFixture extends React.Component {
+  constructor(props, context) {
+    super(props, context);
+
+    this.state = {
+      changeCount: 0,
+    };
+  }
+
+  handleChange = () => {
+    this.setState(({ changeCount }) => {
+      return {
+        changeCount: changeCount + 1
+      }
+    })
+  }
+
+  handleReset = () => {
+    this.setState({
+      changeCount: 0,
+    })
+  }
+
+  render() {
+    const { changeCount } = this.state;
+    const color = changeCount === 0 ? 'green' : 'red';
+    
+    return (
+      <Fixture>
+        <label>
+          <input
+            defaultChecked
+            type='radio'
+            onChange={this.handleChange}
+          />
+          Test case radio input
+        </label>
+        {' '}
+        <p style={{ color }}>
+          <code>onChange</code>{' calls: '}<strong>{changeCount}</strong>
+        </p>
+        <button onClick={this.handleReset}>Reset count</button>
+      </Fixture>
+    )
+  }
+}
+
+export default RadioClickFixture;
diff --git a/fixtures/dom/src/components/fixtures/input-change-events/RangeKeyboardFixture.js b/fixtures/dom/src/components/fixtures/input-change-events/RangeKeyboardFixture.js
new file mode 100644
index 0000000000000..12ccd1f43ac47
--- /dev/null
+++ b/fixtures/dom/src/components/fixtures/input-change-events/RangeKeyboardFixture.js
@@ -0,0 +1,75 @@
+import React from 'react';
+
+import Fixture from '../../Fixture';
+
+
+class RangeKeyboardFixture extends React.Component {
+  constructor(props, context) {
+    super(props, context);
+
+    this.state = {
+      keydownCount: 0,
+      changeCount: 0,
+    };
+  }
+
+  componentDidMount() {
+    this.input.addEventListener('keydown', this.handleKeydown, false)
+  }
+
+  componentWillUnmount() {
+    this.input.removeEventListener('keydown', this.handleKeydown, false)
+  }
+
+  handleChange = () => {
+    this.setState(({ changeCount }) => {
+      return {
+        changeCount: changeCount + 1
+      }
+    })
+  }
+
+  handleKeydown = (e) => {
+    // only interesting in arrow key events
+    if (![37, 38, 39, 40].includes(e.keyCode))
+      return;
+
+    this.setState(({ keydownCount }) => {
+      return {
+        keydownCount: keydownCount + 1
+      }
+    })
+  }
+
+  handleReset = () => {
+    this.setState({
+      keydownCount: 0,
+      changeCount: 0,
+    })
+  }
+
+  render() {
+    const { keydownCount, changeCount } = this.state;
+    const color = keydownCount === changeCount ? 'green' : 'red';
+
+    return (
+      <Fixture>
+        <input
+          type='range'
+          ref={r => this.input = r}
+          onChange={this.handleChange}
+        />
+        {' '}
+
+        <p style={{ color }}>
+          <code>onKeyDown</code>{' calls: '}<strong>{keydownCount}</strong>
+          {' vs '}
+          <code>onChange</code>{' calls: '}<strong>{changeCount}</strong>
+        </p>
+        <button onClick={this.handleReset}>Reset counts</button>
+      </Fixture>
+    )
+  }
+}
+
+export default RangeKeyboardFixture;
diff --git a/fixtures/dom/src/components/fixtures/input-change-events/index.js b/fixtures/dom/src/components/fixtures/input-change-events/index.js
new file mode 100644
index 0000000000000..703585ed43795
--- /dev/null
+++ b/fixtures/dom/src/components/fixtures/input-change-events/index.js
@@ -0,0 +1,81 @@
+import React from 'react';
+
+import FixtureSet from '../../FixtureSet';
+import TestCase from '../../TestCase';
+import RangeKeyboardFixture from './RangeKeyboardFixture';
+import RadioClickFixture from './RadioClickFixture';
+import InputPlaceholderFixture from './InputPlaceholderFixture';
+
+class InputChangeEvents extends React.Component {
+  render() {
+    return (
+      <FixtureSet
+        title="Input change events"
+        description="Tests proper behavior of the onChange event for inputs"
+      >
+        <TestCase
+          title="Range keyboard changes"
+          description={`
+            Range inputs should fire onChange events for keyboard events
+          `}
+        >
+          <TestCase.Steps>
+            <li>Focus range input</li>
+            <li>change value via the keyboard arrow keys</li>
+          </TestCase.Steps>
+
+          <TestCase.ExpectedResult>
+            The <code>onKeyDown</code> call count should be equal to
+            the <code>onChange</code> call count.
+          </TestCase.ExpectedResult>
+
+          <RangeKeyboardFixture />
+        </TestCase>
+
+        <TestCase
+          title="Radio input clicks"
+          description={`
+            Radio inputs should only fire change events when the checked
+            state changes.
+          `}
+          resolvedIn="16.0.0"
+        >
+          <TestCase.Steps>
+            <li>Click on the Radio input (or label text)</li>
+          </TestCase.Steps>
+
+          <TestCase.ExpectedResult>
+            The <code>onChange</code> call count should remain at 0
+          </TestCase.ExpectedResult>
+
+          <RadioClickFixture />
+        </TestCase>
+
+        <TestCase
+          title="Inputs with placeholders"
+          description={`
+            Text inputs with placeholders should not trigger changes
+            when the placeholder is altered
+          `}
+          resolvedIn="15.0.0"
+          resolvedBy="#5004"
+          affectedBrowsers="IE9+"
+        >
+          <TestCase.Steps>
+            <li>Click on the Text input</li>
+            <li>Click on the "Change placeholder" button</li>
+          </TestCase.Steps>
+
+          <TestCase.ExpectedResult>
+            The <code>onChange</code> call count should remain at 0
+          </TestCase.ExpectedResult>
+
+          <InputPlaceholderFixture />
+        </TestCase>
+      </FixtureSet>
+    );
+  }
+}
+
+
+export default InputChangeEvents
diff --git a/fixtures/dom/src/components/fixtures/text-inputs/index.js b/fixtures/dom/src/components/fixtures/text-inputs/index.js
index ece6397bc3f92..2db132bcb1032 100644
--- a/fixtures/dom/src/components/fixtures/text-inputs/index.js
+++ b/fixtures/dom/src/components/fixtures/text-inputs/index.js
@@ -24,7 +24,7 @@ const TextInputFixtures = React.createClass({
 
     return (
       <div key={type} className="field">
-        <label htmlFor={id}>{type}</label>
+        <label className="control-label" htmlFor={id}>{type}</label>
         <input id={id} type={type} value={state} onChange={onChange} />
         &nbsp; &rarr; {JSON.stringify(state)}
       </div>
@@ -35,7 +35,7 @@ const TextInputFixtures = React.createClass({
     let id = `uncontrolled_${type}`;
     return (
       <div key={type} className="field">
-        <label htmlFor={id}>{type}</label>
+        <label className="control-label" htmlFor={id}>{type}</label>
         <input id={id} type={type} />
       </div>
     );
diff --git a/fixtures/dom/src/components/propTypes.js b/fixtures/dom/src/components/propTypes.js
new file mode 100644
index 0000000000000..42f4f4cf3ae27
--- /dev/null
+++ b/fixtures/dom/src/components/propTypes.js
@@ -0,0 +1,16 @@
+import semver from 'semver';
+
+const React = window.React;
+
+export function semverString (props, propName, componentName) {
+  let version = props[propName];
+
+  let error = React.PropTypes.string(...arguments);
+  if (!error && version != null && !semver.valid(version))
+    error = new Error(
+      `\`${propName}\` should be a valid "semantic version" matching ` +
+      'an existing React version'
+    );
+
+  return error || null;
+};
diff --git a/fixtures/dom/src/style.css b/fixtures/dom/src/style.css
index 6a7101c1f9b49..032d0c85f68b7 100644
--- a/fixtures/dom/src/style.css
+++ b/fixtures/dom/src/style.css
@@ -4,22 +4,28 @@
   box-sizing: border-box;
 }
 
+html {
+  font-size: 10px;
+}
 body {
   font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", "Oxygen", "Ubuntu", "Cantarell", "Fira Sans", "Droid Sans", "Helvetica Neue", sans-serif;
+  font-size: 1.4rem;
   margin: 0;
   padding: 0;
 }
 
 select {
-  width: 120px;
+  width: 12rem;
 }
 
+
 .header {
   background: #222;
   box-shadow: inset 0 -1px 3px #000;
-  line-height: 32px;
+  font-size: 1.6rem;
+  line-height: 3.2rem;
   overflow: hidden;
-  padding: 8px 16px;
+  padding: .8rem 1.6rem;
 }
 
 .header__inner {
@@ -40,7 +46,7 @@ select {
 
 .header__logo img {
   display: inline-block;
-  margin-right: 8px;
+  margin-right: 0.8rem;
   vertical-align: middle;
 }
 
@@ -63,24 +69,142 @@ select {
   margin: 0 auto;
   max-width: 900px;
   overflow: hidden;
-  padding: 20px;
+  padding: 2rem;
 }
 
-label {
+.control-label {
   display: block;
-  font-size: 12px;
+  font-size: 1.2rem;
   letter-spacing: 0.01em;
-  margin-bottom: 4px;
+  margin-bottom: 0.4rem;
   text-transform: uppercase;
 }
 
 .field {
-  padding: 8px;
+  padding: 0.8rem;
 }
 
 fieldset {
   border: 1px solid #aaa;
   float: left;
-  padding: 16px;
+  padding: 1.6rem;
   width: 49%;
 }
+
+.control-box {
+  overflow: hidden;
+}
+
+ul, ol {
+  margin: 0 0 2rem 0;
+}
+
+li {
+  margin-bottom: 0.4rem;
+}
+
+.type-subheading {
+  font-size: 1.8rem;
+  font-weight: 600;
+  line-height: 1.5;
+  margin: 0 0 1.6rem;
+}
+
+.hint {
+  font-style: italic;
+  line-height: 1.5;
+  text-size: 1.4rem;
+}
+
+.footnote {
+  border-left: 4px solid #aaa;
+  color: #444;
+  font-style: italic;
+  line-height: 1.5;
+  margin-bottom: 2.4rem;
+  margin-left: 0.4rem;
+  padding-left: 1.6rem;
+  text-size: 1.3rem;
+}
+
+.test-case {
+  border-radius: 0.2rem;
+  border: 1px solid #d9d9d9;
+  margin: 3.2rem 0 3.2rem;
+}
+
+.test-case__title {
+  padding: 10px 15px 8px;
+  line-height: 16px;
+  font-size: 18px;
+  border-bottom: 1px dashed #d9d9d9;
+  margin: 0 0 -1px;
+}
+
+.test-case__title__check {
+  display: inline-block;
+  margin-right: 8px;
+  vertical-align: middle;
+}
+
+.test-case__body {
+  padding: 0 15px;
+}
+
+.test-case__desc {
+  font-style: italic;
+  margin: 15px 0;
+  padding: 0 15px;
+}
+
+.test-case--complete {
+  border-color: #5cb85c;
+}
+
+.test-case--complete .test-case__title {
+  color: #5cb85c;
+}
+
+.test-case__details {
+  border-bottom: 1px dashed #d9d9d9;
+  font-size: 80%;
+  text-transform: uppercase;
+  letter-spacing: 0.02em;
+  margin: 0;
+  padding: 0 15px;
+}
+
+.test-case__details > * {
+  display: inline-block;
+}
+
+.test-case__details > dt,
+.test-case__details > dd {
+  padding: 8px 0 6px;
+}
+
+.test-case__details > dt {
+  color: #464a4c;
+  font-weight: 600;
+}
+
+.test-case__details > dd {
+  margin-left: 1rem;
+}
+
+.test-case__details > dd + dt {
+  margin-left: 1.5rem;
+}
+
+.test-case__invalid-version {
+  font-style: italic;
+  font-size: 1.6rem;
+  color: #5cb85c;
+}
+
+.test-fixture {
+  padding: 20px;
+  margin: 0 -15px; /* opposite of .test-case padding */
+  background-color: #f4f4f4;
+  border-top: 1px solid #d9d9d9;
+}
diff --git a/fixtures/dom/src/tags.js b/fixtures/dom/src/tags.js
new file mode 100644
index 0000000000000..a82c3e5d299f1
--- /dev/null
+++ b/fixtures/dom/src/tags.js
@@ -0,0 +1,70 @@
+/**
+ * Version tags are loaded from the Github API. Since the Github API is rate-limited
+ * we attempt to save and load the tags in sessionStorage when possible. Since its unlikely
+ * that versions will change during a single session this should be safe.
+ */
+
+const TAGS_CACHE_KEY = '@react-dom-fixtures/tags';
+
+/**
+ * Its possible that users will be testing changes frequently
+ * in a browser that does not support sessionStorage. If the API does
+ * get rate limited this hardcoded fallback will be loaded instead.
+ * This way users can still switch between ~some versions while testing.
+ * If there's a specific version they need to test that is not here, they
+ * can manually load it by editing the URL (`?version={whatever}`)
+ */
+const fallbackTags = [
+  '15.4.2',
+  '15.3.2',
+  '15.2.1',
+  '15.1.0',
+  '15.0.2',
+  '0.14.8',
+  '0.13.0'
+  ].map(version => ({
+    name: `v${version}`
+  }))
+
+let canUseSessionStorage = true;
+
+try {
+  sessionStorage.setItem('foo', '')
+} catch (err) {
+  canUseSessionStorage = false;
+}
+
+/**
+ * Attempts to load tags from sessionStorage. In cases where
+ * sessionStorage is not available (Safari private browsing) or the
+ * tags are cached a fetch request is made to the Github API.
+ * 
+ * Returns a promise so that the consuming module can always assume
+ * the request is async, even if its loaded from sessionStorage.
+ */
+export default function getVersionTags() {
+  return new Promise((resolve) => {
+    let cachedTags;
+    if (canUseSessionStorage) {
+      cachedTags = sessionStorage.getItem(TAGS_CACHE_KEY);
+    }
+    if (cachedTags) {
+      cachedTags = JSON.parse(cachedTags);
+      resolve(cachedTags);
+    } else {
+      fetch('https://api.github.com/repos/facebook/react/tags', { mode: 'cors' })
+        .then(res => res.json())
+        .then(tags => {
+          // A message property indicates an error was sent from the API
+          if (tags.message) {
+            return resolve(fallbackTags)
+          }
+          if (canUseSessionStorage) {
+            sessionStorage.setItem(TAGS_CACHE_KEY, JSON.stringify(tags))
+          }
+          resolve(tags)
+        })
+        .catch(() => resolve(fallbackTags))
+    }
+  })
+}
\ No newline at end of file
diff --git a/fixtures/dom/yarn.lock b/fixtures/dom/yarn.lock
index c8780701e0c06..6136f0a9cffbe 100644
--- a/fixtures/dom/yarn.lock
+++ b/fixtures/dom/yarn.lock
@@ -1136,6 +1136,10 @@ clap@^1.0.9:
   dependencies:
     chalk "^1.1.3"
 
+classnames@^2.2.5:
+  version "2.2.5"
+  resolved "https://registry.yarnpkg.com/classnames/-/classnames-2.2.5.tgz#fb3801d453467649ef3603c7d61a02bd129bde6d"
+
 clean-css@3.4.x:
   version "3.4.23"
   resolved "https://registry.yarnpkg.com/clean-css/-/clean-css-3.4.23.tgz#604fbbca24c12feb59b02f00b84f1fb7ded6d001"