Add tests for React 16 to CI

eslint.config.ts

@@ -184,6 +184,12 @@ const config = tsEslint.config([
       '@typescript-eslint/restrict-template-expressions': 'off',
     },
   },
+  {
+    files: ['**/app-react16/**/*'],
+    rules: {
+      'react/no-deprecated': 'off',
+    },
+  },
   // must be the last config in the array
   // https://github.com/prettier/eslint-plugin-prettier?tab=readme-ov-file#configuration-new-eslintconfigjs
   prettierRecommended,

knip.ts

@@ -54,6 +54,7 @@ const config: KnipConfig = {
         // Declaring this as webpack.config instead doesn't work correctly
         'config/webpack/webpack.config.js',
       ],
+      ignore: ['**/app-react16/**/*'],
       project: ['**/*.{js,cjs,mjs,jsx,ts,cts,mts,tsx}!', 'config/webpack/*.js'],
       paths: {
         'Assets/*': ['client/app/assets/*'],

script/convert

@@ -8,26 +8,47 @@ def gsub_file_content(path, old_content, new_content)
   File.binwrite(path, content)
 end
 
-old_config = File.expand_path("../spec/dummy/config/shakapacker.yml", __dir__)
-new_config = File.expand_path("../spec/dummy/config/webpacker.yml", __dir__)
+def move(old_path, new_path)
+  old_path = File.expand_path(old_path, __dir__)
+  new_path = File.expand_path(new_path, __dir__)
+  File.rename(old_path, new_path)
+end
 
-File.rename(old_config, new_config)
+move("../spec/dummy/config/shakapacker.yml", "../spec/dummy/config/webpacker.yml")
 
+# Shakapacker
 gsub_file_content("../Gemfile.development_dependencies", /gem "shakapacker", "[^"]*"/, 'gem "shakapacker", "6.6.0"')
+gsub_file_content("../spec/dummy/package.json", /"shakapacker": "[^"]*",/, '"shakapacker": "6.6.0",')
 
 # The below packages don't work on the oldest supported Node version and aren't needed there anyway
 gsub_file_content("../package.json", /"eslint": "[^"]*",/, "")
 gsub_file_content("../package.json", /"globals": "[^"]*",/, "")
 gsub_file_content("../package.json", /"knip": "[^"]*",/, "")
+gsub_file_content("../package.json", /"publint": "[^"]*",/, "")
 gsub_file_content("../package.json", /"typescript-eslint": "[^"]*",/, "")
 gsub_file_content("../package.json", %r{"@arethetypeswrong/cli": "[^"]*",}, "")
 gsub_file_content("../package.json", %r{"@eslint/compat": "[^"]*",}, "")
 gsub_file_content("../package.json", %r{"@testing-library/dom": "[^"]*",}, "")
 gsub_file_content("../package.json", %r{"@testing-library/react": "[^"]*",}, "")
-gsub_file_content("../package.json", /"knip": "[^"]*",/, "")
-gsub_file_content("../package.json", /"publint": "[^"]*",/, "")
 
-gsub_file_content("../spec/dummy/package.json", /"shakapacker": "[^"]*",/, '"shakapacker": "6.6.0",')
+# Switch to the oldest supported React version
+gsub_file_content("../package.json", /"react": "[^"]*",/, '"react": "16.14.0",')
+gsub_file_content("../package.json", /"react-dom": "[^"]*",/, '"react-dom": "16.14.0",')
+gsub_file_content("../spec/dummy/package.json", /"react": "[^"]*",/, '"react": "16.14.0",')
+gsub_file_content("../spec/dummy/package.json", /"react-dom": "[^"]*",/, '"react-dom": "16.14.0",')
+gsub_file_content(
+  "../package.json",
+  "jest node_package/tests",
+  'jest node_package/tests --testPathIgnorePatterns=\".*(RSC|stream|serverRenderReactComponent).*\"'
+)
+gsub_file_content("../tsconfig.json", "react-jsx", "react")
+gsub_file_content("../spec/dummy/babel.config.js", "runtime: 'automatic'", "runtime: 'classic'")
+# https://rescript-lang.org/docs/react/latest/migrate-react#configuration
+gsub_file_content("../spec/dummy/rescript.json", '"version": 4', '"version": 4, "mode": "classic"')
+# Find all files under app-react16 and replace the React 19 versions
+Dir.glob(File.expand_path("../spec/dummy/**/app-react16/**/*.*", __dir__)).each do |file|
+  move(file, file.gsub("-react16", ""))
+end
 
 gsub_file_content("../spec/dummy/config/webpack/commonWebpackConfig.js", /generateWebpackConfig(\(\))?/,
                   "webpackConfig")

spec/dummy/client/app-react16/startup/ManualRenderApp.jsx

@@ -0,0 +1,18 @@
+import React from 'react';
+import ReactDOM from 'react-dom';
+
+export default (props, _railsContext, domNodeId) => {
+  const reactElement = (
+    <div>
+      <h1 id="manual-render">Manual Render Example</h1>
+      <p>If you can see this, you can register renderer functions.</p>
+    </div>
+  );
+
+  const domNode = document.getElementById(domNodeId);
+  if (props.prerender) {
+    ReactDOM.hydrate(reactElement, domNode);
+  } else {
+    ReactDOM.render(reactElement, domNode);
+  }
+};

spec/dummy/client/app-react16/startup/ReduxApp.client.jsx

@@ -0,0 +1,57 @@
+// Top level component for client side.
+// Compare this to the ./ServerApp.jsx file which is used for server side rendering.
+// NOTE: these are basically the same, but they are shown here
+
+import React from 'react';
+import { combineReducers, applyMiddleware, createStore } from 'redux';
+import { Provider } from 'react-redux';
+import thunkMiddleware from 'redux-thunk';
+import ReactDOM from 'react-dom';
+
+import reducers from '../../app/reducers/reducersIndex';
+import composeInitialState from '../../app/store/composeInitialState';
+
+import HelloWorldContainer from '../../app/components/HelloWorldContainer';
+
+/*
+ *  Export a function that takes the props and returns a ReactComponent.
+ *  This is used for the client rendering hook after the page html is rendered.
+ *  React will see that the state is the same and not do anything.
+ *
+ */
+export default (props, railsContext, domNodeId) => {
+  const render = props.prerender ? ReactDOM.hydrate : ReactDOM.render;
+  // eslint-disable-next-line no-param-reassign
+  delete props.prerender;
+
+  const combinedReducer = combineReducers(reducers);
+  const combinedProps = composeInitialState(props, railsContext);
+
+  // This is where we'll put in the middleware for the async function. Placeholder.
+  // store will have helloWorldData as a top level property
+  const store = createStore(combinedReducer, combinedProps, applyMiddleware(thunkMiddleware));
+
+  // renderApp is a function required for hot reloading. see
+  // https://github.com/retroalgic/react-on-rails-hot-minimal/blob/master/client/src/entry.js
+
+  // Provider uses this.props.children, so we're not typical React syntax.
+  // This allows redux to add additional props to the HelloWorldContainer.
+  const renderApp = (Komponent) => {
+    const element = (
+      <Provider store={store}>
+        <Komponent />
+      </Provider>
+    );
+
+    render(element, document.getElementById(domNodeId));
+  };
+
+  renderApp(HelloWorldContainer);
+
+  if (module.hot) {
+    module.hot.accept(['../reducers/reducersIndex', '../components/HelloWorldContainer'], () => {
+      store.replaceReducer(combineReducers(reducers));
+      renderApp(HelloWorldContainer);
+    });
+  }
+};

spec/dummy/client/app-react16/startup/ReduxSharedStoreApp.client.jsx

@@ -0,0 +1,45 @@
+// Top level component for the client side.
+// Compare this to the ./ReduxSharedStoreApp.server.jsx file which is used for server side rendering.
+
+import React from 'react';
+import { Provider } from 'react-redux';
+import ReactOnRails from 'react-on-rails/client';
+import ReactDOM from 'react-dom';
+
+import HelloWorldContainer from '../../app/components/HelloWorldContainer';
+
+/*
+ *  Export a function that returns a ReactComponent, depending on a store named SharedReduxStore.
+ *  This is used for the client rendering hook after the page html is rendered.
+ *  React will see that the state is the same and not do anything.
+ */
+export default (props, _railsContext, domNodeId) => {
+  const render = props.prerender ? ReactDOM.hydrate : ReactDOM.render;
+  // eslint-disable-next-line no-param-reassign
+  delete props.prerender;
+
+  // This is where we get the existing store.
+  const store = ReactOnRails.getStore('SharedReduxStore');
+
+  // renderApp is a function required for hot reloading. see
+  // https://github.com/retroalgic/react-on-rails-hot-minimal/blob/master/client/src/entry.js
+
+  // Provider uses this.props.children, so we're not typical React syntax.
+  // This allows redux to add additional props to the HelloWorldContainer.
+  const renderApp = (Component) => {
+    const element = (
+      <Provider store={store}>
+        <Component />
+      </Provider>
+    );
+    render(element, document.getElementById(domNodeId));
+  };
+
+  renderApp(HelloWorldContainer);
+
+  if (module.hot) {
+    module.hot.accept(['../components/HelloWorldContainer'], () => {
+      renderApp(HelloWorldContainer);
+    });
+  }
+};