Fix Webpack aliasing

code/frameworks/nextjs/src/config/webpack.ts

@@ -2,7 +2,7 @@ import type { NextConfig } from 'next';
 import type { Configuration as WebpackConfig } from 'webpack';
 import { DefinePlugin } from 'webpack';
 
-import { addScopedAlias, resolveNextConfig } from '../utils';
+import { addScopedAlias, resolveNextConfig, setAlias } from '../utils';
 
 const tryResolve = (path: string) => {
   try {
@@ -20,33 +20,31 @@ export const configureConfig = async ({
   nextConfigPath?: string;
 }): Promise<NextConfig> => {
   const nextConfig = await resolveNextConfig({ nextConfigPath });
-  baseConfig.resolve ??= {};
-  baseConfig.resolve.alias ??= {};
-  const aliasConfig = baseConfig.resolve.alias;
 
   addScopedAlias(baseConfig, 'next/config');
+
+  // @ts-expect-error We know that alias is an object
+  if (baseConfig.resolve?.alias?.['react-dom']) {
+    // Removing the alias to react-dom to avoid conflicts with the alias we are setting
+    // because the react-dom alias is an exact match and we need to alias separate parts of react-dom
+    // in different places
+    // @ts-expect-error We know that alias is an object
+    delete baseConfig.resolve.alias?.['react-dom'];
+  }
+
   if (tryResolve('next/dist/compiled/react')) {
     addScopedAlias(baseConfig, 'react', 'next/dist/compiled/react');
   }
   if (tryResolve('next/dist/compiled/react-dom/cjs/react-dom-test-utils.production.js')) {
-    addScopedAlias(
+    setAlias(
       baseConfig,
       'react-dom/test-utils',
       'next/dist/compiled/react-dom/cjs/react-dom-test-utils.production.js'
     );
-  } else {
-    const name = 'react-dom/test-utils';
-    if (Array.isArray(aliasConfig)) {
-      aliasConfig.push({
-        name,
-        alias: name,
-      });
-    } else {
-      aliasConfig[name] = name;
-    }
   }
   if (tryResolve('next/dist/compiled/react-dom')) {
-    addScopedAlias(baseConfig, 'react-dom', 'next/dist/compiled/react-dom');
+    setAlias(baseConfig, 'react-dom$', 'next/dist/compiled/react-dom');
+    setAlias(baseConfig, 'react-dom/server', 'next/dist/compiled/react-dom/server');
   }
 
   setupRuntimeConfig(baseConfig, nextConfig);

code/frameworks/nextjs/src/utils.ts

@@ -27,23 +27,27 @@ export const resolveNextConfig = async ({
   return loadConfig(PHASE_DEVELOPMENT_SERVER, dir, undefined);
 };
 
-// This is to help the addon in development
-// Without it, webpack resolves packages in its node_modules instead of the example's node_modules
-export const addScopedAlias = (baseConfig: WebpackConfig, name: string, alias?: string): void => {
+export function setAlias(baseConfig: WebpackConfig, name: string, alias: string) {
   baseConfig.resolve ??= {};
   baseConfig.resolve.alias ??= {};
   const aliasConfig = baseConfig.resolve.alias;
 
-  const scopedAlias = scopedResolve(`${alias ?? name}`);
-
   if (Array.isArray(aliasConfig)) {
     aliasConfig.push({
       name,
-      alias: scopedAlias,
+      alias,
     });
   } else {
-    aliasConfig[name] = scopedAlias;
+    aliasConfig[name] = alias;
   }
+}
+
+// This is to help the addon in development
+// Without it, webpack resolves packages in its node_modules instead of the example's node_modules
+export const addScopedAlias = (baseConfig: WebpackConfig, name: string, alias?: string): void => {
+  const scopedAlias = scopedResolve(`${alias ?? name}`);
+
+  setAlias(baseConfig, name, scopedAlias);
 };
 
 /**
@@ -64,7 +68,7 @@ export const scopedResolve = (id: string): string => {
   let scopedModulePath;
 
   try {
-    // TODO: Remove in next major release (SB 8.0) and use the statement in the catch block per default instead
+    // TODO: Remove in next major release (SB 9.0) and use the statement in the catch block per default instead
     scopedModulePath = require.resolve(id, { paths: [resolve()] });
   } catch (e) {
     scopedModulePath = require.resolve(id);

code/renderers/react/src/act-compat.ts

@@ -10,10 +10,7 @@ declare const globalThis: {
 
 const reactAct =
   // @ts-expect-error act might not be available in some versions of React
-  typeof React.act === 'function'
-    ? // @ts-expect-error act might not be available in some versions of React
-      React.act
-    : DeprecatedReactTestUtils.act ?? (async (cb: () => Promise<void> | void) => cb());
+  typeof React.act === 'function' ? React.act : DeprecatedReactTestUtils.act;
 
 export function setReactActEnvironment(isReactActEnvironment: boolean) {
   globalThis.IS_REACT_ACT_ENVIRONMENT = isReactActEnvironment;