Addon Test: Add prerequisite check for MSW

code/addons/test/src/postinstall.ts

@@ -145,6 +145,16 @@ export default async function postInstall(options: PostinstallOptions) {
       `);
     }
 
+    const mswVersionSpecifier = await packageManager.getInstalledVersion('msw');
+    const coercedMswVersion = mswVersionSpecifier ? coerce(mswVersionSpecifier) : null;
+
+    if (coercedMswVersion && !satisfies(coercedMswVersion, '>=2.0.0')) {
+      reasons.push(dedent`
+        • The addon uses Vitest behind the scenes, which supports only version 2 and above of MSW. However, we have detected version ${picocolors.bold(coercedMswVersion.version)} in this project.
+        Please update the 'msw' package and try again.
+      `);
+    }
+
     if (info.frameworkPackageName === '@storybook/nextjs') {
       const nextVersion = await packageManager.getInstalledVersion('next');
       if (!nextVersion) {
@@ -159,6 +169,7 @@ export default async function postInstall(options: PostinstallOptions) {
       reasons.unshift(
         `Storybook Test's automated setup failed due to the following package incompatibilities:`
       );
+      reasons.push('--------------------------------');
       reasons.push(
         dedent`
           You can fix these issues and rerun the command to reinstall. If you wish to roll back the installation, remove ${picocolors.bold(colors.pink(ADDON_NAME))} from the "addons" array

code/lib/cli-storybook/src/add.ts

@@ -111,17 +111,19 @@ export async function add(
 
   let shouldAddToMain = true;
   if (checkInstalled(addonName, requireMain(configDir))) {
-    const { shouldForceInstall } = await prompts({
-      type: 'confirm',
-      name: 'shouldForceInstall',
-      message: `The Storybook addon "${addonName}" is already present in ${mainConfig}. Do you wish to install it again?`,
-    });
-
-    if (!shouldForceInstall) {
-      return;
-    }
-
     shouldAddToMain = false;
+    if (!yes) {
+      logger.log(`The Storybook addon "${addonName}" is already present in ${mainConfig}.`);
+      const { shouldForceInstall } = await prompts({
+        type: 'confirm',
+        name: 'shouldForceInstall',
+        message: `Do you wish to install it again?`,
+      });
+
+      if (!shouldForceInstall) {
+        return;
+      }
+    }
   }
 
   const main = await readConfig(mainConfig);