From c9e2c75aa7d08bc745193e6dd9fd52831a2c483f Mon Sep 17 00:00:00 2001
From: Hendrik Liebau <mail@hendrik-liebau.de>
Date: Mon, 17 Feb 2025 10:18:48 +0100
Subject: [PATCH] Fix runtime error in `writeConfigurationDefaults`

Follow-up for #74674

When running `pnpm next build` or `pnpm next dev` with a test app in the
Next.js repo, we patch the app's `tsconfig.json` to exclude the test
files from the program, because those are already covered by the root
`tsconfig.json`.

The code to suppress logging this action had a bug where we tried to
remove the action from the list of `requiredActions` even if it wasn't
added, resulting in the following runtime error:

```
Cannot read properties of undefined (reading 'includes')
```

This could happen when the `requiredActions` array was empty but the
`suggestedActions` array was not.
---
 .../typescript/writeConfigurationDefaults.ts  | 28 ++++++++-----------
 1 file changed, 12 insertions(+), 16 deletions(-)

diff --git a/packages/next/src/lib/typescript/writeConfigurationDefaults.ts b/packages/next/src/lib/typescript/writeConfigurationDefaults.ts
index 1858bc174225a..cda8fcb658ad1 100644
--- a/packages/next/src/lib/typescript/writeConfigurationDefaults.ts
+++ b/packages/next/src/lib/typescript/writeConfigurationDefaults.ts
@@ -136,6 +136,9 @@ export function getRequiredConfiguration(
   return res
 }
 
+const localDevTestFilesExcludeAction =
+  'NEXT_PRIVATE_LOCAL_DEV_TEST_FILES_EXCLUDE'
+
 export async function writeConfigurationDefaults(
   ts: typeof import('typescript'),
   tsConfigPath: string,
@@ -328,9 +331,7 @@ export async function writeConfigurationDefaults(
     }
 
     if (hasUpdates) {
-      requiredActions.push(
-        'Local development only: Excluded test files from coverage'
-      )
+      requiredActions.push(localDevTestFilesExcludeAction)
     }
   }
 
@@ -338,17 +339,6 @@ export async function writeConfigurationDefaults(
     return
   }
 
-  if (process.env.NEXT_PRIVATE_LOCAL_DEV) {
-    // remove it from the required actions if it exists
-    if (
-      requiredActions[requiredActions.length - 1].includes(
-        'Local development only'
-      )
-    ) {
-      requiredActions.pop()
-    }
-  }
-
   await fs.writeFile(
     tsConfigPath,
     CommentJson.stringify(userTsConfig, null, 2) + os.EOL
@@ -386,14 +376,20 @@ export async function writeConfigurationDefaults(
     Log.info('')
   }
 
-  if (requiredActions.length) {
+  const requiredActionsToBeLogged = process.env.NEXT_PRIVATE_LOCAL_DEV
+    ? requiredActions.filter(
+        (action) => action !== localDevTestFilesExcludeAction
+      )
+    : requiredActions
+
+  if (requiredActionsToBeLogged.length) {
     Log.info(
       `The following ${white('mandatory changes')} were made to your ${cyan(
         'tsconfig.json'
       )}:\n`
     )
 
-    requiredActions.forEach((action) => Log.info(`\t- ${action}`))
+    requiredActionsToBeLogged.forEach((action) => Log.info(`\t- ${action}`))
 
     Log.info('')
   }