From 48ed97757dab49189b7fbe7f97ffdcc2b7e78962 Mon Sep 17 00:00:00 2001
From: Ethan Arrowood <ethan.arrowood@vercel.com>
Date: Thu, 5 May 2022 11:21:29 -0600
Subject: [PATCH] add check for packageManager field

---
 __tests__/installer.test.ts |  8 ++++----
 src/main.ts                 | 23 ++++++++++++++++++-----
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/__tests__/installer.test.ts b/__tests__/installer.test.ts
index 98cc10b3..b54bcfa2 100644
--- a/__tests__/installer.test.ts
+++ b/__tests__/installer.test.ts
@@ -89,19 +89,19 @@ describe('setup-node', () => {
     warningSpy = jest.spyOn(core, 'warning');
     cnSpy.mockImplementation(line => {
       // uncomment to debug
-      process.stderr.write('write:' + line + '\n');
+      // process.stderr.write('write:' + line + '\n');
     });
     logSpy.mockImplementation(line => {
       // uncomment to debug
-      process.stderr.write('log:' + line + '\n');
+      // process.stderr.write('log:' + line + '\n');
     });
     dbgSpy.mockImplementation(msg => {
       // uncomment to see debug output
-      process.stderr.write(msg + '\n');
+      // process.stderr.write(msg + '\n');
     });
     warningSpy.mockImplementation(msg => {
       // uncomment to debug
-      process.stderr.write('log:' + msg + '\n');
+      // process.stderr.write('log:' + msg + '\n');
     });
   });
 
diff --git a/src/main.ts b/src/main.ts
index 59a23a74..2fe3bb41 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -47,11 +47,24 @@ export async function run() {
     }
 
     if (cache && isCacheFeatureAvailable()) {
-      if (semver.gte(version, '14.19.0')) {
-        try {
-          core.info(await getCommandOutput('corepack enable'));
-        } catch (err) {
-          core.warning(`Failed to enable corepack. Error: ${err.message}`)
+      const pkgJsonPath = path.join(__dirname, '..', 'package.json');
+      try {
+        const stat = await fs.promises.stat(pkgJsonPath);
+        if (stat.isFile()) {
+          const packageJson = JSON.parse(await fs.promises.readFile(pkgJsonPath, 'utf8'))
+          const packageManager = packageJson.packageManager;
+
+          if (packageManager !== undefined && semver.gte(version, '14.19.0')) {
+            try {
+              core.info(await getCommandOutput('corepack enable'));
+            } catch (err) {
+              core.warning(`Failed to enable corepack. Error: ${err.message}`)
+            }
+          }
+        }
+      } catch (err) {
+        if (err instanceof Error && (err as NodeJS.ErrnoException).code === 'ENOENT') {
+          core.warning(`Cannot find package.json at path ${pkgJsonPath}`)
         }
       }
       const cacheDependencyPath = core.getInput('cache-dependency-path');