[build-utils] Handle case of not having lockfile (#11697)

In the scenario where we don't have a lockfile, cliType was detected by build utils as npm regardless of what's set in corepack. This fixes that.

.changeset/tender-bags-tell.md

@@ -0,0 +1,6 @@
+---
+"@vercel/build-utils": patch
+"vercel": patch
+---
+
+[built-utils] Handle case of not having lockfile when corepack is enabled

packages/build-utils/src/fs/run-user-scripts.ts

@@ -353,7 +353,9 @@ export async function scanParentDirs(
     // TODO: read "bun-lockfile-format-v0"
     lockfileVersion = 0;
   } else {
-    cliType = 'npm';
+    cliType = packageJson
+      ? detectPackageManagerNameWithoutLockfile(packageJson)
+      : 'npm';
   }
 
   const packageJsonPath = pkgJsonPath || undefined;
@@ -366,6 +368,37 @@ export async function scanParentDirs(
   };
 }
 
+function detectPackageManagerNameWithoutLockfile(packageJson: PackageJson) {
+  const packageJsonPackageManager = packageJson.packageManager;
+  if (usingCorepack(process.env, packageJsonPackageManager)) {
+    const corepackPackageManager = validateVersionSpecifier(
+      packageJsonPackageManager as string
+    );
+    switch (corepackPackageManager?.packageName) {
+      case 'npm':
+      case 'pnpm':
+      case 'yarn':
+      case 'bun':
+        return corepackPackageManager.packageName;
+      case undefined:
+        return 'npm';
+      default:
+        throw new Error(
+          `Unknown package manager "${corepackPackageManager?.packageName}". Change your package.json "packageManager" field to a known package manager.`
+        );
+    }
+  }
+  return 'npm';
+}
+
+function usingCorepack(
+  env: { [x: string]: string | undefined },
+  packageJsonPackageManager: string | undefined
+) {
+  const corepackFlagged = env.ENABLE_EXPERIMENTAL_COREPACK === '1';
+  return corepackFlagged && Boolean(packageJsonPackageManager);
+}
+
 export async function walkParentDirs({
   base,
   start,
@@ -557,8 +590,7 @@ export function getEnvForPackageManager({
   nodeVersion: NodeVersion | undefined;
   env: { [x: string]: string | undefined };
 }) {
-  const corepackFlagged = env.ENABLE_EXPERIMENTAL_COREPACK === '1';
-  const corepackEnabled = corepackFlagged && Boolean(packageJsonPackageManager);
+  const corepackEnabled = usingCorepack(env, packageJsonPackageManager);
 
   const {
     detectedLockfile,
@@ -753,6 +785,39 @@ export function getPathOverrideForPackageManager({
   }
 }
 
+function validateVersionSpecifier(version: string) {
+  if (!version) {
+    return undefined;
+  }
+
+  const [before, after, ...extra] = version.split('@');
+
+  if (extra.length) {
+    // should not have more than one `@`
+    return undefined;
+  }
+
+  if (!before) {
+    // should have a package before the `@`
+    return undefined;
+  }
+
+  if (!after) {
+    // should have a version after the `@`
+    return undefined;
+  }
+
+  if (!validRange(after)) {
+    // the version after the `@` should be a valid semver value
+    return undefined;
+  }
+
+  return {
+    packageName: before,
+    packageVersionRange: after,
+  };
+}
+
 /**
  * Helper to get the binary paths that link to the used package manager.
  * Note: Make sure it doesn't contain any `console.log` calls.

packages/cli/test/integration-1.test.ts

@@ -263,6 +263,7 @@ test('[vc build] should build project with corepack and select pnpm@7.1.0', asyn
       path.join(directory, '.vercel/cache/corepack')
     );
     expect(contents).toEqual(['home', 'shim']);
+    expect(output.stdout).toMatch(/Running "pnpm run build"/gm);
   } finally {
     delete process.env.ENABLE_EXPERIMENTAL_COREPACK;
   }
@@ -291,6 +292,7 @@ test('[vc build] should build project with corepack and select yarn@2.4.3', asyn
       path.join(directory, '.vercel/cache/corepack')
     );
     expect(contents).toEqual(['home', 'shim']);
+    expect(output.stdout).toMatch(/Running "yarn run build"/gm);
   } finally {
     delete process.env.ENABLE_EXPERIMENTAL_COREPACK;
   }