From 0defcad1a21e22a0c5853bd4c960e3a7081021ed Mon Sep 17 00:00:00 2001
From: John White <750350+johnhwhite@users.noreply.github.com>
Date: Sun, 7 May 2023 16:09:13 -0400
Subject: [PATCH] fix(core): migrate using yarn when nxJson has another package
 manager configured (#16844)

(cherry picked from commit 065477610605d5799babc3ba78f26cdfe8737250)
---
 packages/nx/src/utils/package-manager.spec.ts | 43 +++++++++++++++++++
 packages/nx/src/utils/package-manager.ts      | 13 +++---
 2 files changed, 51 insertions(+), 5 deletions(-)
 create mode 100644 packages/nx/src/utils/package-manager.spec.ts

diff --git a/packages/nx/src/utils/package-manager.spec.ts b/packages/nx/src/utils/package-manager.spec.ts
new file mode 100644
index 0000000000000..4dce36fbcb132
--- /dev/null
+++ b/packages/nx/src/utils/package-manager.spec.ts
@@ -0,0 +1,43 @@
+jest.mock('fs');
+import * as fs from 'fs';
+import * as configModule from 'nx/src/config/configuration';
+import { detectPackageManager } from 'nx/src/utils/package-manager';
+
+describe('package-manager', () => {
+  it('should detect package manager in nxJson', () => {
+    jest.spyOn(configModule, 'readNxJson').mockReturnValueOnce({
+      cli: {
+        packageManager: 'pnpm',
+      },
+    });
+    const packageManager = detectPackageManager();
+    expect(packageManager).toEqual('pnpm');
+    expect(fs.existsSync).not.toHaveBeenCalled();
+  });
+
+  it('should detect yarn package manager from yarn.lock', () => {
+    jest.spyOn(configModule, 'readNxJson').mockReturnValueOnce({});
+    (fs.existsSync as jest.Mock).mockReturnValueOnce(true);
+    const packageManager = detectPackageManager();
+    expect(packageManager).toEqual('yarn');
+    expect(fs.existsSync).toHaveBeenNthCalledWith(1, 'yarn.lock');
+  });
+
+  it('should detect pnpm package manager from pnpm-lock.yaml', () => {
+    jest.spyOn(configModule, 'readNxJson').mockReturnValueOnce({});
+    (fs.existsSync as jest.Mock).mockImplementation((path) => {
+      return path === 'pnpm-lock.yaml';
+    });
+    const packageManager = detectPackageManager();
+    expect(packageManager).toEqual('pnpm');
+    expect(fs.existsSync).toHaveBeenCalledTimes(3);
+  });
+
+  it('should use npm package manager as default', () => {
+    jest.spyOn(configModule, 'readNxJson').mockReturnValueOnce({});
+    (fs.existsSync as jest.Mock).mockReturnValue(false);
+    const packageManager = detectPackageManager();
+    expect(packageManager).toEqual('npm');
+    expect(fs.existsSync).toHaveBeenCalledTimes(5);
+  });
+});
diff --git a/packages/nx/src/utils/package-manager.ts b/packages/nx/src/utils/package-manager.ts
index 8416d27d58fb1..ab23a024c99e4 100644
--- a/packages/nx/src/utils/package-manager.ts
+++ b/packages/nx/src/utils/package-manager.ts
@@ -30,11 +30,14 @@ export interface PackageManagerCommands {
  */
 export function detectPackageManager(dir: string = ''): PackageManager {
   const nxJson = readNxJson();
-  return nxJson.cli?.packageManager ?? existsSync(join(dir, 'yarn.lock'))
-    ? 'yarn'
-    : existsSync(join(dir, 'pnpm-lock.yaml'))
-    ? 'pnpm'
-    : 'npm';
+  return (
+    nxJson.cli?.packageManager ??
+    (existsSync(join(dir, 'yarn.lock'))
+      ? 'yarn'
+      : existsSync(join(dir, 'pnpm-lock.yaml'))
+      ? 'pnpm'
+      : 'npm')
+  );
 }
 
 /**