fix(core): handle packageManager property with createPackageJson (#26726)

This PR was originally authored by @stephenwade. It adds the `packageManager` property to the `createPackageJson` function that ensures the generated `package.json` uses the same package manager that was used when generating it.

## Current Behavior
<!-- This is the behavior we have today -->

## Expected Behavior
<!-- This is the behavior we should expect with the changes in this PR
-->

## Related Issue(s)
<!-- Please link the issue being fixed so it gets closed when this is
merged. -->

Fixes #

---------

Co-authored-by: Stephen Wade <stephen@stephenwade.me>
Co-authored-by: Stephen Wade <stephen.wade@avb.net>

packages/nx/src/plugins/js/package-json/create-package-json.spec.ts

@@ -397,7 +397,7 @@ describe('createPackageJson', () => {
     });
   });
 
-  describe('parsing "package.json" versions', () => {
+  describe('parsing "package.json"', () => {
     const appDependencies = [
       { source: 'app1', target: 'npm:@nx/devkit', type: 'static' },
       { source: 'app1', target: 'npm:typescript', type: 'static' },
@@ -654,6 +654,98 @@ describe('createPackageJson', () => {
         },
       });
     });
+
+    it('should add packageManager if missing', () => {
+      spies.push(
+        jest.spyOn(fs, 'existsSync').mockImplementation((path) => {
+          if (path === 'libs/lib1/package.json') {
+            return true;
+          }
+          if (path === 'package.json') {
+            return true;
+          }
+        })
+      );
+      spies.push(
+        jest
+          .spyOn(fileutilsModule, 'readJsonFile')
+          .mockImplementation((path) => {
+            if (path === 'package.json') {
+              return {
+                ...rootPackageJson(),
+                packageManager: 'yarn',
+              };
+            }
+            if (path === 'libs/lib1/package.json') {
+              return projectPackageJson();
+            }
+          })
+      );
+
+      expect(
+        createPackageJson('lib1', graph, {
+          root: '',
+        })
+      ).toEqual({
+        dependencies: {
+          random: '1.0.0',
+          typescript: '^4.8.4',
+        },
+        name: 'other-name',
+        packageManager: 'yarn',
+        version: '1.2.3',
+      });
+    });
+
+    it('should replace packageManager if not in sync with root and show warning', () => {
+      spies.push(
+        jest.spyOn(fs, 'existsSync').mockImplementation((path) => {
+          if (path === 'libs/lib1/package.json') {
+            return true;
+          }
+          if (path === 'package.json') {
+            return true;
+          }
+        })
+      );
+      const consoleWarnSpy = jest.spyOn(process.stdout, 'write');
+      spies.push(consoleWarnSpy);
+      spies.push(
+        jest
+          .spyOn(fileutilsModule, 'readJsonFile')
+          .mockImplementation((path) => {
+            if (path === 'package.json') {
+              return {
+                ...rootPackageJson(),
+                packageManager: 'yarn@1.2',
+              };
+            }
+            if (path === 'libs/lib1/package.json') {
+              return {
+                ...projectPackageJson(),
+                packageManager: 'yarn@4.3',
+              };
+            }
+          })
+      );
+
+      expect(
+        createPackageJson('lib1', graph, {
+          root: '',
+        })
+      ).toEqual({
+        dependencies: {
+          random: '1.0.0',
+          typescript: '^4.8.4',
+        },
+        name: 'other-name',
+        packageManager: 'yarn@1.2',
+        version: '1.2.3',
+      });
+      expect(JSON.stringify(consoleWarnSpy.mock.calls)).toMatch(
+        /Package Manager Mismatch/
+      );
+    });
   });
 });
 

packages/nx/src/plugins/js/package-json/create-package-json.ts

@@ -16,6 +16,7 @@ import {
   filterUsingGlobPatterns,
   getTargetInputs,
 } from '../../../hasher/task-hasher';
+import { output } from '../../../utils/output';
 
 interface NpmDeps {
   readonly dependencies: Record<string, string>;
@@ -43,7 +44,7 @@ export function createPackageJson(
   const projectNode = graph.nodes[projectName];
   const isLibrary = projectNode.type === 'lib';
 
-  const rootPackageJson = readJsonFile(
+  const rootPackageJson: PackageJson = readJsonFile(
     join(options.root ?? workspaceRoot, 'package.json')
   );
 
@@ -180,6 +181,22 @@ export function createPackageJson(
     packageJson.peerDependenciesMeta
   );
 
+  if (rootPackageJson.packageManager) {
+    if (
+      packageJson.packageManager &&
+      packageJson.packageManager !== rootPackageJson.packageManager
+    ) {
+      output.warn({
+        title: 'Package Manager Mismatch',
+        bodyLines: [
+          `The project ${projectName} has explicitly specified "packageManager" config of "${packageJson.packageManager}" but the workspace is using "${rootPackageJson.packageManager}".`,
+          `Please remove the project level "packageManager" config or align it with the workspace root package.json.`,
+        ],
+      });
+    }
+    packageJson.packageManager = rootPackageJson.packageManager;
+  }
+
   return packageJson;
 }