Fix: Allow mock.property() to work with process.env variables

[sakina1303]

Fix: Allow mock.property() to work with process.env variables

Description

This PR fixes a TypeError that occurs when using mock.property() from the node:test module on process.env properties.

Error before:
TypeError: 'process.env' does not accept an accessor(getter/setter) descriptor

Fix:
When the target is process.env, mock.property() now performs a direct value assignment instead of using an accessor descriptor.
This ensures environment variables can be safely mocked and restored without throwing errors.

Reproduction Steps

import { mock } from "node:test";

console.log(Object.getOwnPropertyDescriptor(process.env, "PATH"));
mock.property(process.env, "PATH", "foo");
console.log(process.env.PATH);

With this fix:
{ value: '/usr/local/bin:...', writable: true, enumerable: true, configurable: true }
foo

Tests Added:
Added a new test file:
test/parallel/test-env-mock-process-env.js

The test validates:

• The mock operation on process.env variables works correctly.
• The environment variable can be restored safely.

Example output:
Mocked process.env.TEST_ENV successfully
Restored original process.env.TEST_ENV

Checklist:

• [✅] Includes test coverage for the change.
• [✅] make -j4 test passes locally.
• [✅] No documentation changes required.
• [✅] Commit message follows Node.js guidelines.

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fixes #60486

[nodejs-github-bot]

Review requested:

• @nodejs/test_runner

[regseb]

The mock.property() method must return a ProxyConstructor, with the new condition it will return process.env (which isn't a ProxyConstructor).

The lib/test.js file no longer exports test functionality (test, mock...), and its content is identical to the new test/parallel/test-env-mock-process-env.js file (except comment line 24). This new file doesn't use the mock.property() method, so it cannot test the change made in that method.

🤨

[sakina1303]

Thanks for catching that, @regseb! I’ve updated the implementation so that the process.env case now correctly returns a ProxyConstructor instead of the environment object. Also cleaned up the test file to properly verify both the mocking and restoring behavior using mock.property(). Please have a look at the latest changes and let me know if any further improvements are needed.

[mcollina]

This seems very specific to process.env. What does it make this object special that prevents mocking? Can we have a generic system?

[codecov]

Codecov Report

❌ Patch coverage is 18.18182% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.58%. Comparing base (8ea8d4c) to head (e322698).
⚠️ Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/internal/test_runner/mock/mock.js	18.18%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #60499      +/-   ##
==========================================
+ Coverage   88.57%   88.58%   +0.01%     
==========================================
  Files         704      704              
  Lines      207828   207868      +40     
  Branches    40040    40052      +12     
==========================================
+ Hits       184079   184138      +59     
+ Misses      15802    15766      -36     
- Partials     7947     7964      +17     

Files with missing lines	Coverage Δ
lib/internal/test_runner/mock/mock.js	97.80% <18.18%> (-0.93%)	⬇️

... and 32 files with indirect coverage changes

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