test: add ancestor package.json checks for tmpdir

Policy tests can fail if a `package.json` exists in any of the parent
directories above the test. The existing checks are done for the
ancestors of the test directory but some tests execute from the tmpdir.

PR-URL: #38285
Refs: #38088
Refs: #35600
Refs: #35633
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/common/README.md

@@ -370,10 +370,12 @@ const { spawn } = require('child_process');
 spawn(...common.pwdCommand, { stdio: ['pipe'] });
 ```
 
-### `requireNoPackageJSONAbove()`
+### `requireNoPackageJSONAbove([dir])`
 
-Throws an `AssertionError` if a `package.json` file is in any ancestor
-directory. Such files may interfere with proper test functionality.
+* `dir` [<string>][] default = \_\_dirname
+
+Throws an `AssertionError` if a `package.json` file exists in any ancestor
+directory above `dir`. Such files may interfere with proper test functionality.
 
 ### `runWithInvalidFD(func)`
 

test/common/index.js

@@ -708,8 +708,8 @@ function gcUntil(name, condition) {
   });
 }
 
-function requireNoPackageJSONAbove() {
-  let possiblePackage = path.join(__dirname, '..', 'package.json');
+function requireNoPackageJSONAbove(dir = __dirname) {
+  let possiblePackage = path.join(dir, '..', 'package.json');
   let lastPackage = null;
   while (possiblePackage !== lastPackage) {
     if (fs.existsSync(possiblePackage)) {

test/pummel/test-policy-integrity.js

@@ -76,6 +76,7 @@ function newTestId() {
   return nextTestId++;
 }
 tmpdir.refresh();
+common.requireNoPackageJSONAbove(tmpdir.path);
 
 let spawned = 0;
 const toSpawn = [];