test: restore process.argv in the suite that overrides CONFIRM_DOWNGRADE

Per review: fix the leaking fixture at its source instead of compensating
in upgradePrompt.test.js — hdbInfoController.test.js now saves/restores
process.argv around its override, and the compensation filter is removed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FNbH9xnNHcd7V1a58ho2CJ

Author: heskew

DESIGN.md

@@ -30,7 +30,7 @@ To match v4: `OpenDBIObject` sets `randomAccessStructure = isPrimary`, and `Reco
 
 - The prompt's answer can be supplied non-interactively via `CONFIRM_DOWNGRADE` — env var or `--CONFIRM_DOWNGRADE` CLI arg; argv wins (`assignCMDENVVariables`). With no override and no TTY on stdin, the prompt throws instead of blocking on stdin forever (#2046 — services/CI hung with nothing in the log; the mismatch is also logged to hdb.log now).
 - Upgrades never prompt (see the rationale comment in `bin/upgrade.js`); only the downgrade direction confirms. `upgradeCertsPrompt()` on the 4.x upgrade path still has the block-on-stdin hazard.
-- Test-suite gotcha: `unitTests/dataLayer/hdbInfoController.test.js` pushes `--CONFIRM_DOWNGRADE yes` into `process.argv` in a `before()` without cleanup, so it leaks into every later test file in the mocha process; tests that exercise the prompt must scrub argv first (see `unitTests/upgrade/upgradePrompt.test.js`).
+- Test-suite gotcha: a suite that supplies the override via `process.argv` affects every later test file in the same mocha process — save and restore `process.argv` in `before`/`after` (see `unitTests/dataLayer/hdbInfoController.test.js`).
 
 ## getFromSource() timing: promise resolves before commit runs
 

unitTests/dataLayer/hdbInfoController.test.js

@@ -219,11 +219,18 @@ describe.skip('Test hdbInfoController module ', function () {
 			insert_stub.resolves();
 		});
 
+		let originalArgv;
+
 		before(() => {
 			version_stub = sandbox.stub(packageJson, 'version').get(() => '4.0.0');
 			hasUpgradesRequired_stub = sandbox.stub(directiveManager, 'hasUpgradesRequired').returns(true);
 			sandbox.stub().returns();
-			process.argv.push('--CONFIRM_DOWNGRADE', 'yes');
+			originalArgv = process.argv;
+			process.argv = [...process.argv, '--CONFIRM_DOWNGRADE', 'yes'];
+		});
+
+		after(() => {
+			process.argv = originalArgv;
 		});
 
 		it('getVersionUpdateInfo nominal test', async () => {

unitTests/upgrade/upgradePrompt.test.js

@@ -14,24 +14,16 @@ describe('forceDowngradePrompt — non-interactive starts', () => {
 	const upgradeObj = new UpgradeObject('5.2.0', '5.1.22');
 	let originalIsTTY;
 	let originalEnv;
-	let originalArgv;
 
 	beforeEach(() => {
 		originalIsTTY = process.stdin.isTTY;
 		originalEnv = process.env.CONFIRM_DOWNGRADE;
-		originalArgv = process.argv;
 		process.stdin.isTTY = false;
 		delete process.env.CONFIRM_DOWNGRADE;
-		// Other test files push --CONFIRM_DOWNGRADE into argv without cleanup; scrub the flag and
-		// its value so these tests control the override.
-		process.argv = process.argv.filter(
-			(arg, i, argv) => arg !== '--CONFIRM_DOWNGRADE' && argv[i - 1] !== '--CONFIRM_DOWNGRADE'
-		);
 	});
 
 	afterEach(() => {
 		process.stdin.isTTY = originalIsTTY;
-		process.argv = originalArgv;
 		if (originalEnv === undefined) delete process.env.CONFIRM_DOWNGRADE;
 		else process.env.CONFIRM_DOWNGRADE = originalEnv;
 	});