fix(billing): subscriptions test hardcodes plan: 'starter' — breaks plan-renamed downstream

[PierreBrisorgueil]

Problem

The new tests added in PR #4063 to src/modules/billing/tests/billing.subscriptions.component.unit.tests.js hardcode plan: 'starter' in the fixture for the new "Change Plan" CTA suite (status and paid plan CTAs describe block).

This breaks any downstream project that overrides billing.static-content.plans with their own plan IDs. Example: trawl_vue overrides plans to free / growth / pro, so availablePlanIds.indexOf('starter') returns -1, canUpgrade is false, and the test asserting "Change Plan" fails.

FAIL  src/modules/billing/tests/billing.subscriptions.component.unit.tests.js > BillingSubscriptionsComponent — status and paid plan CTAs > labels the paid plan upgrade CTA as Change Plan when a higher plan exists
AssertionError: expected 'Current PlanStatus:active Next billin…' to contain 'Change Plan'

Expected: "Change Plan"
Received: "Current PlanStatus:active Next billing date: May 3, 2026 Manage Subscription"

Affected file(s)

• src/modules/billing/tests/billing.subscriptions.component.unit.tests.js — two new tests in the "status and paid plan CTAs" describe block use plan: 'starter' (line ~343) and plan: 'pro' (line ~351). The 'pro' line happens to work because trawl also has 'pro' as the highest tier, but it's coincidental.

Steps to reproduce

cd trawl_vue
git fetch devkit-vue
git merge devkit-vue/master
NODE_ENV=trawl npm run test:unit -- src/modules/billing/tests/billing.subscriptions.component.unit.tests.js
# 1 failure

Suggested fix

Derive plan IDs dynamically from plansConfig so tests are portable to any plan rename. Already applied locally on trawl_vue — happy to PR upstream:

import { plans as plansConfig } from '../config/billing.static-content';

const paidPlanWithHigher = plansConfig
  .map((p) => p.id || p.planId)
  .filter(Boolean)
  .find((id, idx, arr) => id !== 'free' && idx < arr.length - 1) || 'starter';
const highestPlan = plansConfig
  .map((p) => p.id || p.planId)
  .filter(Boolean)
  .at(-1) || 'pro';

Then use paidPlanWithHigher and highestPlan in the new test fixtures.

Context

Found during /update-stack on trawl_vue (PR absorbing devkit Vue #4062 + #4063).
Per feedback_update_stack_theirs_wipes_patches, this kind of stack-coupled
test data drift is the recurring sharp edge — pushing the fix upstream
removes a permanent merge friction.