test: expand coverage, dedupe data-driven tests, extract shared WebTestCase base (#201)

* test: expand coverage, dedupe data-driven tests, extract shared WebTestCase base

- Add #[CoversClass] to Base64Test and FilenameSanitizerTest
- Merge near-duplicate test methods into #[DataProvider] cases across
  ResetPasswordControllerTest, SettingsControllerTest, ClaimSeasonCommandTest,
  FilenameSanitizerTest, Base64Test, and SeasonRepositoryTest
- Add integration tests for previously untested controllers: public
  QuizController (quiz-taking flow), LoginController, RegistrationController,
  EliminationController, and PrepareEliminationController
- Add unit tests for Elimination and BankQuestion entity logic
- Extract shared WebTestCase setup/helpers (client, entityManager, login,
  entity lookups, CSRF token scraping) into AbstractControllerWebTestCase,
  removing duplicated boilerplate from all 14 WebTestCase files

* test: address PR review feedback

- Scope AbstractControllerWebTestCase::getCandidate/getQuizByName by
  season code (both Candidate and Quiz are only unique per season, not
  system-wide) and add a CandidateRepository regression test guarding
  against same-named candidates in different seasons
- Add missing entityManager->clear() before verifying DB state after a
  POST in PrepareEliminationControllerTest and QuestionBankControllerTest
- Add non-owner denial tests for BackofficeController::exportQuiz and
  QuizQuestionController::edit/reorder, which had IsGranted checks with
  no test coverage

* ci: publish PHPUnit coverage to GitHub code coverage

- Generate a Cobertura report alongside the existing JUnit report and
  upload it with actions/upload-code-coverage so coverage shows up on
  PRs and the default branch via GitHub's code coverage feature
- Add a step to copy both reports out of the php container before
  publishing them, since var/ is a Docker volume (see the Dockerfile's
  VOLUME /app/var/) and isn't bind-mounted to the runner — this also
  fixes the existing JUnit report publishing step, which was silently
  looking at a path that never had contets on the runner

* ci: fix coverage report paths and tolerate Code Quality not yet enabled

- Write PHPUnit's JUnit and Cobertura reports to reports/ instead of
  var/, since var/ is a Docker volume (Dockerfile's VOLUME /app/var/)
  that isn't bind-mounted to the runner - reports written there never
  reached the host, which is also why the prior junit.xml publish step
  had nothing to read. reports/ is a plain path under the project's
  bind mount, so no extra copy-out step is needed
- Set fail-on-error: false on the coverage upload step: it 404s until
  "Code Quality" is turned on for the repo under Settings > Code
  security > Code quality, a one-time manual step

.github/workflows/ci.yml

@@ -123,6 +123,7 @@ jobs:
       checks: write
       pull-requests: write
       contents: read
+      code-quality: write
     steps:
       - name: Checkout
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
@@ -150,13 +151,26 @@ jobs:
       - name: Load fixtures
         run: docker compose exec -T php bin/console -e test doctrine:fixtures:load --no-interaction --group=test
       - name: Run PHPUnit
-        run: docker compose exec -T -e MAILER_DSN=null://null php vendor/bin/phpunit --log-junit var/phpunit/junit.xml
+        # Reports are written outside var/ since var/ is a Docker volume (see the Dockerfile's
+        # VOLUME /app/var/) and isn't bind-mounted to the runner, unlike the rest of the project.
+        run: docker compose exec -T -e MAILER_DSN=null://null php vendor/bin/phpunit --log-junit reports/junit.xml --coverage-cobertura reports/coverage/cobertura.xml
       - name: Publish PHPUnit test results
         if: always()
         uses: mikepenz/action-junit-report@d9f48fc87bc235f7e214acf696ca5abc0a986f16 # v6
         with:
-          report_paths: var/phpunit/junit.xml
+          report_paths: reports/junit.xml
           check_name: PHPUnit
+      - name: Upload code coverage
+        # Requires "Code Quality" to be enabled for this repository under
+        # Settings > Code security > Code quality; fail-on-error is false so CI
+        # doesn't go red before that one-time, manual repository setting is turned on.
+        if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository
+        uses: actions/upload-code-coverage@82c7aee3fb2ad768e00b00a0a8d749c5815085b6 # v1
+        with:
+          file: reports/coverage/cobertura.xml
+          language: PHP
+          label: phpunit
+          fail-on-error: false
       - name: Doctrine Schema Validator
         run: docker compose exec -T php bin/console -e test doctrine:schema:validate