Add comprehensive test suite for WorkflowGenerator

[tsavo-at-pieces]

Overview

The WorkflowGenerator class — which renders CI workflows for all consumer repos — has zero test coverage. This is the highest-priority gap in the package. The multi-platform feature (v0.11.0) shipped with no automated verification.

What Needs Tests

P0 — Must Have

1. validate() coverage — 6 validation rules, 0 tested

   • Missing dart_sdk, wrong type, missing features, wrong type
   • Invalid platforms entries, platforms as non-List
   • Invalid secrets type, personal_access_token_secret type
   • Empty platforms list (currently silent fallback to ubuntu)

2. loadCiConfig() coverage — 5 code paths, 0 tested

   • File missing → returns null
   • Valid JSON without ci section → returns null
   • Valid JSON with ci section → returns Map
   • Malformed JSON → throws StateError
   • ci not a Map → throws StateError

3. render() single vs multi-platform — the highest-risk path

   • No platforms key → single-platform analyze-and-test job on ubuntu
   • platforms: ["ubuntu"] → same single-platform output
   • platforms: ["ubuntu", "macos"] → multi-platform with analyze + test matrix
   • platforms: ["ubuntu", "macos-arm64", "macos-x64", "windows"] → 4-platform matrix

4. _preserveUserSections() round-trip — data loss prevention

   • Non-empty user sections survive regeneration
   • Empty user sections stay empty
   • Multiple independent sections preserved

5. Backward compatibility — config without platforms produces output identical to pre-v0.11.0

P1 — Should Have

6. Feature flag combinations (proto, lfs, format_check, analysis_cache, managed_analyze, managed_test)
7. Secrets env block rendering with and without secrets
8. Sub-packages rendering and filtering
9. Rendered YAML is syntactically valid (parse with package:yaml)
10. Platform alias mapping (macos = macos-arm64 → macos-latest, macos-x64 → macos-15-intel)
11. Multi-platform: proto/lfs steps only in analyze job, not test matrix
12. _processTemplated round-trip idempotency

Acceptance Criteria

• test/workflow_generator_test.dart created with all P0 tests
• All P1 tests added
• dart test passes from package directory
• No existing functionality broken

[tsavo-at-pieces]

Partially resolved on main in commit 1851a3d.

69 tests now cover all validate() rules (dart_sdk, features, platforms, secrets, PAT, line_length, sub_packages, runner_overrides) and all loadCiConfig() paths. Remaining P1 coverage for render() and _preserveUserSections() can be tracked separately if needed.