# Custom Test Orchestration

Capability-aware test distribution across CI shards.

## How It Works

| Step | What Happens |
|------|--------------|
| 1. Discovery | `pnpm playwright test --list --project="multi-main:e2e"` |
| 2. Metrics | Get `avgDuration` per spec from Currents (last 30 days) |
| 3. Default | Missing specs get **60s** default (accounts for container startup) |
| 4. Group | Group specs by `@capability:xxx` tag for worker reuse |
| 5. Effective Duration | Calculate actual time accounting for container reuse within groups |
| 6. Split | If a group exceeds **5 min**, split into sub-groups |
| 7. Bin Pack | Greedy assign groups + standard specs to lightest shard |

### Why Group by Capability?

Tests requiring containers (proxy, email, etc.) include ~20s startup overhead. When grouped on the same shard, only the first test pays this cost - the rest reuse the worker.

**Example:** 15 proxy tests across 8 shards = 8 container starts (160s). Grouped on 2 shards = 2 starts (40s). **Saves 120s.**

### Self-Balancing

Metrics auto-correct over time. As grouped tests run, they report actual execution time (not startup overhead), so future distributions become more accurate.

## Writing Tests with Capabilities

### 1. Use capability option (enables worker reuse)

```typescript
// String capability - maps to predefined config
test.use({ capability: 'proxy' });

// Custom config - full control over container settings
test.use({
  capability: {
    proxyServerEnabled: true,
    env: { MY_VAR: 'value' },
  },
});
```

### 2. Add @capability tag (required for orchestration grouping)

```typescript
test('My feature @capability:proxy', async ({ page }) => {
  // This test will be grouped with other proxy tests
});

// Or at describe level:
test.describe('Feature @capability:email', () => {
  // All tests inherit the tag
});
```

### Available Capabilities

| Capability | Tag | Container |
|------------|-----|-----------|
| `'proxy'` | `@capability:proxy` | Proxy server |
| `'email'` | `@capability:email` | Mailpit |
| `'source-control'` | `@capability:source-control` | Git server |
| `'task-runner'` | `@capability:task-runner` | Task runner |
| `'oidc'` | `@capability:oidc` | OIDC provider |
| `'observability'` | `@capability:observability` | VictoriaLogs |

## Modes vs Capabilities

**Capabilities** (`@capability:X`) are add-on features you can combine with any infrastructure:
- Use `test.use({ capability: 'proxy' })` to configure the worker
- Add-on containers (proxy, email, gitea, etc.) spin up alongside n8n

**Modes** (`@mode:X`) define the infrastructure configuration itself:
- `@mode:postgres` - n8n with PostgreSQL database (vs default sqlite)
- `@mode:queue` - n8n with EXECUTIONS_MODE=queue (workers via Bull, rarely used as tag)
- `@mode:multi-main` - n8n HA setup with leader election (implies queue mode)

Most e2e tests run against ALL modes via projects (`sqlite:e2e`, `postgres:e2e`, etc).
Use `@mode:X` only for tests that ONLY work with a specific infrastructure.

```typescript
// Capability - add-on feature
test.use({ capability: 'proxy' });
test('API mocking @capability:proxy', ...);

// Mode - infrastructure requirement (no test.use needed, project handles it)
test('Postgres-specific test @mode:postgres', ...);

// Combined - capability ON a specific mode
test.use({ capability: 'observability' });
test('Multi-main logs @capability:observability @mode:multi-main', ...);
```

Both `@capability:X` and `@mode:X` tests are skipped in local mode (they require containers).

## Refreshing Metrics

```bash
CURRENTS_API_KEY=<key> node packages/testing/playwright/scripts/fetch-currents-metrics.mjs --project=<id>
```

This fetches the last 30 days of test durations from Currents, aggregates by spec, and writes to `.github/test-metrics/playwright.json`.

**When to refresh:**
- Weekly (recommended)
- After significant test changes
- When adding new specs (optional - they get 60s default)

## Scripts

| Script | Purpose |
|--------|---------|
| `scripts/distribute-tests.mjs` | Distributes specs across shards |
| `scripts/fetch-currents-metrics.mjs` | Fetches metrics from Currents API |

### Testing Locally

```bash
# See distribution for 14 shards
node scripts/distribute-tests.mjs --matrix 14 --orchestrate

# Get specs for shard 0
node scripts/distribute-tests.mjs 14 0
```

## Troubleshooting

| Problem | Solution |
|---------|----------|
| Specs not running | Check path matches `playwright test --list` output |
| Unbalanced shards | Refresh metrics - durations may have drifted |
| Worker not reused | Use string capabilities like `'proxy'`, not inline objects |
