n8n/packages/testing/playwright/docs/ORCHESTRATION.md

Custom Test Orchestration

Capability-aware test distribution across CI shards.

How It Works

Step	What Happens
1. Discovery	pnpm janitor discover (AST-based, detects test.fixme()/test.skip() automatically)
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)

// 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)

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	Containers
'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 + VictoriaMetrics + Vector

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.

// 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).

Temporarily Disabling Tests

Use test.fixme() to mark tests that need fixing. The janitor's discover command detects test.fixme() and test.skip() calls via AST analysis and automatically excludes them from CI distribution.

// Individual test
test.fixme('broken test', async ({ n8n }) => {
  // Excluded from CI distribution automatically
});

// Entire describe block
test.describe('Feature', () => {
  test.fixme(); // Marks all tests in this block

  test('test 1', async ({ n8n }) => { ... });
  test('test 2', async ({ n8n }) => { ... });
});

Refreshing Metrics

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)

Architecture

janitor orchestrate (generic)          distribute-tests.mjs (n8n CI adapter)
┌──────────────────────────┐          ┌──────────────────────────┐
│ AST discovery            │          │ Calls janitor orchestrate│
│ Metrics loading          │   JSON   │ Maps capabilities →      │
│ Capability grouping      │ ──────→  │   Docker images          │
│ Group splitting          │          │ Adds container overhead  │
│ Greedy bin-packing       │          │ Outputs GH Actions matrix│
└──────────────────────────┘          └──────────────────────────┘

The janitor handles generic orchestration (works for any Playwright project). distribute-tests.mjs is n8n's CI adapter that maps capabilities to Docker images.

Scripts

Script	Purpose
scripts/distribute-tests.mjs	CI adapter — calls janitor, maps images, outputs matrix
scripts/fetch-currents-metrics.mjs	Fetches metrics from Currents API

Testing Locally

# Janitor orchestration (generic output)
pnpm janitor orchestrate --shards=14

# CI adapter (n8n-specific output with Docker images)
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 janitor test patterns in janitor.config.mjs
Unbalanced shards	Refresh metrics - durations may have drifted
Worker not reused	Use string capabilities like 'proxy', not inline objects