Flaky test: `lookupSingleWebFinger` depends on external server (hollo.social)

[dahlia]

The test for lookupSingleWebFinger in packages/cli/src/webfinger/mod.test.ts is flaky because it depends on the external remote server hollo.social. When this server is temporarily unavailable, the test fails with:

Error [NotFoundError]: Resource not found: @fedify@hollo.social
    at lookupSingleWebFinger (/home/runner/work/fedify/fedify/packages/cli/src/webfinger/action.ts:28:5)
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5) {
  resource: '@fedify@hollo.social'
}

Current implementation

The test (lines 73-79) makes real HTTP requests to external servers:

test("Test lookupSingleWebFinger", async () => {
  const aliases = (await Array.fromAsync(
    RESOURCES,
    (resource) => lookupSingleWebFinger({ resource }),
  )).map((w) => w?.aliases?.[0]);
  assert.deepEqual(aliases, ALIASES);
});

Where RESOURCES includes (lines 9-12):

• @hongminhee@hackers.pub
• @fedify@hollo.social

Problem

This approach has several issues:

1. Unreliability: External servers may be temporarily unavailable, causing intermittent test failures
2. Network dependency: Tests require internet connectivity and DNS resolution
3. Slowness: Real HTTP requests significantly slow down the test suite
4. Brittleness: Changes to the external server's configuration or data can break tests unexpectedly

Proposed solution

The test should be refactored to use one of the following approaches:

1. Mock server: Spin up a local HTTP server that responds to WebFinger queries with known test data
2. Mock HTTP client: Mock the underlying HTTP fetch calls to return pre-determined responses
3. Use @fedify/testing utilities: Leverage existing testing utilities from the @fedify/testing package if available

The ideal solution would be to create a minimal local ActivityPub/WebFinger server for testing purposes, ensuring tests are:

• Fast (no real network I/O)
• Reliable (no external dependencies)
• Deterministic (known test data)

Additional context

• This issue only affects the next branch (Fedify 2.0)
• The test is located at packages/cli/src/webfinger/mod.test.ts:73
• The implementation being tested is in packages/cli/src/webfinger/action.ts