TestClient class final

Drives a Router through either an in-process handler or real HTTP.

// In-process — no socket, sub-millisecond.
final client = TestClient(router);

// Real HTTP on port 0 — catches wire-level bugs.
final client = await TestClient.serve(router);

final response = await (client.post('/orders')
    ..bearer('tok')
    ..json({'item': 'shirt', 'quantity': 2})
    ..expectSuccess())
    .send();
response
    ..assertCreated()
    ..assertJsonContains({'item': 'shirt'});