Stub the TypeSafe API in your tests without fixtures or a network.

Add plug to your test dependencies ({:plug, "~> 1.16", only: :test}), then build a test client and describe the answers you want by question id:

# test/test_helper.exs
ExUnit.start()

# in a test
setup :typesafe_stubs

test "routes billing tickets" do
  client = TypeSafe.Test.client()

  TypeSafe.Test.stub(client,
    dept: {:choice, :billing, 0.9},
    urgent: {:noul, 0.3},
    anger: {:score, 1, 0.8}
  )

  assert {:ok, result} = MyApp.Triage.run(client, "Where is my refund?")
  assert result.answers.dept.choice == :billing
end

The stub reads the questions in each request and builds a response the way the API would, so the decoded structs are identical to those from a real call: probabilities sum to one, Score answers carry level, label and levels, and keys come back as atoms or strings exactly as you sent them.

Answer specs

• {:noul, probability}
• {:choice, option, confidence} - option is one of the question's keys; the remaining probability is spread evenly across the other options
• {:score, level, confidence} - level is a 0-based index; the remaining probability is spread evenly across the other levels

A request that asks a question you did not stub raises, so a test cannot silently pass on a default answer.

Errors and models

TypeSafe.Test.stub_error(client, 429, %{"error" => "slow down"}, [{"retry-after", "1"}])
TypeSafe.Test.stub_models(client, [%{name: "jev-1.13.0", description: "...", release_date: "2026-01-01"}])

Concurrency

Stubs use Req.Test, which follows the ownership model of Mox: call Req.Test.set_req_test_from_context/1 in setup (or the typesafe_stubs/1 helper here) and stubs are private to each async test.