Testing your configuration

App-Compose checks the configuration on every .run():

• the same Task added twice
• two Wires writing into the same Tag
• a Task reading from a Tag that’s never wired
• an unused Wire

“Same” means the same instance, not the same name.

.guard() runs the same check stricter, in a test: unused Wires throw instead of warning. All others throw in both.

Guard reports the first error it finds — fix and re-run to see the next.

Writing the test

In any test framework, call .guard() and assert it doesn’t throw.

import { createWire, literal, compose, tag, createTask } from "@grlt-hub/app-compose"

const apiUrl = tag("apiUrl")

const auth = createTask({
  name: "auth",
  run: {
    context: { url: apiUrl.value },
    fn: ({ url }) => ({ token: "secret", url }),
  },
})

const dashboard = createTask({
  name: "dashboard",
  run: {
    context: { token: auth.result.token },
    fn: ({ token }) => console.log(`token=${token}`),
  },
})

const orphanTag = tag("orphan")

const app = compose()
  // 👇 comment out — apiUrl never gets wired
  .step(createWire({ from: literal("<url>"), to: apiUrl }))

  // 👇 uncomment — apiUrl wired twice
  // .step(createWire({ from: literal("<other-url>"), to: apiUrl }))

  .step(auth)

  // 👇 uncomment — auth registered twice
  // .step(auth)

  // 👇 uncomment — orphan Wire (nothing reads it)
  // .step(createWire({ from: literal(null), to: orphanTag }))

  .step(dashboard)

describe("app configuration", () => {
  it("is valid", () => {
    expect(() => app.guard()).not.toThrow()
  })
})