| 1 | import { afterAll, assert, describe, it } from "@effect/vitest" |
| 2 | import { Context, Effect, Layer, Ref } from "effect" |
| 3 | |
| 4 | interface StateShape { |
| 5 | readonly id: number |
| 6 | readonly todos: Ref.Ref<Array<string>> |
| 7 | readonly migrated: Ref.Ref<boolean> |
| 8 | } |
| 9 | |
| 10 | class State extends Context.Service<State, StateShape>()("State") {} |
| 11 | |
| 12 | class TodoService extends Context.Service<TodoService, { |
| 13 | readonly stateId: Effect.Effect<number> |
| 14 | readonly migrated: Effect.Effect<boolean> |
| 15 | readonly add: (title: string) => Effect.Effect<void> |
| 16 | readonly list: Effect.Effect<Array<string>> |
| 17 | }>()("TodoService") {} |
| 18 | |
| 19 | describe("top-level it.layer isolation", () => { |
| 20 | let nextId = 0 |
| 21 | const observedStateIds: Array<number> = [] |
| 22 | |
| 23 | const baseLayer = Layer.effect(State)( |
| 24 | Effect.gen(function*() { |
| 25 | const id = ++nextId |
| 26 | const todos = yield* Ref.make<Array<string>>([]) |
| 27 | const migrated = yield* Ref.make(false) |
| 28 | return { id, todos, migrated } |
| 29 | }) |
| 30 | ) |
| 31 | |
| 32 | const migrationLayer = Layer.effectDiscard( |
| 33 | Effect.gen(function*() { |
| 34 | const state = yield* State |
| 35 | yield* Ref.set(state.migrated, true) |
| 36 | }) |
| 37 | ) |
| 38 | |
| 39 | const migratedLayer = Layer.merge( |
| 40 | baseLayer, |
| 41 | migrationLayer.pipe(Layer.provide(baseLayer)) |
| 42 | ) |
| 43 | |
| 44 | const inMemoryLayer = Layer.effect(TodoService)( |
| 45 | Effect.gen(function*() { |
| 46 | const state = yield* State |
| 47 | return { |
| 48 | stateId: Effect.succeed(state.id), |
| 49 | migrated: Ref.get(state.migrated), |
| 50 | add: (title: string) => Ref.update(state.todos, (todos) => [...todos, title]), |
| 51 | list: Ref.get(state.todos) |
| 52 | } as const |
| 53 | }) |
| 54 | ).pipe(Layer.provide(migratedLayer)) |
| 55 | |
| 56 | it.layer(inMemoryLayer)((it) => { |
| 57 | it.effect("first block mutates isolated state", () => |
| 58 | Effect.gen(function*() { |
| 59 | const service = yield* TodoService |
| 60 | const stateId = yield* service.stateId |
| 61 | const migrated = yield* service.migrated |
| 62 | |
| 63 | observedStateIds.push(stateId) |
| 64 | yield* service.add("write tests") |
| 65 | |
| 66 | assert.isTrue(migrated) |
| 67 | assert.deepStrictEqual(yield* service.list, ["write tests"]) |
| 68 | })) |
| 69 | }) |
| 70 | |
| 71 | it.layer(inMemoryLayer)((it) => { |
| 72 | it.effect("second block starts fresh", () => |
| 73 | Effect.gen(function*() { |
| 74 | const service = yield* TodoService |
| 75 | const stateId = yield* service.stateId |
| 76 | const migrated = yield* service.migrated |
| 77 | |
| 78 | observedStateIds.push(stateId) |
| 79 | |
| 80 | assert.isTrue(migrated) |
| 81 | assert.deepStrictEqual(yield* service.list, []) |
| 82 | |
| 83 | yield* service.add("ship feature") |
| 84 | assert.deepStrictEqual(yield* service.list, ["ship feature"]) |
| 85 | })) |
| 86 | }) |
| 87 | |
| 88 | it.layer(inMemoryLayer)((it) => { |
| 89 | it.effect("third block also starts fresh", () => |
| 90 | Effect.gen(function*() { |
| 91 | const service = yield* TodoService |
| 92 | const stateId = yield* service.stateId |
| 93 | const migrated = yield* service.migrated |
| 94 | |
| 95 | observedStateIds.push(stateId) |
| 96 | |
| 97 | assert.isTrue(migrated) |
| 98 | assert.deepStrictEqual(yield* service.list, []) |
| 99 | })) |
| 100 | }) |
| 101 | |
| 102 | afterAll(() => { |
| 103 | assert.deepStrictEqual(observedStateIds, [1, 2, 3]) |
| 104 | }) |
| 105 | }) |