swift-composable-architecture-mirror/Sources/swift-composable-architecture-benchmark/StoreScope.swift

import Benchmark
import ComposableArchitecture

@Reducer
private struct Counter {
  typealias State = Int
  typealias Action = Bool
  var body: some Reducer<State, Action> {
    Reduce { state, action in
      if action {
        state += 1
        return .none
      } else {
        state -= 1
        return .none
      }
    }
  }
}

let storeScopeSuite = BenchmarkSuite(name: "Store scoping") { suite in
  var store = Store(initialState: 0) { Counter() }
  var viewStores: [ViewStore<Int, Bool>] = [ViewStore(store, observe: { $0 })]
  for _ in 1...4 {
    store = store.scope(state: { $0 }, action: { $0 })
    viewStores.append(ViewStore(store, observe: { $0 }))
  }
  let lastViewStore = viewStores.last!

  suite.benchmark("Nested store") {
    lastViewStore.send(true)
  }
}