Make the new XCTModify play nicely with non-exhaustive testing. (#1939)

* Make the new XCTModify play nicely with non-exhaustive testing.

* wip

* Update Tests/ComposableArchitectureTests/TestStoreNonExhaustiveTests.swift

Co-authored-by: Stephen Celis <[email protected]>

---------

Co-authored-by: Stephen Celis <[email protected]>

Author: mbrandonw

Package.resolved

@@ -20,7 +20,7 @@ let package = Package(
     .package(url: "https://github.com/apple/swift-docc-plugin", from: "1.0.0"),
     .package(url: "https://github.com/google/swift-benchmark", from: "0.1.0"),
     .package(url: "https://github.com/pointfreeco/combine-schedulers", from: "0.8.0"),
-    .package(url: "https://github.com/pointfreeco/swift-case-paths", from: "0.10.0"),
+    .package(url: "https://github.com/pointfreeco/swift-case-paths", from: "0.13.0"),
     .package(url: "https://github.com/apple/swift-collections", from: "1.0.2"),
     .package(url: "https://github.com/pointfreeco/swift-custom-dump", from: "0.7.0"),
     .package(url: "https://github.com/pointfreeco/swift-dependencies", from: "0.1.2"),

Package.swift

@@ -1,3 +1,4 @@
+@_spi(Internals) import CasePaths
 import Combine
 import CustomDump
 import Foundation
@@ -1168,6 +1169,13 @@ extension TestStore where ScopedState: Equatable {
   ) throws {
     let current = expected
     var expected = expected
+    let updateStateToExpectedResult = updateStateToExpectedResult.map { original in
+      { (state: inout ScopedState) in
+        try XCTModifyLocals.$isExhaustive.withValue(self.exhaustivity == .on) {
+          try original(&state)
+        }
+      }
+    }
 
     switch self.exhaustivity {
     case .on:
@@ -1745,6 +1753,14 @@ extension TestStore where ScopedState: Equatable {
     file: StaticString,
     line: UInt
   ) {
+    let updateStateToExpectedResult = updateStateToExpectedResult.map { original in
+      { (state: inout ScopedState) in
+        try XCTModifyLocals.$isExhaustive.withValue(self.exhaustivity == .on) {
+          try original(&state)
+        }
+      }
+    }
+
     guard !self.reducer.receivedActions.isEmpty else {
       XCTFail(
         failureMessage(),

Sources/ComposableArchitecture/TestStore.swift

@@ -684,6 +684,71 @@
       await store.receive(/NonExhaustiveReceive.Action.response2)
     }
 
+    func testXCTModifyExhaustive() async {
+      struct State: Equatable {
+        var child: Int? = 0
+        var count = 0
+      }
+      enum Action: Equatable { case tap, response }
+      let store = TestStore(
+        initialState: State(),
+        reducer: Reduce<State, Action> { state, action in
+          switch action {
+          case .tap:
+            state.count += 1
+            return .send(.response)
+          case .response:
+            state.count += 1
+            return .none
+          }
+        }
+      )
+
+      await store.send(.tap) { state in
+        state.count = 1
+        XCTExpectFailure {
+          XCTModify(&state.child, case: /.some) { _ in }
+        } issueMatcher: {
+          $0.compactDescription == """
+            XCTModify failed: expected "Int" value to be modified but it was unchanged.
+            """
+        }
+      }
+      await store.receive(.response) { state in
+        state.count = 2
+        XCTExpectFailure {
+          XCTModify(&state.child, case: /Optional.some) { _ in }
+        } issueMatcher: {
+          $0.compactDescription == """
+            XCTModify failed: expected "Int" value to be modified but it was unchanged.
+            """
+        }
+      }
+    }
+
+    func testXCTModifyNonExhaustive() async {
+      enum Action { case tap, response }
+      let store = TestStore(
+        initialState: Optional(1),
+        reducer: Reduce<Int?, Action> { state, action in
+          switch action {
+          case .tap:
+            return .send(.response)
+          case .response:
+            return .none
+          }
+        }
+      )
+      store.exhaustivity = .off
+
+      await store.send(.tap) {
+        XCTModify(&$0, case: /Optional.some) { _ in }
+      }
+      await store.receive(.response) {
+        XCTModify(&$0, case: /Optional.some) { _ in }
+      }
+    }
+
     // This example comes from Krzysztof Zabłocki's blog post:
     // https://www.merowing.info/exhaustive-testing-in-tca/
     func testKrzysztofExample1() {