ExpectThunk proposal

ReSwift-Thunk.xcodeproj/project.pbxproj

@@ -13,6 +13,7 @@
 		65A3D6F0218B8A300075CB92 /* Thunk.swift in Sources */ = {isa = PBXBuildFile; fileRef = 65A3D6EF218B8A300075CB92 /* Thunk.swift */; };
 		65A3D6F3218C91F20075CB92 /* ReSwift.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 65A3D6F2218C91F20075CB92 /* ReSwift.framework */; };
 		65A3D6F5218C92420075CB92 /* createThunksMiddleware.swift in Sources */ = {isa = PBXBuildFile; fileRef = 65A3D6F4218C92420075CB92 /* createThunksMiddleware.swift */; };
+		D28E4F562214F37100DEFA7D /* ExpectThunk.swift in Sources */ = {isa = PBXBuildFile; fileRef = D28E4F552214F37100DEFA7D /* ExpectThunk.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -35,6 +36,7 @@
 		65A3D6EF218B8A300075CB92 /* Thunk.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Thunk.swift; sourceTree = "<group>"; };
 		65A3D6F2218C91F20075CB92 /* ReSwift.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = ReSwift.framework; path = Carthage/Build/iOS/ReSwift.framework; sourceTree = "<group>"; };
 		65A3D6F4218C92420075CB92 /* createThunksMiddleware.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = createThunksMiddleware.swift; sourceTree = "<group>"; };
+		D28E4F552214F37100DEFA7D /* ExpectThunk.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ExpectThunk.swift; sourceTree = "<group>"; };
 		D4286E7721EFED3F00D5749B /* CHANGELOG.md */ = {isa = PBXFileReference; lastKnownFileType = net.daringfireball.markdown; path = CHANGELOG.md; sourceTree = "<group>"; };
 		D4286E7821EFED4D00D5749B /* README.md */ = {isa = PBXFileReference; lastKnownFileType = net.daringfireball.markdown; path = README.md; sourceTree = "<group>"; };
 /* End PBXFileReference section */
@@ -94,6 +96,7 @@
 		65A3D6E2218B89A60075CB92 /* ReSwift-ThunkTests */ = {
 			isa = PBXGroup;
 			children = (
+				D28E4F552214F37100DEFA7D /* ExpectThunk.swift */,
 				65A3D6E3218B89A60075CB92 /* Tests.swift */,
 				65A3D6E5218B89A60075CB92 /* Info.plist */,
 			);
@@ -227,6 +230,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				65A3D6E4218B89A60075CB92 /* Tests.swift in Sources */,
+				D28E4F562214F37100DEFA7D /* ExpectThunk.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

ReSwift-ThunkTests/ExpectThunk.swift

@@ -0,0 +1,70 @@
+//
+//  ExpectThunk.swift
+//  ReSwift-Thunk-Tests
+//
+//  Created by Jason Prasad on 2/13/19.
+//  Copyright © 2019 ReSwift. All rights reserved.
+//
+
+import XCTest
+import ReSwift
+
+@testable import ReSwiftThunk
+
+// TODO: no longer allow subclassing
+public class ExpectThunk<State: StateType> {
+    public typealias ActionAssertion = (Action) -> Void
+    private var dispatch: DispatchFunction {
+        return { action in
+            let actionAssertion = self.actionAssertions.remove(at: 0)
+            actionAssertion(action)
+            if self.actionAssertions.count == 0 {
+                self.expectation.fulfill()
+            }
+        }
+    }
+    private var actionAssertions = [ActionAssertion]()
+    private var expectedStates = [State]()
+    private var expectation: XCTestExpectation
+    private var getState: () -> State? {
+        return {
+            if self.expectedStates.count > 0 {
+                return self.expectedStates.removeFirst()
+            } else {
+                return nil
+            }
+        }
+    }
+    private let thunk: Thunk<State>
+    public init(_ thunk: Thunk<State>, description: String? = nil) {
+        self.thunk = thunk
+        expectation = XCTestExpectation(description: description ?? "\(ExpectThunk.self)")
+    }
+}
+
+extension ExpectThunk {
+    public func dispatches<A: Action & Equatable>(_ expected: A, file: StaticString = #file, line: UInt = #line) -> Self {
+        actionAssertions.append({ received in
+            XCTAssert(received as? A == expected, "dispatched action does not equal expected: \(received) \(expected)", file: file, line: line)
+        })
+        return self
+    }
+    public func dispatches(_ matcher: @escaping ActionAssertion) -> Self {
+        actionAssertions.append(matcher)
+        return self
+    }
+}
+
+extension ExpectThunk {
+    func getsState(_ state: State) -> Self {
+        expectedStates.append(state)
+        return self
+    }
+}
+
+extension ExpectThunk {
+    func run() -> XCTestExpectation {
+        thunk.body(dispatch, getState)
+        return expectation
+    }
+}

ReSwift-ThunkTests/Tests.swift

@@ -12,7 +12,8 @@ import XCTest
 import ReSwift
 
 private struct FakeState: StateType {}
-private struct FakeAction: Action {}
+private struct FakeAction: Action, Equatable {}
+private struct AnotherFakeAction: Action, Equatable {}
 private func fakeReducer(action: Action, state: FakeState?) -> FakeState {
     return state ?? FakeState()
 }
@@ -58,4 +59,38 @@ class Tests: XCTestCase {
         store.dispatch(thunk)
         XCTAssertTrue(thunkBodyCalled)
     }
+
+    func testExpectThunk() {
+        let thunk = Thunk<FakeState> { dispatch, getState in
+            dispatch(FakeAction())
+            XCTAssertNotNil(getState())
+            DispatchQueue.global().asyncAfter(deadline: DispatchTime.now() + 0.5) {
+                dispatch(AnotherFakeAction())
+                XCTAssertNotNil(getState())
+                XCTAssertNil(getState())
+            }
+            dispatch(FakeAction())
+        }
+        let expect = ExpectThunk<FakeState>(thunk)
+            .dispatches(FakeAction())
+            .getsState(FakeState())
+            .dispatches {
+                XCTAssert($0 as? FakeAction == FakeAction())
+            }
+            .dispatches(AnotherFakeAction())
+            .getsState(FakeState())
+            .run()
+        /* NOTE: this will fail as it asserts order!
+         let expect = ExpectThunk<FakeState>(thunk)
+         .dispatches(FakeAction())
+         .getsState(FakeState())
+         .dispatches(AnotherFakeAction())
+         .dispatches {
+            XCTAssert($0 as? FakeAction == FakeAction())
+         }
+         .getsState(FakeState())
+         .run()
+         */
+        wait(for: [expect], timeout: 1.0)
+    }
 }