SharedAsyncSequenceTests

SharedAsyncSequenceTests.swift

func testListeningUpdates() async throws {
        let controller = SequenceController<Int>()
        let sequence = AsyncStream<Int> { [controller] continuation in
            controller.onPublishElement = {
                continuation.yield($0)
            }
            controller.onFinish = {
                continuation.finish()
            }
        }
        .shared()
        
        final class ItemsHolder: @unchecked Sendable {
            var values: [Int] = []
        }
        let itemsHolder1 = ItemsHolder()
        let itemsHolder2 = ItemsHolder()
        let itemsHolder3 = ItemsHolder()
        
        let stream1 = sequence
        let stream2 = sequence
        let stream3 = SharedAsyncSequence(sequence)
        
        
        Task.detached {
            try await Task.sleep(nanoseconds: 100_000_000)
            controller.onPublishElement!(1)
            try await Task.sleep(nanoseconds: 100_000_000)
            controller.onPublishElement!(5)
            try await Task.sleep(nanoseconds: 100_000_000)
            controller.onPublishElement!(23)
            try await Task.sleep(nanoseconds: 100_000_000)
            controller.onFinish!()
        }
        
        try await withThrowingTaskGroup(of: Void.self) { [stream1, stream2, stream3] group in
            group.addTask {
                for try await value in stream1 {
                    itemsHolder1.values.append(value)
                }
            }
            group.addTask {
                for try  await value in stream2 {
                    itemsHolder2.values.append(value)
                }
            }
            group.addTask {
                for try  await value in stream3 {
                    itemsHolder3.values.append(value)
                }
            }
            try await group.waitForAll()
        }
        
        XCTAssert(itemsHolder1.values == [1, 5, 23])
        XCTAssert(itemsHolder2.values == [1, 5, 23])
        XCTAssert(itemsHolder3.values == [1, 5, 23])
    }
    
    final class SequenceController<Element> {
        var onPublishElement: ((Element) -> Void)? = nil
        var onFinish: (() -> Void)? = nil
    }