ZcashLightClientKit/Tests/DarksideTests/BalanceTests.swift

//
//  BalanceTests.swift
//  ZcashLightClientKit-Unit-Tests
//
//  Created by Francisco Gindre on 4/28/20.
//

import Combine
import XCTest
@testable import TestUtils
@testable import ZcashLightClientKit

class BalanceTests: ZcashTestCase {
    let sendAmount = Zatoshi(1000)
    let defaultLatestHeight: BlockHeight = 663188
    let branchID = "2bb40e60"
    let chainName = "main"
    let network: ZcashNetwork = DarksideWalletDNetwork()

    var birthday: BlockHeight = 663150
    var sentTransactionExpectation = XCTestExpectation(description: "sent")
    var syncedExpectation = XCTestExpectation(description: "synced")
    var coordinator: TestCoordinator!
    var cancellables: [AnyCancellable] = []

    override func setUp() async throws {
        try await super.setUp()
        self.coordinator = try await TestCoordinator(
            container: mockContainer,
            walletBirthday: birthday,
            network: network
        )
        try coordinator.reset(saplingActivation: 663150, branchID: "e9ff75a6", chainName: "main")
    }

    override func tearDown() async throws {
        try await super.tearDown()
        let coordinator = self.coordinator!
        self.coordinator = nil
        cancellables = []

        try await coordinator.stop()
        try? FileManager.default.removeItem(at: coordinator.databases.fsCacheDbRoot)
        try? FileManager.default.removeItem(at: coordinator.databases.dataDB)
    }
    
    /**
    verify that when sending the maximum amount, the transactions are broadcasted properly
    */
    // FIXME [#783]: Fix test
    func disabled_testMaxAmountSend() async throws {
        let notificationHandler = SDKSynchonizerListener()
        let foundTransactionsExpectation = XCTestExpectation(description: "found transactions expectation")
        let transactionMinedExpectation = XCTestExpectation(description: "transaction mined expectation")
        
        // 0 subscribe to updated transactions events
        notificationHandler.subscribeToSynchronizer(coordinator.synchronizer)
        // 1 sync and get spendable funds
        try FakeChainBuilder.buildChain(darksideWallet: coordinator.service, branchID: branchID, chainName: chainName)
        
        try coordinator.applyStaged(blockheight: defaultLatestHeight + 10)
        
        sleep(1)
        let firstSyncExpectation = XCTestExpectation(description: "first sync expectation")
        
        do {
            try await coordinator.sync(
                completion: { _ in
                    firstSyncExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }

        await fulfillment(of: [firstSyncExpectation], timeout: 12)
        // 2 check that there are no unconfirmed funds
        
        let verifiedBalance: Zatoshi = try await coordinator.synchronizer.getShieldedVerifiedBalance()
        let totalBalance: Zatoshi = try await coordinator.synchronizer.getShieldedBalance()
        XCTAssertTrue(verifiedBalance > network.constants.defaultFee(for: defaultLatestHeight))
        XCTAssertEqual(verifiedBalance, totalBalance)
        
        let maxBalance = verifiedBalance - network.constants.defaultFee(for: defaultLatestHeight)
        
        // 3 create a transaction for the max amount possible
        // 4 send the transaction
        let spendingKey = coordinator.spendingKey

        var pendingTx: ZcashTransaction.Overview?
        do {
            let transaction = try await coordinator.synchronizer.sendToAddress(
                spendingKey: spendingKey,
                zatoshi: maxBalance,
                toAddress: try Recipient(Environment.testRecipientAddress, network: self.network.networkType),
                memo: try Memo(string: "this is a test")
            )
            pendingTx = transaction
            self.sentTransactionExpectation.fulfill()
        } catch {
            XCTFail("sendToAddress failed: \(error)")
        }

        await fulfillment(of: [sentTransactionExpectation], timeout: 20)
        guard let pendingTx else {
            XCTFail("transaction creation failed")
            return
        }
        
        notificationHandler.synchronizerMinedTransaction = { transaction in
            XCTAssertNotNil(transaction.rawID)
            XCTAssertNotNil(pendingTx.rawID)
            XCTAssertEqual(transaction.rawID, pendingTx.rawID)
            transactionMinedExpectation.fulfill()
        }
        
        // 5 apply to height
        // 6 mine the block
        guard let rawTx = try coordinator.getIncomingTransactions()?.first else {
            XCTFail("no incoming transaction after")
            return
        }
        
        let latestHeight = try await coordinator.latestHeight()
        let sentTxHeight = latestHeight + 1
        
        notificationHandler.transactionsFound = { txs in
            let foundTx = txs.first(where: { $0.rawID == pendingTx.rawID })
            XCTAssertNotNil(foundTx)
            XCTAssertEqual(foundTx?.minedHeight, sentTxHeight)
            
            foundTransactionsExpectation.fulfill()
        }
        try coordinator.stageBlockCreate(height: sentTxHeight, count: 100)
        sleep(1)
        try coordinator.stageTransaction(rawTx, at: sentTxHeight)
        try coordinator.applyStaged(blockheight: sentTxHeight)
        sleep(2) // add enhance breakpoint here
        let mineExpectation = XCTestExpectation(description: "mineTxExpectation")
        
        do {
            try await coordinator.sync(
                completion: { synchronizer in
                    let pendingEntity = try await synchronizer.allPendingTransactions().first(where: { $0.rawID == pendingTx.rawID })
                    XCTAssertNotNil(pendingEntity, "pending transaction should have been mined by now")
                    XCTAssertNotNil(pendingEntity?.minedHeight)
                    XCTAssertEqual(pendingEntity?.minedHeight, sentTxHeight)
                    mineExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }

        await fulfillment(of: [mineExpectation, transactionMinedExpectation, foundTransactionsExpectation], timeout: 5)
        
        // 7 advance to confirmation
        
        try coordinator.applyStaged(blockheight: sentTxHeight + 10)
        
        sleep(2)
        
        let confirmExpectation = XCTestExpectation(description: "confirm expectation")
        notificationHandler.transactionsFound = { txs in
            XCTFail("We shouldn't find any transactions at this point but found \(txs)")
        }
        notificationHandler.synchronizerMinedTransaction = { transaction in
            XCTFail("We shouldn't find any mined transactions at this point but found \(transaction)")
        }

        do {
            try await coordinator.sync(
                completion: { _ in
                    confirmExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }

        await fulfillment(of: [confirmExpectation], timeout: 5)
        
        let confirmedPending = try await coordinator.synchronizer.allPendingTransactions()
            .first(where: { $0.rawID == pendingTx.rawID })
        
        XCTAssertNil(confirmedPending, "pending, now confirmed transaction found")

        let expectedVerifiedBalance = try await coordinator.synchronizer.getShieldedVerifiedBalance()
        let expectedBalance = try await coordinator.synchronizer.getShieldedBalance()
        XCTAssertEqual(expectedBalance, .zero)
        XCTAssertEqual(expectedVerifiedBalance, .zero)
    }
    
    /**
    verify that when sending the maximum amount minus one zatoshi, the transactions are broadcasted properly
    */
    // FIXME [#781]: Fix test
    func disabled_testMaxAmountMinusOneSend() async throws {
        let notificationHandler = SDKSynchonizerListener()
        let foundTransactionsExpectation = XCTestExpectation(description: "found transactions expectation")
        let transactionMinedExpectation = XCTestExpectation(description: "transaction mined expectation")
        
        // 0 subscribe to updated transactions events
        notificationHandler.subscribeToSynchronizer(coordinator.synchronizer)
        // 1 sync and get spendable funds
        try FakeChainBuilder.buildChain(darksideWallet: coordinator.service, branchID: branchID, chainName: chainName)
        
        try coordinator.applyStaged(blockheight: defaultLatestHeight + 10)
        
        sleep(1)
        let firstSyncExpectation = XCTestExpectation(description: "first sync expectation")
        
        do {
            try await coordinator.sync(
                completion: { _ in
                    firstSyncExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }

        await fulfillment(of: [firstSyncExpectation], timeout: 12)
        // 2 check that there are no unconfirmed funds
        
        let verifiedBalance: Zatoshi = try await coordinator.synchronizer.getShieldedVerifiedBalance()
        let totalBalance: Zatoshi = try await coordinator.synchronizer.getShieldedBalance()
        XCTAssertTrue(verifiedBalance > network.constants.defaultFee(for: defaultLatestHeight))
        XCTAssertEqual(verifiedBalance, totalBalance)
        
        let maxBalanceMinusOne = verifiedBalance - network.constants.defaultFee(for: defaultLatestHeight) - Zatoshi(1)
        
        // 3 create a transaction for the max amount possible
        // 4 send the transaction
        let spendingKey = coordinator.spendingKey
        var pendingTx: ZcashTransaction.Overview?
        do {
            let transaction = try await coordinator.synchronizer.sendToAddress(
                spendingKey: spendingKey,
                zatoshi: maxBalanceMinusOne,
                toAddress: try Recipient(Environment.testRecipientAddress, network: self.network.networkType),
                memo: try Memo(string: "\(self.description) \(Date().description)")
            )
            pendingTx = transaction
            self.sentTransactionExpectation.fulfill()
        } catch {
            XCTFail("sendToAddress failed: \(error)")
        }

        await fulfillment(of: [sentTransactionExpectation], timeout: 20)
        guard let pendingTx else {
            XCTFail("transaction creation failed")
            return
        }
        
        notificationHandler.synchronizerMinedTransaction = { transaction in
            XCTAssertNotNil(transaction.rawID)
            XCTAssertNotNil(pendingTx.rawID)
            XCTAssertEqual(transaction.rawID, pendingTx.rawID)
            transactionMinedExpectation.fulfill()
        }
        
        // 5 apply to height
        // 6 mine the block
        guard let rawTx = try coordinator.getIncomingTransactions()?.first else {
            XCTFail("no incoming transaction after")
            return
        }
        
        let latestHeight = try await coordinator.latestHeight()
        let sentTxHeight = latestHeight + 1
        
        notificationHandler.transactionsFound = { txs in
            let foundTx = txs.first(where: { $0.rawID == pendingTx.rawID })
            XCTAssertNotNil(foundTx)
            XCTAssertEqual(foundTx?.minedHeight, sentTxHeight)
            
            foundTransactionsExpectation.fulfill()
        }
        try coordinator.stageBlockCreate(height: sentTxHeight, count: 100)
        sleep(1)
        try coordinator.stageTransaction(rawTx, at: sentTxHeight)
        try coordinator.applyStaged(blockheight: sentTxHeight)
        sleep(2) // add enhance breakpoint here
        let mineExpectation = XCTestExpectation(description: "mineTxExpectation")
        
        do {
            try await coordinator.sync(
                completion: { synchronizer in
                    let pendingEntity = try await synchronizer.allPendingTransactions().first(where: { $0.rawID == pendingTx.rawID })
                    XCTAssertNotNil(pendingEntity, "pending transaction should have been mined by now")
                    XCTAssertNotNil(pendingEntity?.minedHeight)
                    XCTAssertEqual(pendingEntity?.minedHeight, sentTxHeight)
                    mineExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }

        await fulfillment(of: [mineExpectation, transactionMinedExpectation, foundTransactionsExpectation], timeout: 5)
        
        // 7 advance to confirmation

        let advanceToConfirmationHeight = sentTxHeight + 10
        try coordinator.applyStaged(blockheight: advanceToConfirmationHeight)
        
        sleep(2)
        
        let confirmExpectation = XCTestExpectation(description: "confirm expectation")
        notificationHandler.transactionsFound = { txs in
            XCTFail("We shouldn't find any transactions at this point but found \(txs)")
        }
        notificationHandler.synchronizerMinedTransaction = { transaction in
            XCTFail("We shouldn't find any mined transactions at this point but found \(transaction)")
        }

        do {
            try await coordinator.sync(
                completion: { _ in
                    confirmExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }
        
        await fulfillment(of: [confirmExpectation], timeout: 5)
        
        let confirmedPending = try await coordinator.synchronizer
            .allPendingTransactions()
            .first(where: { $0.rawID == pendingTx.rawID })
        
        XCTAssertNil(confirmedPending, "pending, now confirmed transaction found")

        let expectedVerifiedBalance = try await coordinator.synchronizer.getShieldedVerifiedBalance()
        let expectedBalance = try await coordinator.synchronizer.getShieldedBalance()
        XCTAssertEqual(expectedBalance, Zatoshi(1))
        XCTAssertEqual(expectedVerifiedBalance, Zatoshi(1))
    }
    
    /**
    verify that when sending the a no change transaction, the transactions are broadcasted properly
    */
    // FIXME [#785]: Fix test
    func disabled_testSingleNoteNoChangeTransaction() async throws {
        let notificationHandler = SDKSynchonizerListener()
        let foundTransactionsExpectation = XCTestExpectation(description: "found transactions expectation")
        let transactionMinedExpectation = XCTestExpectation(description: "transaction mined expectation")
        
        // 0 subscribe to updated transactions events
        notificationHandler.subscribeToSynchronizer(coordinator.synchronizer)
        // 1 sync and get spendable funds
        try FakeChainBuilder.buildChain(darksideWallet: coordinator.service, branchID: branchID, chainName: chainName)
        
        try coordinator.applyStaged(blockheight: defaultLatestHeight + 10)
        
        sleep(1)
        let firstSyncExpectation = XCTestExpectation(description: "first sync expectation")
        
        do {
            try await coordinator.sync(
                completion: { _ in
                    firstSyncExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }

        await fulfillment(of: [firstSyncExpectation], timeout: 12)
        // 2 check that there are no unconfirmed funds
        
        let verifiedBalance: Zatoshi = try await coordinator.synchronizer.getShieldedVerifiedBalance()
        let totalBalance: Zatoshi = try await coordinator.synchronizer.getShieldedBalance()
        XCTAssertTrue(verifiedBalance > network.constants.defaultFee(for: defaultLatestHeight))
        XCTAssertEqual(verifiedBalance, totalBalance)
        
        let maxBalanceMinusOne = Zatoshi(100000) - network.constants.defaultFee(for: defaultLatestHeight)
        
        // 3 create a transaction for the max amount possible
        // 4 send the transaction
        let spendingKey = coordinator.spendingKey
        var pendingTx: ZcashTransaction.Overview?
        do {
            let transaction = try await coordinator.synchronizer.sendToAddress(
                spendingKey: spendingKey,
                zatoshi: maxBalanceMinusOne,
                toAddress: try Recipient(Environment.testRecipientAddress, network: self.network.networkType),
                memo: try Memo(string: "test send \(self.description) \(Date().description)")
            )
            pendingTx = transaction
            self.sentTransactionExpectation.fulfill()
        } catch {
            XCTFail("sendToAddress failed: \(error)")
        }

        await fulfillment(of: [sentTransactionExpectation], timeout: 20)
        guard let pendingTx else {
            XCTFail("transaction creation failed")
            return
        }
        
        notificationHandler.synchronizerMinedTransaction = { transaction in
            XCTAssertNotNil(transaction.rawID)
            XCTAssertNotNil(pendingTx.rawID)
            XCTAssertEqual(transaction.rawID, pendingTx.rawID)
            transactionMinedExpectation.fulfill()
        }
        
        // 5 apply to height
        // 6 mine the block
        guard let rawTx = try coordinator.getIncomingTransactions()?.first else {
            XCTFail("no incoming transaction after")
            return
        }
        
        let latestHeight = try await coordinator.latestHeight()
        let sentTxHeight = latestHeight + 1
        
        notificationHandler.transactionsFound = { txs in
            let foundTx = txs.first(where: { $0.rawID == pendingTx.rawID })
            XCTAssertNotNil(foundTx)
            XCTAssertEqual(foundTx?.minedHeight, sentTxHeight)
            
            foundTransactionsExpectation.fulfill()
        }
        try coordinator.stageBlockCreate(height: sentTxHeight, count: 100)
        sleep(1)
        try coordinator.stageTransaction(rawTx, at: sentTxHeight)
        try coordinator.applyStaged(blockheight: sentTxHeight)
        sleep(2) // add enhance breakpoint here
        let mineExpectation = XCTestExpectation(description: "mineTxExpectation")
        
        do {
            try await coordinator.sync(
                completion: { synchronizer in
                    let pendingEntity = try await synchronizer.allPendingTransactions().first(where: { $0.rawID == pendingTx.rawID })
                    XCTAssertNotNil(pendingEntity, "pending transaction should have been mined by now")
                    XCTAssertTrue(pendingEntity?.minedHeight != nil)
                    XCTAssertEqual(pendingEntity?.minedHeight, sentTxHeight)
                    mineExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }

        await fulfillment(of: [mineExpectation, transactionMinedExpectation, foundTransactionsExpectation], timeout: 5)
        
        // 7 advance to confirmation
        let advanceToConfirmation = sentTxHeight + 10

        try coordinator.applyStaged(blockheight: advanceToConfirmation)
        
        sleep(2)
        
        let confirmExpectation = XCTestExpectation(description: "confirm expectation")
        notificationHandler.transactionsFound = { txs in
            XCTFail("We shouldn't find any transactions at this point but found \(txs)")
        }
        notificationHandler.synchronizerMinedTransaction = { transaction in
            XCTFail("We shouldn't find any mined transactions at this point but found \(transaction)")
        }

        do {
            try await coordinator.sync(
                completion: { _ in
                    confirmExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }
        
        await fulfillment(of: [confirmExpectation], timeout: 5)
        
        let confirmedPending = try await coordinator.synchronizer
            .allPendingTransactions()
            .first(where: { $0.rawID == pendingTx.rawID })
        
        XCTAssertNil(confirmedPending, "pending, now confirmed transaction found")

        let expectedVerifiedBalance = try await coordinator.synchronizer.getShieldedVerifiedBalance()
        let expectedBalance = try await coordinator.synchronizer.getShieldedBalance()
        XCTAssertEqual(expectedBalance, Zatoshi(100000))
        XCTAssertEqual(expectedVerifiedBalance, Zatoshi(100000))
    }
    
    /**
    Verify available balance is correct in all wallet states during a send

    This can be either a Wallet test or a Synchronizer test. The latter is supposed to be simpler because it involves no UI testing whatsoever.

    Precondition:
    Account has spendable funds
    Librustzcash is ‘synced’ up to ‘current tip’

    Action:
    Send Amount(*) to zAddr

    Success per state:
    Sent:  (previous available funds - spent note + change) equals to (previous available funds - sent amount)
    Error:  previous available funds  equals to current funds
    */
    // FIXME [#782]: Fix tests
    func disabled_testVerifyAvailableBalanceDuringSend() async throws {
        try FakeChainBuilder.buildChain(darksideWallet: coordinator.service, branchID: branchID, chainName: chainName)
        
        try coordinator.applyStaged(blockheight: defaultLatestHeight)

        sleep(1)
        
        do {
            try await coordinator.sync(
                completion: { _ in
                    self.syncedExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }

        await fulfillment(of: [syncedExpectation], timeout: 60)
        
        let spendingKey = coordinator.spendingKey
        
        let presendVerifiedBalance: Zatoshi = try await coordinator.synchronizer.getShieldedVerifiedBalance()
        
        /*
        there's more zatoshi to send than network fee
        */
        XCTAssertTrue(presendVerifiedBalance >= network.constants.defaultFee(for: defaultLatestHeight) + sendAmount)
        
        var pendingTx: ZcashTransaction.Overview?

        do {
            let transaction = try await coordinator.synchronizer.sendToAddress(
                spendingKey: spendingKey,
                zatoshi: sendAmount,
                toAddress: try Recipient(Environment.testRecipientAddress, network: self.network.networkType),
                memo: try Memo(string: "this is a test")
            )
            pendingTx = transaction
            self.sentTransactionExpectation.fulfill()
        } catch {
            // balance should be the same as before sending if transaction failed
            let expectedVerifiedBalance = try await coordinator.synchronizer.getShieldedVerifiedBalance()
            XCTAssertEqual(expectedVerifiedBalance, presendVerifiedBalance)
            XCTFail("sendToAddress failed: \(error)")
        }

        var expectedVerifiedBalance = try await coordinator.synchronizer.getShieldedVerifiedBalance()
        XCTAssertTrue(expectedVerifiedBalance > .zero)
        await fulfillment(of: [sentTransactionExpectation], timeout: 12)
        
        // sync and mine
        
        guard let rawTx = try coordinator.getIncomingTransactions()?.first else {
            XCTFail("no incoming transaction after")
            return
        }
        
        let latestHeight = try await coordinator.latestHeight()
        let sentTxHeight = latestHeight + 1
        try coordinator.stageBlockCreate(height: sentTxHeight)
        
        try coordinator.stageTransaction(rawTx, at: sentTxHeight)
        try coordinator.applyStaged(blockheight: sentTxHeight)
        sleep(1)
        let mineExpectation = XCTestExpectation(description: "mineTxExpectation")
        
        do {
            try await coordinator.sync(
                completion: { _ in
                    mineExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }

        await fulfillment(of: [mineExpectation], timeout: 5)

        expectedVerifiedBalance = try await coordinator.synchronizer.getShieldedVerifiedBalance()
        let expectedBalance = try await coordinator.synchronizer.getShieldedBalance()

        XCTAssertEqual(
            presendVerifiedBalance - self.sendAmount - network.constants.defaultFee(for: defaultLatestHeight),
            expectedBalance
        )
        
        XCTAssertEqual(
            presendVerifiedBalance - self.sendAmount - network.constants.defaultFee(for: defaultLatestHeight),
            expectedVerifiedBalance
        )
        
        guard let transaction = pendingTx else {
            XCTFail("pending transaction nil")
            return
        }

        /*
        basic health check
        */
        XCTAssertEqual(transaction.value, self.sendAmount)

        let outputs = await coordinator.synchronizer.getTransactionOutputs(for: transaction)

        guard outputs.count == 2 else {
            XCTFail("Expected sent transaction to have 2 outputs")
            return
        }

        guard let changeOutput = outputs.first(where: { $0.isChange }) else {
            XCTFail("Sent transaction has no change")
            return
        }

        guard let sentOutput = outputs.first(where: { !$0.isChange }) else {
            XCTFail("sent transaction does not have a 'sent' output")
            return
        }

        //  (previous available funds - spent note + change) equals to (previous available funds - sent amount)
        self.verifiedBalanceValidation(
            previousBalance: presendVerifiedBalance,
            spentNoteValue: sentOutput.value,
            changeValue: changeOutput.value,
            sentAmount: self.sendAmount,
            currentVerifiedBalance: try await coordinator.synchronizer.getShieldedVerifiedBalance()
        )
    }
    
    /**
    Verify total balance in all wallet states during a send
    This can be either a Wallet test or a Synchronizer test. The latter is supposed to be simpler because it involves no UI testing whatsoever.

    Precondition:
    Account has spendable funds
    Librustzcash is ‘synced’ up to ‘current tip’

    Action:
    Send Amount to zAddr

    Success per state:
    Sent:  (total balance funds - sentAmount) equals to (previous available funds - sent amount)
    Error:  previous total balance  funds  equals to current total balance

    */
    // FIXME [#787]: Fix test
    func disabled_testVerifyTotalBalanceDuringSend() async throws {
        try FakeChainBuilder.buildChain(darksideWallet: coordinator.service, branchID: branchID, chainName: chainName)
        
        try coordinator.applyStaged(blockheight: defaultLatestHeight)
        
        sleep(2)
        do {
            try await coordinator.sync(
                completion: { _ in
                    self.syncedExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }
        
        await fulfillment(of: [syncedExpectation], timeout: 5)
        
        let spendingKey = coordinator.spendingKey

        let presendBalance: Zatoshi = try await coordinator.synchronizer.getShieldedBalance()

        // there's more zatoshi to send than network fee
        XCTAssertTrue(presendBalance >= network.constants.defaultFee(for: defaultLatestHeight) + sendAmount)
        var pendingTx: ZcashTransaction.Overview?
        
        var testError: Error?
        do {
            let transaction = try await coordinator.synchronizer.sendToAddress(
                spendingKey: spendingKey,
                zatoshi: sendAmount,
                toAddress: try Recipient(Environment.testRecipientAddress, network: self.network.networkType),
                memo: try Memo(string: "test send \(self.description) \(Date().description)")
            )
            pendingTx = transaction
            self.sentTransactionExpectation.fulfill()
        } catch {
            // balance should be the same as before sending if transaction failed
            testError = error
            XCTFail("sendToAddress failed: \(error)")
        }

        var expectedVerifiedBalance = try await coordinator.synchronizer.getShieldedVerifiedBalance()
        XCTAssertTrue(expectedVerifiedBalance > .zero)
        await fulfillment(of: [sentTransactionExpectation], timeout: 12)

        expectedVerifiedBalance = try await coordinator.synchronizer.getShieldedVerifiedBalance()
        if let testError {
            XCTAssertEqual(expectedVerifiedBalance, presendBalance)
            XCTFail("error: \(testError)")
            return
        }
        guard let transaction = pendingTx else {
            XCTFail("pending transaction nil after send")
            return
        }
        
        XCTAssertEqual(transaction.value, self.sendAmount)

        var expectedBalance = try await coordinator.synchronizer.getShieldedBalance()
        XCTAssertEqual(
            expectedBalance,
            presendBalance - self.sendAmount - network.constants.defaultFee(for: defaultLatestHeight)
        )
        
        let latestHeight = try await coordinator.latestHeight()
        let sentTxHeight = latestHeight + 1
        try coordinator.stageBlockCreate(height: sentTxHeight)
        guard let rawTx = try coordinator.getIncomingTransactions()?.first else {
            XCTFail("no incoming transaction after send")
            return
        }
        
        try coordinator.stageTransaction(rawTx, at: latestHeight + 1)
        try coordinator.applyStaged(blockheight: latestHeight + 1)
        sleep(2)
        let mineExpectation = XCTestExpectation(description: "mineTxExpectation")
        
        do {
            try await coordinator.sync(
                completion: { _ in
                    mineExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }

        await fulfillment(of: [mineExpectation], timeout: 5)

        expectedBalance = try await coordinator.synchronizer.getShieldedBalance()
        XCTAssertEqual(
            presendBalance - self.sendAmount - network.constants.defaultFee(for: defaultLatestHeight),
            expectedBalance
        )
    }
    
    /**
    Verify incoming transactions
    This can be either a Wallet test or a Synchronizer test. The latter is supposed to be simpler because it involves no UI testing whatsoever.
     
    Precondition:
    Librustzcash is ‘synced’ up to ‘current tip’
    Known list of expected transactions on the block range to sync the wallet up to.
    Known expected balance on the block range to sync the wallet up to.
    Action:
    sync to latest height
    Success criteria:
    The transaction list matches the expected one
    Balance matches expected balance

    */
    func testVerifyIncomingTransaction() async throws {
        try FakeChainBuilder.buildChain(darksideWallet: coordinator.service, branchID: branchID, chainName: chainName)
        try coordinator.applyStaged(blockheight: defaultLatestHeight)
        sleep(1)

        try await coordinator.sync(
            completion: { _ in
                self.syncedExpectation.fulfill()
            },
            error: self.handleError
        )
        
        await fulfillment(of: [syncedExpectation], timeout: 5)

        let clearedTransactions = await coordinator.synchronizer.transactions
        let expectedBalance = try await coordinator.synchronizer.getShieldedBalance()
        XCTAssertEqual(clearedTransactions.count, 2)
        XCTAssertEqual(expectedBalance, Zatoshi(200000))
    }
    
    /**
    Verify change transactions

    This can be either a Wallet test or a Synchronizer test. The latter is supposed to be simpler because it involves no UI testing whatsoever.

    Precondition
    Librustzcash is ‘synced’ up to ‘current tip’
    Known list of expected transactions on the block range to sync the wallet up to.
    Known expected balance on the block range to sync the wallet up to.
    There’s a spendable note with value > send amount that generates change

    Action:
    Send amount to zAddr
    sync to minedHeight + 1

    Success Criteria:
    There’s a sent transaction matching the amount sent to the given zAddr
    minedHeight is not -1
    Balance meets verified Balance and total balance criteria
    There’s a change note of value (previous note value - sent amount)

    */
    // FIXME [#786]: Fix test
    func disabled_testVerifyChangeTransaction() async throws {
        try FakeChainBuilder.buildSingleNoteChain(darksideWallet: coordinator.service, branchID: branchID, chainName: chainName)
        
        try coordinator.applyStaged(blockheight: defaultLatestHeight)
        sleep(1)
        let sendExpectation = XCTestExpectation(description: "send expectation")
        let createToAddressExpectation = XCTestExpectation(description: "create to address")
        
        try coordinator.setLatestHeight(height: defaultLatestHeight)

        /*
        sync to current tip
        */
        do {
            try await coordinator.sync(
                completion: { _ in
                    self.syncedExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }

        await fulfillment(of: [syncedExpectation], timeout: 6)
        
        let previousVerifiedBalance: Zatoshi = try await coordinator.synchronizer.getShieldedVerifiedBalance()
        let previousTotalBalance: Zatoshi = try await coordinator.synchronizer.getShieldedBalance()
        
        let spendingKey = coordinator.spendingKey
        
        /*
        Send
        */
        let memo = try Memo(string: "shielding is fun!")
        var pendingTx: ZcashTransaction.Overview?

        do {
            let transaction = try await coordinator.synchronizer.sendToAddress(
                spendingKey: spendingKey,
                zatoshi: sendAmount,
                toAddress: try Recipient(Environment.testRecipientAddress, network: self.network.networkType),
                memo: memo
            )
            pendingTx = transaction
            sendExpectation.fulfill()
        } catch {
            XCTFail("error sending \(error)")
        }
        await fulfillment(of: [createToAddressExpectation], timeout: 30)
        
        let syncToMinedheightExpectation = XCTestExpectation(description: "sync to mined height + 1")
        
        /*
        include sent transaction in block
        */
        guard let rawTx = try coordinator.getIncomingTransactions()?.first else {
            XCTFail("pending transaction nil after send")
            return
        }
        
        let latestHeight = try await coordinator.latestHeight()
        let sentTxHeight = latestHeight + 1
        try coordinator.stageBlockCreate(height: sentTxHeight, count: 12)
        try coordinator.stageTransaction(rawTx, at: sentTxHeight)
        try coordinator.applyStaged(blockheight: sentTxHeight + 11  )
        sleep(2)
        
        /*
        Sync to that block
        */
        do {
            try await coordinator.sync(
                completion: { synchronizer in
                    let confirmedTx: ZcashTransaction.Overview!
                    do {
                        confirmedTx = try await synchronizer.allTransactions().first(where: { confirmed -> Bool in
                            confirmed.rawID == pendingTx?.rawID
                        })
                    } catch {
                        XCTFail("Error  retrieving cleared transactions")
                        return
                    }

                    /*
                    There’s a sent transaction matching the amount sent to the given zAddr
                    */
                    XCTAssertEqual(confirmedTx.value, self.sendAmount)
                    // TODO [#683]: Add API to SDK to fetch memos.
                    //                    let confirmedMemo = try confirmedTx.memo?.intoMemoBytes()?.intoMemo()
                    //                    XCTAssertEqual(confirmedMemo, memo)

                    /*
                    Find out what note was used
                    */

                    let outputs = await self.coordinator.synchronizer.getTransactionOutputs(for: confirmedTx)

                    guard outputs.count == 2 else {
                        XCTFail("Expected sent transaction to have 2 outputs")
                        return
                    }

                    guard let changeOutput = outputs.first(where: { $0.isChange }) else {
                        XCTFail("Sent transaction has no change")
                        return
                    }

                    guard let sentOutput = outputs.first(where: { !$0.isChange }) else {
                        XCTFail("sent transaction does not have a 'sent' output")
                        return
                    }

                    /*
                    There’s a change note of value (previous note value - sent amount)
                    */
                    XCTAssertEqual(
                        previousVerifiedBalance - self.sendAmount - self.network.constants.defaultFee(for: self.defaultLatestHeight),
                        changeOutput.value
                    )

                    /*
                    Balance meets verified Balance and total balance criteria
                    */
                    self.verifiedBalanceValidation(
                        previousBalance: previousVerifiedBalance,
                        spentNoteValue: sentOutput.value,
                        changeValue: changeOutput.value,
                        sentAmount: self.sendAmount,
                        currentVerifiedBalance: try await synchronizer.getShieldedVerifiedBalance()
                    )

                    self.totalBalanceValidation(
                        totalBalance: try await synchronizer.getShieldedBalance(),
                        previousTotalbalance: previousTotalBalance,
                        sentAmount: self.sendAmount
                    )

                    syncToMinedheightExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }
        
        await fulfillment(of: [syncToMinedheightExpectation], timeout: 5)
    }
    
    /**
    Verify transactions that expire are reflected accurately in balance
    This test requires the transaction to expire.

    How can we mock or cause this? Would createToAddress and faking a network submission through lightwalletService and syncing 10 more blocks work?
     
    Precondition:
    Account has spendable funds
    Librustzcash is ‘synced’ up to ‘current tip’ †
    Current tip can be scanned 10 blocks past the generated to be expired transaction

    Action:
    Sync to current tip
    Create transaction to zAddr
    Mock send success
    Sync 10 blocks more

    Success Criteria:
    There’s a pending transaction that has expired
    Total Balance is equal to total balance previously shown before sending the expired transaction
    Verified Balance is equal to verified balance previously shown before sending the expired transaction
    */
    func testVerifyBalanceAfterExpiredTransaction() async throws {
        try FakeChainBuilder.buildChain(darksideWallet: coordinator.service, branchID: branchID, chainName: chainName)
        
        try coordinator.applyStaged(blockheight: self.defaultLatestHeight + 10)
        sleep(2)

        do {
            try await coordinator.sync(
                completion: { _ in
                    self.syncedExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }

        await fulfillment(of: [syncedExpectation], timeout: 5)
        
        let spendingKey = coordinator.spendingKey
        
        let previousVerifiedBalance: Zatoshi = try await coordinator.synchronizer.getShieldedVerifiedBalance()
        let previousTotalBalance: Zatoshi = try await coordinator.synchronizer.getShieldedBalance()
        let sendExpectation = XCTestExpectation(description: "send expectation")
        var pendingTx: ZcashTransaction.Overview?
        do {
            let pending = try await coordinator.synchronizer.sendToAddress(
                spendingKey: spendingKey,
                zatoshi: sendAmount,
                toAddress: try Recipient(Environment.testRecipientAddress, network: self.network.networkType),
                memo: try Memo(string: "test send \(self.description)")
            )
            pendingTx = pending
            sendExpectation.fulfill()
        } catch {
            // balance should be the same as before sending if transaction failed
            let expectedVerifiedBalance = try await coordinator.synchronizer.getShieldedVerifiedBalance()
            let expectedBalance = try await coordinator.synchronizer.getShieldedBalance()
            XCTAssertEqual(expectedVerifiedBalance, previousVerifiedBalance)
            XCTAssertEqual(expectedBalance, previousTotalBalance)
            XCTFail("sendToAddress failed: \(error)")
        }

        await fulfillment(of: [sendExpectation], timeout: 12)
        
        guard let pendingTransaction = pendingTx, let expiryHeight = pendingTransaction.expiryHeight, expiryHeight > defaultLatestHeight else {
            XCTFail("No pending transaction")
            return
        }
        
        let expirationSyncExpectation = XCTestExpectation(description: "expiration sync expectation")

        try coordinator.applyStaged(blockheight: expiryHeight + 1)
        
        sleep(2)
        
        do {
            try await coordinator.sync(
                completion: { _ in
                    expirationSyncExpectation.fulfill()
                },
                error: self.handleError
            )
        } catch {
            handleError(error)
        }

        await fulfillment(of: [expirationSyncExpectation], timeout: 5)

        let expectedVerifiedBalance = try await coordinator.synchronizer.getShieldedVerifiedBalance()
        let expectedBalance = try await coordinator.synchronizer.getShieldedBalance()
        /*
        Verified Balance is equal to verified balance previously shown before sending the expired transaction
        */
        XCTAssertEqual(expectedVerifiedBalance, previousVerifiedBalance)
        
        /*
        Total Balance is equal to total balance previously shown before sending the expired transaction
        */
        XCTAssertEqual(expectedBalance, previousTotalBalance)

        let transactionRepo = TransactionSQLDAO(
            dbProvider: SimpleConnectionProvider(
                path: coordinator.synchronizer.initializer.dataDbURL.absoluteString
            )
        )

        let expiredPending = try await transactionRepo.find(id: pendingTransaction.id)
        
        /*
        there no sent transaction displayed
        */

        let sentTransactions = try await coordinator.synchronizer.allSentTransactions()
        XCTAssertNil(sentTransactions.first(where: { $0.id == pendingTransaction.id }))
        /*
        There’s a pending transaction that has expired
        */
        XCTAssertNil(expiredPending.minedHeight)
    }
    
    func handleError(_ error: Error?) {
        guard let testError = error else {
            XCTFail("failed with nil error")
            return
        }
        XCTFail("Failed with error: \(testError)")
    }
    
    /**
    check if (previous available funds - spent note + change) equals to (previous available funds - sent amount)
    */
    func verifiedBalanceValidation(
        previousBalance: Zatoshi,
        spentNoteValue: Zatoshi,
        changeValue: Zatoshi,
        sentAmount: Zatoshi,
        currentVerifiedBalance: Zatoshi
    ) {
        XCTAssertEqual(previousBalance - spentNoteValue + changeValue, currentVerifiedBalance - sentAmount)
    }
    
    func totalBalanceValidation(
        totalBalance: Zatoshi,
        previousTotalbalance: Zatoshi,
        sentAmount: Zatoshi
    ) {
        XCTAssertEqual(totalBalance, previousTotalbalance - sentAmount - network.constants.defaultFee(for: defaultLatestHeight))
    }
}

class SDKSynchonizerListener {
    var transactionsFound: (([ZcashTransaction.Overview]) -> Void)?
    var synchronizerMinedTransaction: ((ZcashTransaction.Overview) -> Void)?
    var cancellables: [AnyCancellable] = []
    
    func subscribeToSynchronizer(_ synchronizer: SDKSynchronizer) {
        synchronizer.eventStream
            .sink(
                receiveValue: { [weak self] event in
                    switch event {
                    case let .minedTransaction(transaction):
                        self?.txMined(transaction)

                    case let .foundTransactions(transactions, _):
                        self?.txFound(transactions)

                    case .storedUTXOs, .connectionStateChanged:
                        break
                    }
                }
            )
            .store(in: &cancellables)
    }
    
    func unsubscribe() {
        cancellables = []
    }
    
    func txFound(_ txs: [ZcashTransaction.Overview]) {
        DispatchQueue.main.async { [weak self] in
            self?.transactionsFound?(txs)
        }
    }
    
    func txMined(_ transaction: ZcashTransaction.Overview) {
        DispatchQueue.main.async { [weak self] in
            self?.synchronizerMinedTransaction?(transaction)
        }
    }
}