nim-chronos/tests/testfut.nim

#                Chronos Test Suite
#            (c) Copyright 2018-Present
#         Status Research & Development GmbH
#
#              Licensed under either of
#  Apache License, version 2.0, (LICENSE-APACHEv2)
#              MIT license (LICENSE-MIT)
import unittest2
import stew/results
import ../chronos, ../chronos/unittest2/asynctests

{.used.}

type
  TestFooConnection* = ref object
    id*: int

suite "Future[T] behavior test suite":
  proc testFuture1(): Future[int] {.async.} =
    await sleepAsync(0.milliseconds)

  proc testFuture2(): Future[int] {.async.} =
    return 1

  proc testFuture3(): Future[int] {.async.} =
    result = await testFuture2()

  proc testFuture100(): Future[int] {.async.} =
    await sleepAsync(100.milliseconds)

  test "Async undefined behavior (#7758) test":
    var fut = testFuture1()
    poll()
    poll()
    if not fut.finished:
      poll()
    check: fut.finished

  test "Immediately completed asynchronous procedure test":
    var fut = testFuture3()
    check: fut.finished

  test "Future[T] callbacks are invoked in reverse order (#7197) test":
    var testResult = ""
    var fut = testFuture1()
    fut.addCallback proc(udata: pointer) =
      testResult &= "1"
    fut.addCallback proc(udata: pointer) =
      testResult &= "2"
    fut.addCallback proc(udata: pointer) =
      testResult &= "3"
    fut.addCallback proc(udata: pointer) =
      testResult &= "4"
    fut.addCallback proc(udata: pointer) =
      testResult &= "5"
    discard waitFor(fut)

    check:
      fut.finished
      testResult == "12345"

  test "Future[T] callbacks not changing order after removeCallback()":
    var testResult = ""
    var fut = testFuture1()
    proc cb1(udata: pointer) =
      testResult &= "1"
    proc cb2(udata: pointer) =
      testResult &= "2"
    proc cb3(udata: pointer) =
      testResult &= "3"
    proc cb4(udata: pointer) =
      testResult &= "4"
    proc cb5(udata: pointer) =
      testResult &= "5"
    fut.addCallback cb1
    fut.addCallback cb2
    fut.addCallback cb3
    fut.addCallback cb4
    fut.addCallback cb5
    fut.removeCallback cb3
    discard waitFor(fut)
    check:
      fut.finished
      testResult == "1245"

  asyncTest "wait[T]() test":
    block:
      ## Test for not immediately completed future and timeout = -1
      let res =
        try:
          discard await wait(testFuture1(), InfiniteDuration)
          true
        except CatchableError:
          false
      check res
    block:
      ## Test for immediately completed future and timeout = -1
      let res =
        try:
          discard await wait(testFuture2(), InfiniteDuration)
          true
        except CatchableError:
          false
      check res
    block:
      ## Test for not immediately completed future and timeout = 0
      let res =
        try:
          discard await wait(testFuture1(), 0.milliseconds)
          false
        except AsyncTimeoutError:
          true
        except CatchableError:
          false
      check res

    block:
      ## Test for immediately completed future and timeout = 0
      let res =
        try:
          discard await wait(testFuture2(), 0.milliseconds)
          true
        except CatchableError:
          false
      check res

    block:
      ## Test for future which cannot be completed in timeout period
      let res =
        try:
          discard await wait(testFuture100(), 50.milliseconds)
          false
        except AsyncTimeoutError:
          true
        except CatchableError:
          false
      check res

    block:
      ## Test for future which will be completed before timeout exceeded.
      let res =
        try:
          discard await wait(testFuture100(), 500.milliseconds)
          true
        except CatchableError:
          false
      check res

  asyncTest "Discarded result Future[T] test":
    var completedFutures = 0

    proc client1() {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)

    proc client2() {.async.} =
      await sleepAsync(200.milliseconds)
      inc(completedFutures)

    proc client3() {.async.} =
      await sleepAsync(300.milliseconds)
      inc(completedFutures)

    proc client4() {.async.} =
      await sleepAsync(400.milliseconds)
      inc(completedFutures)

    proc client5() {.async.} =
      await sleepAsync(500.milliseconds)
      inc(completedFutures)

    proc client1f() {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc client2f() {.async.} =
      await sleepAsync(200.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc client3f() {.async.} =
      await sleepAsync(300.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc client4f() {.async.} =
      await sleepAsync(400.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc client5f() {.async.} =
      await sleepAsync(500.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    discard client1()
    discard client1f()
    discard client2()
    discard client2f()
    discard client3()
    discard client3f()
    discard client4()
    discard client4f()
    discard client5()
    discard client5f()

    await sleepAsync(1.seconds)
    check completedFutures == 10

  test "allFutures(zero) test":
    var tseq = newSeq[Future[int]]()
    var fut = allFutures(tseq)
    check:
      fut.finished

  asyncTest "allFutures(varargs) test":
    var completedFutures = 0

    proc vlient1() {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)

    proc vlient2() {.async.} =
      await sleepAsync(200.milliseconds)
      inc(completedFutures)

    proc vlient3() {.async.} =
      await sleepAsync(300.milliseconds)
      inc(completedFutures)

    proc vlient4() {.async.} =
      await sleepAsync(400.milliseconds)
      inc(completedFutures)

    proc vlient5() {.async.} =
      await sleepAsync(500.milliseconds)
      inc(completedFutures)

    proc vlient1f() {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc vlient2f() {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc vlient3f() {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc vlient4f() {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc vlient5f() {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc client1(): Future[int] {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)
      result = 1

    proc client2(): Future[int] {.async.} =
      await sleepAsync(200.milliseconds)
      inc(completedFutures)
      result = 1

    proc client3(): Future[int] {.async.} =
      await sleepAsync(300.milliseconds)
      inc(completedFutures)
      result = 1

    proc client4(): Future[int] {.async.} =
      await sleepAsync(400.milliseconds)
      inc(completedFutures)
      result = 1

    proc client5(): Future[int] {.async.} =
      await sleepAsync(500.milliseconds)
      inc(completedFutures)
      result = 1

    proc client1f(): Future[int] {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc client2f(): Future[int] {.async.} =
      await sleepAsync(200.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc client3f(): Future[int] {.async.} =
      await sleepAsync(300.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc client4f(): Future[int] {.async.} =
      await sleepAsync(400.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc client5f(): Future[int] {.async.} =
      await sleepAsync(500.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    await allFutures(vlient1(), vlient2(), vlient3(), vlient4(), vlient5())
    check completedFutures == 5

    completedFutures = 0

    await allFutures(vlient1(), vlient1f(), vlient2(), vlient2f(), vlient3(),
                     vlient3f(), vlient4(), vlient4f(), vlient5(), vlient5f())
    check completedFutures == 10

    completedFutures = 0

    await allFutures(client1(), client2(), client3(), client4(), client5())
    check completedFutures == 5

    completedFutures = 0

    await allFutures(client1(), client1f(), client2(), client2f(), client3(),
                     client3f(), client4(), client4f(), client5(), client5f())
    check completedFutures == 10

  asyncTest "allFutures(varargs) test":
    var completedFutures = 0
    var vfutures = newSeq[Future[void]]()
    var nfutures = newSeq[Future[int]]()

    proc vlient1() {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)

    proc vlient2() {.async.} =
      await sleepAsync(200.milliseconds)
      inc(completedFutures)

    proc vlient3() {.async.} =
      await sleepAsync(300.milliseconds)
      inc(completedFutures)

    proc vlient4() {.async.} =
      await sleepAsync(400.milliseconds)
      inc(completedFutures)

    proc vlient5() {.async.} =
      await sleepAsync(500.milliseconds)
      inc(completedFutures)

    proc vlient1f() {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc vlient2f() {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc vlient3f() {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc vlient4f() {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc vlient5f() {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc client1(): Future[int] {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)
      result = 1

    proc client2(): Future[int] {.async.} =
      await sleepAsync(200.milliseconds)
      inc(completedFutures)
      result = 1

    proc client3(): Future[int] {.async.} =
      await sleepAsync(300.milliseconds)
      inc(completedFutures)
      result = 1

    proc client4(): Future[int] {.async.} =
      await sleepAsync(400.milliseconds)
      inc(completedFutures)
      result = 1

    proc client5(): Future[int] {.async.} =
      await sleepAsync(500.milliseconds)
      inc(completedFutures)
      result = 1

    proc client1f(): Future[int] {.async.} =
      await sleepAsync(100.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc client2f(): Future[int] {.async.} =
      await sleepAsync(200.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc client3f(): Future[int] {.async.} =
      await sleepAsync(300.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc client4f(): Future[int] {.async.} =
      await sleepAsync(400.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    proc client5f(): Future[int] {.async.} =
      await sleepAsync(500.milliseconds)
      inc(completedFutures)
      if true:
        raise newException(ValueError, "")

    vfutures.setLen(0)
    for i in 0..<10:
      vfutures.add(vlient1())
      vfutures.add(vlient2())
      vfutures.add(vlient3())
      vfutures.add(vlient4())
      vfutures.add(vlient5())

    await allFutures(vfutures)
    # 5 * 10 completed futures = 50
    check completedFutures == 50

    completedFutures = 0
    vfutures.setLen(0)
    for i in 0..<10:
      vfutures.add(vlient1())
      vfutures.add(vlient1f())
      vfutures.add(vlient2())
      vfutures.add(vlient2f())
      vfutures.add(vlient3())
      vfutures.add(vlient3f())
      vfutures.add(vlient4())
      vfutures.add(vlient4f())
      vfutures.add(vlient5())
      vfutures.add(vlient5f())

    await allFutures(vfutures)
    # 10 * 10 completed futures = 100
    check completedFutures == 100

    completedFutures = 0
    nfutures.setLen(0)
    for i in 0..<10:
      nfutures.add(client1())
      nfutures.add(client2())
      nfutures.add(client3())
      nfutures.add(client4())
      nfutures.add(client5())

    await allFutures(nfutures)
    # 5 * 10 completed futures = 50
    check completedFutures == 50

    completedFutures = 0
    nfutures.setLen(0)
    for i in 0..<10:
      nfutures.add(client1())
      nfutures.add(client1f())
      nfutures.add(client2())
      nfutures.add(client2f())
      nfutures.add(client3())
      nfutures.add(client3f())
      nfutures.add(client4())
      nfutures.add(client4f())
      nfutures.add(client5())
      nfutures.add(client5f())

    await allFutures(nfutures)

    # 10 * 10 completed futures = 100
    check completedFutures == 100

  test "allFutures() already completed test":
    proc client1(): Future[int] {.async.} =
      result = 1

    proc client2(): Future[int] {.async.} =
      if true:
        raise newException(ValueError, "")

    var fut = allFutures(client1(), client2())
    check:
      fut.finished()
      not(fut.failed())

  test "allFinished() already completed test":
    proc client1(): Future[int] {.async.} =
      result = 1

    proc client2(): Future[int] {.async.} =
      if true:
        raise newException(ValueError, "")

    var fut = allFinished(client1(), client2())
    check:
      fut.finished()
      not(fut.failed())
      len(fut.read()) == 2

  test "one(zero) test":
    var tseq = newSeq[Future[int]]()
    var fut = one(tseq)
    check: fut.finished and fut.failed

  asyncTest "one(varargs) test":
    proc vlient1() {.async.} =
      await sleepAsync(100.milliseconds)

    proc vlient2() {.async.} =
      await sleepAsync(200.milliseconds)

    proc vlient3() {.async.} =
      await sleepAsync(300.milliseconds)

    proc client1(): Future[int] {.async.} =
      await sleepAsync(100.milliseconds)
      result = 10

    proc client2(): Future[int] {.async.} =
      await sleepAsync(200.milliseconds)
      result = 20

    proc client3(): Future[int] {.async.} =
      await sleepAsync(300.milliseconds)
      result = 30

    var fut11 = vlient1()
    var fut12 = vlient2()
    var fut13 = vlient3()
    var res1 = await one(fut11, fut12, fut13)

    var fut21 = vlient2()
    var fut22 = vlient1()
    var fut23 = vlient3()
    var res2 = await one(fut21, fut22, fut23)

    var fut31 = vlient3()
    var fut32 = vlient2()
    var fut33 = vlient1()
    var res3 = await one(fut31, fut32, fut33)

    check:
      fut11 == res1
      fut22 == res2
      fut33 == res3

    var cut11 = client1()
    var cut12 = client2()
    var cut13 = client3()
    var res4 = await one(cut11, cut12, cut13)

    var cut21 = client2()
    var cut22 = client1()
    var cut23 = client3()
    var res5 = await one(cut21, cut22, cut23)

    var cut31 = client3()
    var cut32 = client2()
    var cut33 = client1()
    var res6 = await one(cut31, cut32, cut33)

    check:
      cut11 == res4
      cut22 == res5
      cut33 == res6

  asyncTest "one(seq) test":
    proc vlient1() {.async.} =
      await sleepAsync(100.milliseconds)

    proc vlient2() {.async.} =
      await sleepAsync(200.milliseconds)

    proc vlient3() {.async.} =
      await sleepAsync(300.milliseconds)

    proc client1(): Future[int] {.async.} =
      await sleepAsync(100.milliseconds)
      result = 10

    proc client2(): Future[int] {.async.} =
      await sleepAsync(200.milliseconds)
      result = 20

    proc client3(): Future[int] {.async.} =
      await sleepAsync(300.milliseconds)
      result = 30

    var v10 = vlient1()
    var v11 = vlient2()
    var v12 = vlient3()
    var res1 = await one(@[v10, v11, v12])

    var v20 = vlient2()
    var v21 = vlient1()
    var v22 = vlient3()
    var res2 = await one(@[v20, v21, v22])

    var v30 = vlient3()
    var v31 = vlient2()
    var v32 = vlient1()
    var res3 = await one(@[v30, v31, v32])

    check:
      res1 == v10
      res2 == v21
      res3 == v32

    var c10 = client1()
    var c11 = client2()
    var c12 = client3()
    var res4 = await one(@[c10, c11, c12])

    var c20 = client2()
    var c21 = client1()
    var c22 = client3()
    var res5 = await one(@[c20, c21, c22])

    var c30 = client3()
    var c31 = client2()
    var c32 = client1()
    var res6 = await one(@[c30, c31, c32])

    check:
      res4 == c10
      res5 == c21
      res6 == c32

  test "one(completed) test":
    proc client1(): Future[int] {.async.} =
      result = 1

    proc client2(): Future[int] {.async.} =
      if true:
        raise newException(ValueError, "")

    proc client3(): Future[int] {.async.} =
      await sleepAsync(100.milliseconds)
      result = 3

    var f10 = client1()
    var f20 = client2()
    var f30 = client3()
    var fut1 = one(f30, f10, f20)
    var f11 = client1()
    var f21 = client2()
    var f31 = client3()
    var fut2 = one(f31, f21, f11)

    check:
      fut1.finished()
      not(fut1.failed())
      fut1.read() == f10
      fut2.finished()
      not(fut2.failed())
      fut2.read() == f21

  asyncTest "or() test":
    proc client1() {.async.} =
      await sleepAsync(200.milliseconds)

    proc client2() {.async.} =
      await sleepAsync(300.milliseconds)

    proc client3() {.async.} =
      await sleepAsync(100.milliseconds)
      if true:
        raise newException(ValueError, "")

    proc client4() {.async.} =
      await sleepAsync(400.milliseconds)
      if true:
        raise newException(IOError, "")

    proc client5() {.async.} =
      discard

    proc client6() {.async.} =
      if true:
        raise newException(ValueError, "")

    proc client7() {.async.} =
      if true:
        raise newException(IOError, "")

    block:
      let res =
        try:
          await client1() or client2()
          true
        except CatchableError:
          false
      check res

    block:
      let res =
        try:
          await client2() or client1()
          true
        except CatchableError:
          false
      check res

    block:
      let res =
        try:
          await client1() or client4()
          true
        except IOError:
          false
        except CatchableError:
          false
      check res

    block:
      let res =
        try:
          await client2() or client4()
          true
        except IOError:
          false
        except CatchableError:
          false
      check res

    block:
      let res =
        try:
          await client4() or client2()
          true
        except IOError:
          false
        except CatchableError:
          false
      check res

    block:
      let res =
        try:
          await client1() or client3()
          false
        except ValueError:
          true
        except CatchableError:
          false
      check res

    block:
      let res =
        try:
          await client3() or client1()
          false
        except ValueError:
          true
        except CatchableError:
          false
      check res

    block:
      let res =
        try:
          await client3() or client4()
          false
        except ValueError:
          true
        except CatchableError:
          false
      check res

    block:
      let res =
        try:
          await client4() or client3()
          false
        except ValueError:
          true
        except CatchableError:
          false
      check res

    block:
      let res =
        try:
          await client5() or client6()
          true
        except ValueError:
          false
        except CatchableError:
          false
      check res

    block:
      let res =
        try:
          await client6() or client5()
          false
        except ValueError:
          true
        except CatchableError:
          false
      check res

    block:
      let res =
        try:
          await client6() or client7()
          false
        except ValueError:
          true
        except IOError:
          false
        except CatchableError:
          false
      check res

    block:
      let res =
        try:
          await client7() or client6()
          false
        except ValueError:
          false
        except IOError:
          true
        except CatchableError:
          false
      check res

  asyncTest "or() already completed test":
    proc client1(): Future[int] {.async.} =
      result = 1
    proc client2(): Future[int] {.async.} =
      if true:
        raise newException(ValueError, "")
    proc client3(): Future[int] {.async.} =
      await sleepAsync(100.milliseconds)
      result = 3

    block:
      let res =
        try:
          await client1() or client2()
          true
        except ValueError:
          false
        except CatchableError:
          false
      check res

    block:
      var fut1 = client1()
      var fut2 = client3()
      let res =
        try:
          await fut1 or fut2
          true
        except ValueError:
          false
        except CatchableError:
          false
      let discarded {.used.} = await fut2
      check res

    block:
      var fut1 = client2()
      var fut2 = client3()
      let res =
        try:
          await fut1 or fut2
          false
        except ValueError:
          true
        except CatchableError:
          false
      let discarded {.used.} = await fut2
      check res

    block:
      let res =
        try:
          await client2() or client1()
          false
        except ValueError:
          true
        except CatchableError:
          false
      check res

    block:
      var fut1 = client3()
      var fut2 = client1()
      let res =
        try:
          await fut1 or fut2
          true
        except ValueError:
          false
        except CatchableError:
          false
      let discarded {.used.} = await fut1
      check res

    block:
      var fut1 = client3()
      var fut2 = client2()
      let res =
        try:
          await fut1 or fut2
          false
        except ValueError:
          true
        except CatchableError:
          false
      let discarded {.used.} = await fut1
      check res

  asyncTest "tryCancel() async procedure test":
    var completed = 0

    proc client1() {.async.} =
      await sleepAsync(1.seconds)
      inc(completed)

    proc client2() {.async.} =
      await client1()
      inc(completed)

    proc client3() {.async.} =
      await client2()
      inc(completed)

    proc client4() {.async.} =
      await client3()
      inc(completed)

    var fut = client4()
    discard fut.tryCancel()

    # Future must not be cancelled immediately, because it has many nested
    # futures.
    check:
      not fut.cancelled()

    expect(CancelledError):
      await fut

    check completed == 0

  asyncTest "cancelAndWait() test":
    var completed = 0

    proc client1() {.async.} =
      await sleepAsync(1.seconds)
      inc(completed)

    proc client2() {.async.} =
      await client1()
      inc(completed)

    proc client3() {.async.} =
      await client2()
      inc(completed)

    proc client4() {.async.} =
      await client3()
      inc(completed)

    var fut = client4()
    await cancelAndWait(fut)
    check fut.cancelled()

  asyncTest "Break cancellation propagation test":
    var completed = 0

    proc client1() {.async.} =
      await sleepAsync(1.seconds)
      inc(completed)

    proc client2() {.async.} =
      try:
        await client1()
      except CancelledError:
        discard
      inc(completed)

    var fut1 = client2()
    var fut2 = client2()
    discard fut1.tryCancel()
    await fut1
    await cancelAndWait(fut2)
    check:
      not fut1.cancelled()
      not fut2.cancelled()
      completed == 2

  asyncTest "Cancellation callback test":
    var completed = 0
    var cancelled = 0

    proc client1(duration: Duration): Future[void] =
      ## Suspends the execution of the current async procedure for the next
      ## ``duration`` time.
      var retFuture = newFuture[void]()
      let moment = Moment.fromNow(duration)

      proc completion(data: pointer) {.gcsafe.} =
        inc(completed)
        if not(retFuture.finished()):
          retFuture.complete()

      proc cancellation(udata: pointer) {.gcsafe.} =
        inc(cancelled)
        if not(retFuture.finished()):
          removeTimer(moment, completion, cast[pointer](retFuture))

      retFuture.cancelCallback = cancellation
      discard setTimer(moment, completion, cast[pointer](retFuture))
      return retFuture

    var fut = client1(100.milliseconds)
    discard fut.tryCancel()
    await sleepAsync(500.milliseconds)
    check:
      fut.cancelled()
      completed == 0
      cancelled == 1

  asyncTest "Cancellation wait() test":
    var neverFlag1, neverFlag2, neverFlag3: bool
    var waitProc1, waitProc2: bool
    proc neverEndingProc(): Future[void] =
      var res = newFuture[void]()
      proc continuation(udata: pointer) {.gcsafe.} =
        neverFlag2 = true
      proc cancellation(udata: pointer) {.gcsafe.} =
        neverFlag3 = true
      res.addCallback(continuation)
      res.cancelCallback = cancellation
      result = res
      neverFlag1 = true

    proc waitProc() {.async.} =
      try:
        await wait(neverEndingProc(), 100.milliseconds)
      except CancelledError:
        waitProc1 = true
      except CatchableError:
        doAssert(false)
      finally:
        waitProc2 = true

    var fut = waitProc()
    await cancelAndWait(fut)
    check:
      fut.state == FutureState.Completed
      neverFlag1 and neverFlag2 and neverFlag3 and waitProc1 and waitProc2

  asyncTest "Cancellation withTimeout() test":
    var neverFlag1, neverFlag2, neverFlag3: bool
    var waitProc1, waitProc2: bool
    proc neverEndingProc(): Future[void] =
      var res = newFuture[void]()
      proc continuation(udata: pointer) {.gcsafe.} =
        neverFlag2 = true
      proc cancellation(udata: pointer) {.gcsafe.} =
        neverFlag3 = true
      res.addCallback(continuation)
      res.cancelCallback = cancellation
      neverFlag1 = true
      res

    proc withTimeoutProc() {.async.} =
      try:
        discard await withTimeout(neverEndingProc(), 100.milliseconds)
        doAssert(false)
      except CancelledError:
        waitProc1 = true
      except CatchableError:
        doAssert(false)
      finally:
        waitProc2 = true

    var fut = withTimeoutProc()
    await cancelAndWait(fut)
    check:
      fut.state == FutureState.Completed
      neverFlag1 and neverFlag2 and neverFlag3 and waitProc1 and waitProc2

  asyncTest "Cancellation race test":
    var someFut = newFuture[void]()

    proc raceProc(): Future[void] {.async.} =
      await someFut

    var raceFut1 = raceProc()
    someFut.complete()
    await cancelAndWait(raceFut1)

    someFut = newFuture[void]()
    var raceFut2 = raceProc()
    someFut.fail(newException(ValueError, ""))
    await cancelAndWait(raceFut2)

    someFut = newFuture[void]()
    var raceFut3 = raceProc()
    discard someFut.tryCancel()
    await cancelAndWait(raceFut3)

    check:
      raceFut1.state == FutureState.Completed
      raceFut2.state == FutureState.Failed
      raceFut3.state == FutureState.Cancelled

  asyncTest "asyncSpawn() test":
    proc completeTask1() {.async.} =
      discard

    proc completeTask2() {.async.} =
      await sleepAsync(100.milliseconds)

    proc errorTask() {.async.} =
      if true:
        raise newException(ValueError, "")

    proc cancelTask() {.async.} =
      await sleepAsync(10.seconds)

    block:
      let res =
        try:
          var fut1 = completeTask1()
          var fut2 = completeTask2()
          asyncSpawn fut1
          asyncSpawn fut2
          await sleepAsync(200.milliseconds)
          if not(fut1.finished()) or not(fut2.finished()):
            false
          else:
            if fut1.failed() or fut1.cancelled() or fut2.failed() or
               fut2.cancelled():
              false
            else:
              true
        except CatchableError:
          false
      check res

    block:
      let res =
        try:
          asyncSpawn errorTask()
          false
        except FutureDefect:
          true
        except CatchableError:
          false
      check res

    block:
      let res =
        try:
          var fut = cancelTask()
          await cancelAndWait(fut)
          asyncSpawn fut
          false
        except FutureDefect:
          true
        except CatchableError:
          false
      check res

  test "location test":
    # WARNING: This test is very sensitive to line numbers and module name.

    proc macroFuture() {.async.} =
      let someVar {.used.} = 5           # LINE POSITION 1
      let someOtherVar {.used.} = 4
      if true:
        let otherVar {.used.} = 3        # LINE POSITION 2

    template templateFuture(): untyped =
      newFuture[void]("template")

    proc procFuture(): Future[void] =
      newFuture[void]("procedure")       # LINE POSITION 5

    var fut1 = macroFuture()
    var fut2 = templateFuture()          # LINE POSITION 3
    var fut3 = procFuture()

    fut2.complete()                      # LINE POSITION 4
    fut3.complete()                      # LINE POSITION 6

    {.push warning[Deprecated]: off.} # testing backwards compatibility interface
    let loc10 = fut1.location[0]
    let loc11 = fut1.location[1]
    let loc20 = fut2.location[0]
    let loc21 = fut2.location[1]
    let loc30 = fut3.location[0]
    let loc31 = fut3.location[1]
    {.pop.}

    proc chk(loc: ptr SrcLoc, file: string, line: int,
             procedure: string): bool =
      if len(procedure) == 0:
        (loc.line == line) and ($loc.file  == file)
      else:
        (loc.line == line) and ($loc.file  == file) and
        (loc.procedure == procedure)

    check:
      chk(loc10, "testfut.nim", 1225, "macroFuture")
      chk(loc11, "testfut.nim", 1228, "")
      chk(loc20, "testfut.nim", 1237, "template")
      chk(loc21, "testfut.nim", 1240, "")
      chk(loc30, "testfut.nim", 1234, "procedure")
      chk(loc31, "testfut.nim", 1241, "")

  asyncTest "withTimeout(fut) should wait cancellation test":
    proc futureNeverEnds(): Future[void] =
      newFuture[void]("neverending.future")

    proc futureOneLevelMore() {.async.} =
      await futureNeverEnds()

    let res =
      block:
        var fut = futureOneLevelMore()
        try:
          let res = await withTimeout(fut, 100.milliseconds)
          # Because `fut` is never-ending Future[T], `withTimeout` should return
          # `false` but it also has to wait until `fut` is cancelled.
          if not(res) and fut.cancelled():
            true
          else:
            false
        except CatchableError:
          false
    check res

  asyncTest "wait(fut) should wait cancellation test":
    proc futureNeverEnds(): Future[void] =
      newFuture[void]("neverending.future")

    proc futureOneLevelMore() {.async.} =
      await futureNeverEnds()

    var fut = futureOneLevelMore()
    let res =
      try:
        await wait(fut, 100.milliseconds)
        false
      except AsyncTimeoutError:
        # Because `fut` is never-ending Future[T], `wait` should raise
        # `AsyncTimeoutError`, but only after `fut` is cancelled.
        if fut.cancelled():
          true
        else:
          false
      except CatchableError:
        false

    check res

  test "race(zero) test":
    var tseq = newSeq[FutureBase]()
    var fut1 = race(tseq)
    check:
      # https://github.com/nim-lang/Nim/issues/22964
      not compiles(block:
        var fut2 = race())
      not compiles(block:
        var fut3 = race([]))

    check:
      fut1.failed()
      # fut2.failed()
      # fut3.failed()

  asyncTest "race(varargs) test":
    proc vlient1() {.async.} =
      await sleepAsync(100.milliseconds)

    proc vlient2() {.async.} =
      await sleepAsync(200.milliseconds)

    proc vlient3() {.async.} =
      await sleepAsync(300.milliseconds)

    proc ilient1(): Future[int] {.async.} =
      await sleepAsync(100.milliseconds)
      result = 10

    proc ilient2(): Future[int] {.async.} =
      await sleepAsync(200.milliseconds)
      result = 20

    proc ilient3(): Future[int] {.async.} =
      await sleepAsync(300.milliseconds)
      result = 30

    proc slient1(): Future[string] {.async.} =
      await sleepAsync(100.milliseconds)
      result = "sclient1"

    proc slient2(): Future[string] {.async.} =
      await sleepAsync(200.milliseconds)
      result = "sclient2"

    proc slient3(): Future[string] {.async.} =
      await sleepAsync(300.milliseconds)
      result = "sclient3"

    var fut11 = vlient1()
    var fut12 = ilient2()
    var fut13 = slient3()
    var res1 = await race(fut11, fut12, fut13)
    check FutureBase(fut11) == res1
    await allFutures(fut12, fut13)

    var fut21 = vlient2()
    var fut22 = ilient1()
    var fut23 = slient3()
    var res2 = await race(fut21, fut22, fut23)
    check FutureBase(fut22) == res2
    await allFutures(fut21, fut23)

    var fut31 = vlient3()
    var fut32 = ilient2()
    var fut33 = slient1()
    var res3 = await race(fut31, fut32, fut33)
    check FutureBase(fut33) == res3
    await allFutures(fut31, fut32)

    var fut41 = vlient1()
    var fut42 = slient2()
    var fut43 = ilient3()
    var res4 = await race(fut41, fut42, fut43)
    check FutureBase(fut41) == res4
    await allFutures(fut42, fut43)

  asyncTest "race(seq) test":
    proc vlient1() {.async.} =
      await sleepAsync(100.milliseconds)

    proc vlient2() {.async.} =
      await sleepAsync(200.milliseconds)

    proc vlient3() {.async.} =
      await sleepAsync(300.milliseconds)

    proc ilient1(): Future[int] {.async.} =
      await sleepAsync(100.milliseconds)
      result = 10

    proc ilient2(): Future[int] {.async.} =
      await sleepAsync(200.milliseconds)
      result = 20

    proc ilient3(): Future[int] {.async.} =
      await sleepAsync(300.milliseconds)
      result = 30

    proc slient1(): Future[string] {.async.} =
      await sleepAsync(100.milliseconds)
      result = "slient1"

    proc slient2(): Future[string] {.async.} =
      await sleepAsync(200.milliseconds)
      result = "slient2"

    proc slient3(): Future[string] {.async.} =
      await sleepAsync(300.milliseconds)
      result = "slient3"

    var v10 = vlient1()
    var v11 = ilient2()
    var v12 = slient3()
    var res1 = await race(@[FutureBase(v10), FutureBase(v11), FutureBase(v12)])
    check res1 == FutureBase(v10)
    await allFutures(v11, v12)

    var v20 = vlient2()
    var v21 = ilient1()
    var v22 = slient3()
    var res2 = await race(@[FutureBase(v20), FutureBase(v21), FutureBase(v22)])
    check res2 == FutureBase(v21)
    await allFutures(v20, v22)

    var v30 = vlient3()
    var v31 = ilient2()
    var v32 = slient1()
    var res3 = await race(@[FutureBase(v30), FutureBase(v31), FutureBase(v32)])
    check res3 == FutureBase(v32)
    await allFutures(v30, v31)

    var v40 = vlient1()
    var v41 = slient2()
    var v42 = ilient3()
    var res4 = await race(@[FutureBase(v40), FutureBase(v41), FutureBase(v42)])
    check res4 == FutureBase(v40)
    await allFutures(v41, v42)

  asyncTest "race() already completed test":
    proc client1(): Future[int] {.async.} =
      result = 1

    proc client2() {.async.} =
      if true:
        raise newException(ValueError, "")

    proc client3(): Future[string] {.async.} =
      await sleepAsync(100.milliseconds)
      result = "client3"

    var f10 = client1()
    var f20 = client2()
    var f30 = client3()
    var fut1 = race(f30, f10, f20)
    var f11 = client1()
    var f21 = client2()
    var f31 = client3()
    var fut2 = race(f31, f21, f11)

    check:
      fut1.completed() and fut1.read() == FutureBase(f10)
      fut2.completed() and fut2.read() == FutureBase(f21)

    await allFutures(f20, f30, f11, f31)

  asyncTest "race() cancellation test":
    proc client1() {.async.} =
      await sleepAsync(100.milliseconds)

    proc client2(): Future[int] {.async.} =
      await sleepAsync(200.milliseconds)
      return 10

    proc client3(): Future[string] {.async.} =
      await sleepAsync(300.milliseconds)
      return "client3"

    var f1 = client1()
    var f2 = client2()
    var f3 = client3()
    var fut = race(f1, f2, f3)
    await cancelAndWait(fut)

    check:
      not(f1.finished())
      not(f2.finished())
      not(f3.finished())

    await sleepAsync(500.milliseconds)

    check:
      f1.finished()
      f2.finished()
      f3.finished()

  test "Unsigned integer overflow test":
    check:
      0xFFFF_FFFF_FFFF_FFFF'u64 + 1'u64 == 0'u64
      0xFFFF_FFFF'u32 + 1'u32 == 0'u32

    when sizeof(uint) == 8:
      check 0xFFFF_FFFF_FFFF_FFFF'u + 1'u == 0'u
    else:
      check 0xFFFF_FFFF'u + 1'u == 0'u

    var v1_64 = 0xFFFF_FFFF_FFFF_FFFF'u64
    var v2_64 = 0xFFFF_FFFF_FFFF_FFFF'u64
    var v1_32 = 0xFFFF_FFFF'u32
    var v2_32 = 0xFFFF_FFFF'u32
    inc(v1_64)
    inc(v1_32)
    check:
      v1_64 == 0'u64
      v2_64 + 1'u64 == 0'u64
      v1_32 == 0'u32
      v2_32 + 1'u32 == 0'u32

    when sizeof(uint) == 8:
      var v1_u = 0xFFFF_FFFF_FFFF_FFFF'u
      var v2_u = 0xFFFF_FFFF_FFFF_FFFF'u
      inc(v1_u)
      check:
        v1_u == 0'u
        v2_u + 1'u == 0'u
    else:
      var v1_u = 0xFFFF_FFFF'u
      var v2_u = 0xFFFF_FFFF'u
      inc(v1_u)
      check:
        v1_u == 0'u
        v2_u + 1'u == 0'u

  asyncTest "wait() cancellation undefined behavior test #1":
    proc testInnerFoo(fooFut: Future[void]): Future[TestFooConnection] {.
         async.} =
      await fooFut
      return TestFooConnection()

    proc testFoo(fooFut: Future[void]) {.async.} =
      let connection =
        try:
          let res = await testInnerFoo(fooFut).wait(10.seconds)
          Result[TestFooConnection, int].ok(res)
        except CancelledError:
          Result[TestFooConnection, int].err(0)
        except CatchableError:
          Result[TestFooConnection, int].err(1)
      check connection.isOk()

    var future = newFuture[void]("last.child.future")
    var someFut = testFoo(future)
    future.complete()
    discard someFut.tryCancel()
    await someFut

  asyncTest "wait() cancellation undefined behavior test #2":
    proc testInnerFoo(fooFut: Future[void]): Future[TestFooConnection] {.
         async.} =
      await fooFut
      return TestFooConnection()

    proc testMiddleFoo(fooFut: Future[void]): Future[TestFooConnection] {.
         async.} =
      await testInnerFoo(fooFut)

    proc testFoo(fooFut: Future[void]) {.async.} =
      let connection =
        try:
          let res = await testMiddleFoo(fooFut).wait(10.seconds)
          Result[TestFooConnection, int].ok(res)
        except CancelledError:
          Result[TestFooConnection, int].err(0)
        except CatchableError:
          Result[TestFooConnection, int].err(1)
      check connection.isOk()

    var future = newFuture[void]("last.child.future")
    var someFut = testFoo(future)
    future.complete()
    discard someFut.tryCancel()
    await someFut

  asyncTest "withTimeout() cancellation undefined behavior test #1":
    proc testInnerFoo(fooFut: Future[void]): Future[TestFooConnection] {.
         async.} =
      await fooFut
      return TestFooConnection()

    proc testFoo(fooFut: Future[void]) {.async.} =
      let connection =
        try:
          let
            checkFut = testInnerFoo(fooFut)
            res = await withTimeout(checkFut, 10.seconds)
          if res:
            Result[TestFooConnection, int].ok(checkFut.value)
          else:
            Result[TestFooConnection, int].err(0)
        except CancelledError:
          Result[TestFooConnection, int].err(1)
        except CatchableError:
          Result[TestFooConnection, int].err(2)
      check connection.isOk()

    var future = newFuture[void]("last.child.future")
    var someFut = testFoo(future)
    future.complete()
    discard someFut.tryCancel()
    await someFut

  asyncTest "withTimeout() cancellation undefined behavior test #2":
    proc testInnerFoo(fooFut: Future[void]): Future[TestFooConnection] {.
         async.} =
      await fooFut
      return TestFooConnection()

    proc testMiddleFoo(fooFut: Future[void]): Future[TestFooConnection] {.
         async.} =
      await testInnerFoo(fooFut)

    proc testFoo(fooFut: Future[void]) {.async.} =
      let connection =
        try:
          let
            checkFut = testMiddleFoo(fooFut)
            res = await withTimeout(checkFut, 10.seconds)
          if res:
            Result[TestFooConnection, int].ok(checkFut.value)
          else:
            Result[TestFooConnection, int].err(0)
        except CancelledError:
          Result[TestFooConnection, int].err(1)
        except CatchableError:
          Result[TestFooConnection, int].err(2)
      check connection.isOk()

    var future = newFuture[void]("last.child.future")
    var someFut = testFoo(future)
    future.complete()
    discard someFut.tryCancel()
    await someFut

  asyncTest "Cancellation behavior test":
    proc testInnerFoo(fooFut: Future[void]) {.async.} =
      await fooFut

    proc testMiddleFoo(fooFut: Future[void]) {.async.} =
      await testInnerFoo(fooFut)

    proc testOuterFoo(fooFut: Future[void]) {.async.} =
      await testMiddleFoo(fooFut)

    block:
      # Cancellation of pending Future
      let future = newFuture[void]("last.child.pending.future")
      await cancelAndWait(future)
      check:
        future.cancelled() == true

    block:
      # Cancellation of completed Future
      let future = newFuture[void]("last.child.completed.future")
      future.complete()
      await cancelAndWait(future)
      check:
        future.cancelled() == false
        future.completed() == true

    block:
      # Cancellation of failed Future
      let future = newFuture[void]("last.child.failed.future")
      future.fail(newException(ValueError, "ABCD"))
      await cancelAndWait(future)
      check:
        future.cancelled() == false
        future.failed() == true

    block:
      # Cancellation of already cancelled Future
      let future = newFuture[void]("last.child.cancelled.future")
      future.cancelAndSchedule()
      await cancelAndWait(future)
      check:
        future.cancelled() == true

    block:
      # Cancellation of Pending->Pending->Pending->Pending sequence
      let future = newFuture[void]("last.child.pending.future")
      let testFut = testOuterFoo(future)
      await cancelAndWait(testFut)
      check:
        testFut.cancelled() == true

    block:
      # Cancellation of Pending->Pending->Pending->Completed sequence
      let future = newFuture[void]("last.child.completed.future")
      let testFut = testOuterFoo(future)
      future.complete()
      await cancelAndWait(testFut)
      check:
        testFut.cancelled() == false
        testFut.completed() == true

    block:
      # Cancellation of Pending->Pending->Pending->Failed sequence
      let future = newFuture[void]("last.child.failed.future")
      let testFut = testOuterFoo(future)
      future.fail(newException(ValueError, "ABCD"))
      await cancelAndWait(testFut)
      check:
        testFut.cancelled() == false
        testFut.failed() == true

    block:
      # Cancellation of Pending->Pending->Pending->Cancelled sequence
      let future = newFuture[void]("last.child.cancelled.future")
      let testFut = testOuterFoo(future)
      future.cancelAndSchedule()
      await cancelAndWait(testFut)
      check:
        testFut.cancelled() == true

    block:
      # Cancellation of pending Future, when automatic scheduling disabled
      let future = newFuture[void]("last.child.pending.future",
                                   {FutureFlag.OwnCancelSchedule})
      proc cancellation(udata: pointer) {.gcsafe.} =
        discard
      future.cancelCallback = cancellation
      # Note, future will never be finished in such case, until we manually not
      # finish it
      let cancelFut = cancelAndWait(future)
      await sleepAsync(100.milliseconds)
      check:
        cancelFut.finished() == false
        future.cancelled() == false
      # Now we manually changing Future's state, so `cancelAndWait` could
      # finish
      future.complete()
      await cancelFut
      check:
        cancelFut.finished() == true
        future.cancelled() == false
        future.finished() == true

    block:
      # Cancellation of pending Future, which will fail Future on cancellation,
      # when automatic scheduling disabled
      let future = newFuture[void]("last.child.completed.future",
                                   {FutureFlag.OwnCancelSchedule})
      proc cancellation(udata: pointer) {.gcsafe.} =
        future.complete()
      future.cancelCallback = cancellation
      # Note, future will never be finished in such case, until we manually not
      # finish it
      await cancelAndWait(future)
      check:
        future.cancelled() == false
        future.completed() == true

    block:
      # Cancellation of pending Future, which will fail Future on cancellation,
      # when automatic scheduling disabled
      let future = newFuture[void]("last.child.failed.future",
                                   {FutureFlag.OwnCancelSchedule})
      proc cancellation(udata: pointer) {.gcsafe.} =
        future.fail(newException(ValueError, "ABCD"))
      future.cancelCallback = cancellation
      # Note, future will never be finished in such case, until we manually not
      # finish it
      await cancelAndWait(future)
      check:
        future.cancelled() == false
        future.failed() == true

    block:
      # Cancellation of pending Future, which will fail Future on cancellation,
      # when automatic scheduling disabled
      let future = newFuture[void]("last.child.cancelled.future",
                                   {FutureFlag.OwnCancelSchedule})
      proc cancellation(udata: pointer) {.gcsafe.} =
        future.cancelAndSchedule()
      future.cancelCallback = cancellation
      # Note, future will never be finished in such case, until we manually not
      # finish it
      await cancelAndWait(future)
      check:
        future.cancelled() == true

    block:
      # Cancellation of pending Pending->Pending->Pending->Pending, when
      # automatic scheduling disabled and Future do nothing in cancellation
      # callback
      let future = newFuture[void]("last.child.pending.future",
                                   {FutureFlag.OwnCancelSchedule})
      proc cancellation(udata: pointer) {.gcsafe.} =
        discard
      future.cancelCallback = cancellation
      # Note, future will never be finished in such case, until we manually not
      # finish it
      let testFut = testOuterFoo(future)
      let cancelFut = cancelAndWait(testFut)
      await sleepAsync(100.milliseconds)
      check:
        cancelFut.finished() == false
        testFut.cancelled() == false
        future.cancelled() == false
      # Now we manually changing Future's state, so `cancelAndWait` could
      # finish
      future.complete()
      await cancelFut
      check:
        cancelFut.finished() == true
        future.cancelled() == false
        future.finished() == true
        testFut.cancelled() == false
        testFut.finished() == true

    block:
      # Cancellation of pending Pending->Pending->Pending->Pending, when
      # automatic scheduling disabled and Future completes in cancellation
      # callback
      let future = newFuture[void]("last.child.pending.future",
                                   {FutureFlag.OwnCancelSchedule})
      proc cancellation(udata: pointer) {.gcsafe.} =
        future.complete()
      future.cancelCallback = cancellation
      # Note, future will never be finished in such case, until we manually not
      # finish it
      let testFut = testOuterFoo(future)
      await cancelAndWait(testFut)
      await sleepAsync(100.milliseconds)
      check:
        testFut.cancelled() == false
        testFut.finished() == true
        future.cancelled() == false
        future.finished() == true

    block:
      # Cancellation of pending Pending->Pending->Pending->Pending, when
      # automatic scheduling disabled and Future fails in cancellation callback
      let future = newFuture[void]("last.child.pending.future",
                                   {FutureFlag.OwnCancelSchedule})
      proc cancellation(udata: pointer) {.gcsafe.} =
        future.fail(newException(ValueError, "ABCD"))
      future.cancelCallback = cancellation
      # Note, future will never be finished in such case, until we manually not
      # finish it
      let testFut = testOuterFoo(future)
      await cancelAndWait(testFut)
      await sleepAsync(100.milliseconds)
      check:
        testFut.cancelled() == false
        testFut.failed() == true
        future.cancelled() == false
        future.failed() == true

    block:
      # Cancellation of pending Pending->Pending->Pending->Pending, when
      # automatic scheduling disabled and Future fails in cancellation callback
      let future = newFuture[void]("last.child.pending.future",
                                   {FutureFlag.OwnCancelSchedule})
      proc cancellation(udata: pointer) {.gcsafe.} =
        future.cancelAndSchedule()
      future.cancelCallback = cancellation
      # Note, future will never be finished in such case, until we manually not
      # finish it
      let testFut = testOuterFoo(future)
      await cancelAndWait(testFut)
      await sleepAsync(100.milliseconds)
      check:
        testFut.cancelled() == true
        future.cancelled() == true

  test "Issue #334 test":
    proc test(): bool =
      var testres = ""

      proc a() {.async.} =
        try:
          await sleepAsync(seconds(1))
        except CatchableError as exc:
          testres.add("A")
          raise exc

      proc b() {.async.} =
        try:
          await a()
        except CatchableError as exc:
          testres.add("B")
          raise exc

      proc c() {.async.} =
        try:
          echo $(await b().withTimeout(seconds(2)))
        except CatchableError as exc:
          testres.add("C")
          raise exc

      let x = c()
      x.cancelSoon()

      try:
        waitFor x
      except CatchableError:
        testres.add("D")

      testres.add("E")

      waitFor sleepAsync(milliseconds(100))

      testres == "ABCDE"

    check test() == true

  asyncTest "cancelAndWait() should be able to cancel test":
    proc test1() {.async.} =
      await noCancel sleepAsync(100.milliseconds)
      await noCancel sleepAsync(100.milliseconds)
      await sleepAsync(100.milliseconds)

    proc test2() {.async.} =
      await noCancel sleepAsync(100.milliseconds)
      await sleepAsync(100.milliseconds)
      await noCancel sleepAsync(100.milliseconds)

    proc test3() {.async.} =
      await sleepAsync(100.milliseconds)
      await noCancel sleepAsync(100.milliseconds)
      await noCancel sleepAsync(100.milliseconds)

    proc test4() {.async.} =
      while true:
        await noCancel sleepAsync(50.milliseconds)
        await sleepAsync(0.milliseconds)

    proc test5() {.async.} =
      while true:
        await sleepAsync(0.milliseconds)
        await noCancel sleepAsync(50.milliseconds)

    block:
      let future1 = test1()
      await cancelAndWait(future1)
      let future2 = test1()
      await sleepAsync(10.milliseconds)
      await cancelAndWait(future2)
      check:
        future1.cancelled() == true
        future2.cancelled() == true

    block:
      let future1 = test2()
      await cancelAndWait(future1)
      let future2 = test2()
      await sleepAsync(10.milliseconds)
      await cancelAndWait(future2)
      check:
        future1.cancelled() == true
        future2.cancelled() == true

    block:
      let future1 = test3()
      await cancelAndWait(future1)
      let future2 = test3()
      await sleepAsync(10.milliseconds)
      await cancelAndWait(future2)
      check:
        future1.cancelled() == true
        future2.cancelled() == true

    block:
      let future1 = test4()
      await cancelAndWait(future1)
      let future2 = test4()
      await sleepAsync(333.milliseconds)
      await cancelAndWait(future2)
      check:
        future1.cancelled() == true
        future2.cancelled() == true

    block:
      let future1 = test5()
      await cancelAndWait(future1)
      let future2 = test5()
      await sleepAsync(333.milliseconds)
      await cancelAndWait(future2)
      check:
        future1.cancelled() == true
        future2.cancelled() == true
  test "Sink with literals":
    # https://github.com/nim-lang/Nim/issues/22175
    let fut = newFuture[string]()
    fut.complete("test")
    check:
      fut.value() == "test"