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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift Async Algorithms open source project
//
// Copyright (c) 2022 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
//
//===----------------------------------------------------------------------===//
import XCTest
import AsyncAlgorithms
final class TestBufferedByteIterator: XCTestCase {
actor Isolated<T: Sendable> {
var value: T
init(_ value: T) {
self.value = value
}
func update(_ value: T) async {
self.value = value
}
}
func test_immediately_empty() async throws {
let reloaded = Isolated(false)
var iterator = AsyncBufferedByteIterator(capacity: 3) { buffer in
XCTAssertEqual(buffer.count, 3)
await reloaded.update(true)
return 0
}
var wasReloaded = await reloaded.value
XCTAssertFalse(wasReloaded)
let byte = try await iterator.next()
XCTAssertNil(byte)
wasReloaded = await reloaded.value
XCTAssertTrue(wasReloaded)
}
func test_one_pass() async throws {
let reloaded = Isolated(0)
var iterator = AsyncBufferedByteIterator(capacity: 3) { buffer in
XCTAssertEqual(buffer.count, 3)
let count = await reloaded.value
await reloaded.update(count + 1)
if count >= 1 {
return 0
}
buffer.copyBytes(from: [1, 2, 3])
return 3
}
var reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, 0)
var byte = try await iterator.next()
XCTAssertEqual(byte, 1)
reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, 1)
byte = try await iterator.next()
XCTAssertEqual(byte, 2)
reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, 1)
byte = try await iterator.next()
XCTAssertEqual(byte, 3)
reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, 1)
byte = try await iterator.next()
XCTAssertNil(byte)
reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, 2)
byte = try await iterator.next()
XCTAssertNil(byte)
reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, 2)
}
func test_three_pass() async throws {
let reloaded = Isolated(0)
var iterator = AsyncBufferedByteIterator(capacity: 3) { buffer in
XCTAssertEqual(buffer.count, 3)
let count = await reloaded.value
await reloaded.update(count + 1)
if count >= 3 {
return 0
}
buffer.copyBytes(from: [1, 2, 3])
return 3
}
var reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, 0)
for n in 1...3 {
var byte = try await iterator.next()
XCTAssertEqual(byte, 1)
reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, n)
byte = try await iterator.next()
XCTAssertEqual(byte, 2)
reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, n)
byte = try await iterator.next()
XCTAssertEqual(byte, 3)
reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, n)
}
var byte = try await iterator.next()
XCTAssertNil(byte)
reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, 4)
byte = try await iterator.next()
XCTAssertNil(byte)
reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, 4)
}
func test_three_pass_throwing() async throws {
let reloaded = Isolated(0)
var iterator = AsyncBufferedByteIterator(capacity: 3) { buffer in
XCTAssertEqual(buffer.count, 3)
let count = await reloaded.value
await reloaded.update(count + 1)
if count >= 3 {
return 0
}
if count == 2 {
throw Failure()
}
buffer.copyBytes(from: [1, 2, 3])
return 3
}
var reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, 0)
for n in 1...3 {
do {
var byte = try await iterator.next()
XCTAssertEqual(byte, 1)
reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, n)
byte = try await iterator.next()
XCTAssertEqual(byte, 2)
reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, n)
byte = try await iterator.next()
XCTAssertEqual(byte, 3)
reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, n)
} catch {
XCTAssertEqual(n, 3)
break
}
}
var byte = try await iterator.next()
XCTAssertNil(byte)
reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, 3)
byte = try await iterator.next()
XCTAssertNil(byte)
reloadCount = await reloaded.value
XCTAssertEqual(reloadCount, 3)
}
func test_cancellation() async {
struct RepeatingBytes: AsyncSequence {
typealias Element = UInt8
func makeAsyncIterator() -> AsyncBufferedByteIterator {
AsyncBufferedByteIterator(capacity: 3) { buffer in
buffer.copyBytes(from: [1, 2, 3])
return 3
}
}
}
let finished = expectation(description: "finished")
let iterated = expectation(description: "iterated")
let task = Task {
var firstIteration = false
do {
for try await _ in RepeatingBytes() {
if !firstIteration {
iterated.fulfill()
firstIteration = true
}
}
XCTFail("expected to throw a cancellation error")
} catch {
if error is CancellationError {
finished.fulfill()
}
}
}
await fulfillment(of: [iterated], timeout: 1.0)
// cancellation should ensure the loop finishes
// without regards to the remaining underlying sequence
task.cancel()
await fulfillment(of: [finished], timeout: 1.0)
}
}
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