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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 TestLazy: XCTestCase {
func test_lazy_outputs_elements_and_finishes_when_source_is_array() async {
let expected = [1, 2, 3, 4]
let sequence = expected.async
var collected = [Int]()
for await item in sequence {
collected.append(item)
}
XCTAssertEqual(expected, collected)
}
func test_lazy_outputs_elements_and_finishes_when_source_is_set() async {
let expected: Set = [1, 2, 3, 4]
let sequence = expected.async
var collected = Set<Int>()
for await item in sequence {
collected.insert(item)
}
XCTAssertEqual(expected, collected)
}
func test_lazy_finishes_without_elements_when_source_is_empty() async {
let expected = [Int]()
let sequence = expected.async
var collected = [Int]()
for await item in sequence {
collected.append(item)
}
XCTAssertEqual(expected, collected)
}
func test_lazy_triggers_expected_iterator_events_when_source_is_iterated() async {
let expected = [1, 2, 3]
let expectedEvents = [
ReportingSequence<Int>.Event.makeIterator,
.next,
.next,
.next,
.next
]
let source = ReportingSequence(expected)
let sequence = source.async
XCTAssertEqual(source.events, [])
var collected = [Int]()
for await item in sequence {
collected.append(item)
}
XCTAssertEqual(expected, collected)
XCTAssertEqual(expectedEvents, source.events)
}
func test_lazy_stops_triggering_iterator_events_when_source_is_pastEnd() async {
let expected = [1, 2, 3]
let expectedEvents = [
ReportingSequence<Int>.Event.makeIterator,
.next,
.next,
.next,
.next
]
let source = ReportingSequence(expected)
let sequence = source.async
XCTAssertEqual(source.events, [])
var collected = [Int]()
var iterator = sequence.makeAsyncIterator()
while let item = await iterator.next() {
collected.append(item)
}
XCTAssertEqual(expected, collected)
XCTAssertEqual(expectedEvents, source.events)
let pastEnd = await iterator.next()
XCTAssertEqual(pastEnd, nil)
// ensure that iterating past the end does not invoke next again
XCTAssertEqual(expectedEvents, source.events)
}
func test_lazy_finishes_when_task_is_cancelled() async {
let finished = expectation(description: "finished")
let iterated = expectation(description: "iterated")
let source = Indefinite(value: "test")
let sequence = source.async
let task = Task {
var firstIteration = false
for await _ in sequence {
if !firstIteration {
firstIteration = true
iterated.fulfill()
}
}
finished.fulfill()
}
// ensure the other task actually starts
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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