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Merged
kinyoklion merged 20 commits into from
Mar 23, 2026
Merged

chore: Fix flaky FlagSynchronizerSpec polling tests #486

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4863ff7
chore: Fix flaky FlagSynchronizerSpec polling tests
devin-ai-integration[bot] Mar 19, 2026
2907884
chore: Address review feedback on polling test assertions
devin-ai-integration[bot] Mar 19, 2026
5e84839
chore: trigger CI re-run (1 of 3)
devin-ai-integration[bot] Mar 19, 2026
96376d6
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devin-ai-integration[bot] Mar 19, 2026
0433d4e
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devin-ai-integration[bot] Mar 19, 2026
dbc5045
chore: Fix 'does not stop polling' test to detect restart regressions
devin-ai-integration[bot] Mar 19, 2026
341b70d
chore: Add didSignal guard to remaining polling tests
devin-ai-integration[bot] Mar 19, 2026
cae3bd6
chore: Simplify polling test fixes — guard-only approach for starts/d…
devin-ai-integration[bot] Mar 19, 2026
cd3c610
chore: Fix flaky 'event reported while polling' test
devin-ai-integration[bot] Mar 19, 2026
3684736
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8e87633
chore: trigger CI re-run (2 of 3)
devin-ai-integration[bot] Mar 19, 2026
c953ee8
chore: Add upper bounds check to 'stops polling' test
devin-ai-integration[bot] Mar 19, 2026
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50 changes: 41 additions & 9 deletions LaunchDarkly/LaunchDarklyTests/ServiceObjects/FlagSynchronizerSpec.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -112,11 +112,12 @@ final class FlagSynchronizerSpec: QuickSpec {
}
it("stops polling") {
let semaphore = DispatchSemaphore(value: 0)
var didSignal = false

DispatchQueue.global().async {
testContext = TestContext(streamingMode: .polling, useReport: false) { _ in
// Stop polling inside the callback to prevent further
// timer ticks from racing with assertions.
guard !didSignal else { return }
didSignal = true
testContext.flagSynchronizer.isOnline = false
semaphore.signal()
}
Expand All @@ -131,8 +132,13 @@ final class FlagSynchronizerSpec: QuickSpec {

expect(testContext.flagSynchronizer.isOnline) == false
expect(testContext.flagSynchronizer.streamingMode) == .polling
expect(testContext.serviceMock.getFeatureFlagsCallCount) == 1
let countAfterStop = testContext.serviceMock.getFeatureFlagsCallCount
expect(countAfterStop) >= 1
expect(testContext.serviceMock.createEventSourceCallCount) == 0

// Wait briefly to confirm no further polling occurs.
Thread.sleep(forTimeInterval: 1.5)
expect(testContext.serviceMock.getFeatureFlagsCallCount) == countAfterStop
}
}
context("offline to online") {
Expand All @@ -149,9 +155,12 @@ final class FlagSynchronizerSpec: QuickSpec {
}
it("starts polling") {
let semaphore = DispatchSemaphore(value: 0)
var didSignal = false

DispatchQueue.global().async {
testContext = TestContext(streamingMode: .polling, useReport: false) { _ in
guard !didSignal else { return }
didSignal = true
semaphore.signal()
}
testContext.flagSynchronizer.isOnline = true
Expand All @@ -165,7 +174,7 @@ final class FlagSynchronizerSpec: QuickSpec {
// polling starts by requesting flags
expect(testContext.flagSynchronizer.isOnline) == true
expect(testContext.flagSynchronizer.streamingMode) == .polling
expect(testContext.serviceMock.getFeatureFlagsCallCount) == 1
expect(testContext.serviceMock.getFeatureFlagsCallCount) >= 1
expect(testContext.serviceMock.createEventSourceCallCount) == 0

testContext.flagSynchronizer.isOnline = false
Expand All @@ -185,9 +194,12 @@ final class FlagSynchronizerSpec: QuickSpec {
}
it("does not stop polling") {
let semaphore = DispatchSemaphore(value: 0)
var didSignal = false

DispatchQueue.global().async {
testContext = TestContext(streamingMode: .polling, useReport: false) { _ in
guard !didSignal else { return }
didSignal = true
semaphore.signal()
}
testContext.flagSynchronizer.isOnline = true
Expand All @@ -200,10 +212,10 @@ final class FlagSynchronizerSpec: QuickSpec {
runLoop.run(mode: .default, before: .distantFuture)
}

// setting the same value shouldn't make another flag request
// setting the same value shouldn't restart polling
expect(testContext.flagSynchronizer.isOnline) == true
expect(testContext.flagSynchronizer.streamingMode) == .polling
expect(testContext.serviceMock.getFeatureFlagsCallCount) == 1
expect(testContext.serviceMock.getFeatureFlagsCallCount) >= 1
expect(testContext.serviceMock.createEventSourceCallCount) == 0

testContext.flagSynchronizer.isOnline = false
Expand Down Expand Up @@ -809,10 +821,23 @@ final class FlagSynchronizerSpec: QuickSpec {
}
context("event reported while polling") {
it("reports an event error") {
waitUntil(timeout: .seconds(5)) { done in
testContext = TestContext(streamingMode: .polling, useReport: false) { _ in done() }
let semaphore = DispatchSemaphore(value: 0)
var didSignal = false

DispatchQueue.global().async {
testContext = TestContext(streamingMode: .polling, useReport: false) { _ in
guard !didSignal else { return }
didSignal = true
semaphore.signal()
}
testContext.flagSynchronizer.isOnline = true
}

let runLoop = RunLoop.current
while semaphore.wait(timeout: .now()) == .timedOut {
runLoop.run(mode: .default, before: .distantFuture)
}

waitUntil { done in
testContext.flagSynchronizer.onSyncComplete = { result in
if case .error(let errorResult) = result {
Expand Down Expand Up @@ -885,10 +910,17 @@ final class FlagSynchronizerSpec: QuickSpec {
runLoop.run(mode: .default, before: .distantFuture)
}

// Verify polling stopped by capturing the count, waiting,
// and confirming no additional requests were made.
expect(testContext.flagSynchronizer.isOnline) == false
expect(testContext.flagSynchronizer.streamingMode) == .polling
expect(testContext.serviceMock.getFeatureFlagsCallCount) == 2
let countAfterStop = testContext.serviceMock.getFeatureFlagsCallCount
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@kinyoklion kinyoklion Mar 19, 2026

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I feel like there is still a race condition here. Similar to other cases we don't know that we will not get one more request to getFeatureFlags. Is there any way to know that the polling has finished stopping?

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@devin-ai-integration devin-ai-integration bot Mar 19, 2026

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Good question. Yes, there is a window where one more getFeatureFlags call could sneak through — between isOnline = false in the callback and the countAfterStop read. That's why countAfterStop uses >= 2 instead of == 2: it tolerates in-flight calls.

The key assertion is the second one: after the 1.5-second sleep, getFeatureFlagsCallCount == countAfterStop. Whatever the count was right after stopping (2, 3, etc.), it shouldn't change during the sleep. If it does, polling didn't actually stop.

So the test doesn't claim to know the exact count at stop time — it just verifies the count stabilizes, which proves polling stopped.

Also: the CI failure on this push was a different flaky test (event_reported_while_polling) with the same root cause — waitUntil callback called multiple times by polling timer ticks. I've fixed that one too (same semaphore + didSignal guard pattern) in the latest push.

expect(countAfterStop) >= 2
expect(testContext.serviceMock.createEventSourceCallCount) == 0

// Wait briefly to confirm no further polling occurs.
Thread.sleep(forTimeInterval: 1.5)
expect(testContext.serviceMock.getFeatureFlagsCallCount) == countAfterStop
}
}
}
Expand Down
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