Listing tests with empty LinuxMain.swift outputs error message (Swift 5.8)

[adam-fowler]

Description

Running swift test list outputs an error for SwiftPM packages that have an empty LinuxMain.swift

Expected behavior

swift test list to output a list of all the tests in a package

Actual behavior

It outputs

error: malformed

Steps to reproduce

1. swift package init
2. touch Tests/LinuxMain.swift
3. swift test list

Swift Package Manager version/commit hash

No response

Swift & OS version (output of swift --version && uname -a)

Swift version 5.8-dev (LLVM f6b60d5b8f4b443, Swift ecccce61139bbc4)
Target: x86_64-unknown-linux-gnu
Linux af-starbook 5.15.0-46-generic #49~20.04.1-Ubuntu SMP Thu Aug 4 19:15:44 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

[tomerd]

@adam-fowler is this still an issue?

❯ swift test --list-tests
[1/1] Planning buildCompiling plugin Swift-DocC...
Compiling plugin Swift-DocC Preview...
Building for debugging...
Build complete! (0.78s)
MQTTNIOTests.AsyncMQTTNIOTests/testAsyncSequencePublishListener
MQTTNIOTests.AsyncMQTTNIOTests/testAsyncSequencePublishSubscriptionIdListener
MQTTNIOTests.AsyncMQTTNIOTests/testConnect
MQTTNIOTests.AsyncMQTTNIOTests/testPing
MQTTNIOTests.AsyncMQTTNIOTests/testPublishSubscribe
MQTTNIOTests.CoreMQTTTests/testConnect
MQTTNIOTests.CoreMQTTTests/testPublish
MQTTNIOTests.CoreMQTTTests/testSubscribe
MQTTNIOTests.MQTTNIOTests/testCloseListener
MQTTNIOTests.MQTTNIOTests/testConnectWithUsernameAndPassword
MQTTNIOTests.MQTTNIOTests/testConnectWithWill
MQTTNIOTests.MQTTNIOTests/testConnectWithWrongUsernameAndPassword
MQTTNIOTests.MQTTNIOTests/testDoubleConnect
MQTTNIOTests.MQTTNIOTests/testDoubleShutdown
MQTTNIOTests.MQTTNIOTests/testInflight
MQTTNIOTests.MQTTNIOTests/testListenerReferenceCycle
MQTTNIOTests.MQTTNIOTests/testMQTTPingreq
MQTTNIOTests.MQTTNIOTests/testMQTTPublishQoS0
MQTTNIOTests.MQTTNIOTests/testMQTTPublishQoS1
MQTTNIOTests.MQTTNIOTests/testMQTTPublishQoS2
MQTTNIOTests.MQTTNIOTests/testMQTTPublishRetain
MQTTNIOTests.MQTTNIOTests/testMQTTPublishToClient
MQTTNIOTests.MQTTNIOTests/testMQTTPublishToClientLargePayload
MQTTNIOTests.MQTTNIOTests/testMQTTServerClose
MQTTNIOTests.MQTTNIOTests/testMQTTSubscribe
MQTTNIOTests.MQTTNIOTests/testMultipleTasks
MQTTNIOTests.MQTTNIOTests/testPacketId
MQTTNIOTests.MQTTNIOTests/testPersistentSession
MQTTNIOTests.MQTTNIOTests/testPing
MQTTNIOTests.MQTTNIOTests/testRawIPConnect
MQTTNIOTests.MQTTNIOTests/testSessionPresent
MQTTNIOTests.MQTTNIOTests/testSSLConnect
MQTTNIOTests.MQTTNIOTests/testSSLConnectFromP12
MQTTNIOTests.MQTTNIOTests/testSubscribeAll
MQTTNIOTests.MQTTNIOTests/testUnsubscribe
MQTTNIOTests.MQTTNIOTests/testWebsocketAndSSLConnect
MQTTNIOTests.MQTTNIOTests/testWebsocketConnect
MQTTNIOTests.MQTTNIOv5Tests/testAuth
MQTTNIOTests.MQTTNIOv5Tests/testBadAuthenticationMethod
MQTTNIOTests.MQTTNIOv5Tests/testBadPublish
MQTTNIOTests.MQTTNIOv5Tests/testConnect
MQTTNIOTests.MQTTNIOv5Tests/testConnectWithBinaryDataProperty
MQTTNIOTests.MQTTNIOv5Tests/testConnectWithNoIdentifier
MQTTNIOTests.MQTTNIOv5Tests/testConnectWithStringPairProperty
MQTTNIOTests.MQTTNIOv5Tests/testConnectWithUInt16Property
MQTTNIOTests.MQTTNIOv5Tests/testConnectWithUInt32Property
MQTTNIOTests.MQTTNIOv5Tests/testConnectWithUInt8Property
MQTTNIOTests.MQTTNIOv5Tests/testConnectWithWill
MQTTNIOTests.MQTTNIOv5Tests/testInvalidTopicName
MQTTNIOTests.MQTTNIOv5Tests/testMQTTContentType
MQTTNIOTests.MQTTNIOv5Tests/testMQTTSubscribe
MQTTNIOTests.MQTTNIOv5Tests/testMQTTSubscribeFlags
MQTTNIOTests.MQTTNIOv5Tests/testOutOfRangeTopicAlias
MQTTNIOTests.MQTTNIOv5Tests/testPersistentSession
MQTTNIOTests.MQTTNIOv5Tests/testPublishQoS1
MQTTNIOTests.MQTTNIOv5Tests/testPublishQoS1WithProperty
MQTTNIOTests.MQTTNIOv5Tests/testPublishQoS2
MQTTNIOTests.MQTTNIOv5Tests/testPublishWithSubscription
MQTTNIOTests.MQTTNIOv5Tests/testSessionPresent
MQTTNIOTests.MQTTNIOv5Tests/testSubscribeAll
MQTTNIOTests.MQTTNIOv5Tests/testUnsubscribe
MQTTNIOTests.MQTTNIOv5Tests/testUserProperty

[adam-fowler]

Going to close this just now as I cannot replicate it.

[adam-fowler]

Re-opening, just managed to replicate this.

[adam-fowler]

It looks like it is related to packages that have a LinuxMain.swift

[MaxDesiatov]

Assuming we don't support LinuxMain.swift anymore IIRC, do we need a separate issue or to reopen this one to track that the error message itself should be fixed?

[adam-fowler]

A 5.8 release of swift should not have breaking changes in it though. Projects that built and test fine with swift 5.7 should do so with 5.8 as well.

[MaxDesiatov]

Right, so reopening this one seems more suitable then?

[adam-fowler]

I closed this issue then within 5 minutes realised it was still an issue so reopened it and managed to narrow down what the problem was.

[MaxDesiatov]

Ah, ok. I was a bit confused since the status for me is still showing up as closed.

[adam-fowler]

Ah, ok. I was a bit confused since the status for me is still showing up as closed.

Ha I'm an idiot, forgot to re-open it

[adam-fowler]

I've also worked out the LinuxMain.swift needs to empty for the issue to occur. See https://forums.swift.org/t/test-discovery-on-linux/26203/10 for reasons why you might have an empty LinuxMain.swift

[finagolfin]

@adam-fowler, some diagnostics for this error were just merged in trunk, #6860, try it with the next trunk snapshot build- the current Aug. 25 snapshot doesn't have that commit- and see if it helps.

[adam-fowler]

I now get

error: invalid list test JSON structure, produced by /home/adamfowler/Developer/server/mqtt-nio/.build/x86_64-unknown-linux-gnu/debug/mqtt-nioPackageTests.xctest --dump-tests-json, underlying error: malformed(json: "", underlyingError: Error Domain=NSCocoaErrorDomain Code=3840 "The data is not in the correct format.")

[neonichu]

Thanks for the update, sounds like an empty JSON is produced?

[mapedd]

@adam-fowler any luck working around this?

[adam-fowler]

@mapedd I haven't seen this in a long time. Although I've removed LinuxMain.swift from pretty much all of my projects.

[grynspan]

Closing per Adam's latest comment; if somebody's still running into this issue, please do reopen!