UI API called on a background thread problem while testing VLCMediaPlayer

VLCMediaPlayerTest.swift

class MockMediaPlayerDelegate: NSObject, VLCMediaPlayerDelegate {
    
    let stateExpectation: XCTestExpectation?
    
    init(stateExpectation: XCTestExpectation) {
        self.stateExpectation = stateExpectation
    }
    
    func mediaPlayerStateChanged(_ aNotification: Notification!) {
        guard let mediaPlayer = aNotification.object as? VLCMediaPlayer else {
            XCTFail("VLCMediaPlayer is not passed to mejdiaPlayerStateChanged")
            return
        }
        
        if mediaPlayer.state == .playing {
            stateExpectation?.fulfill()
        }
    }
}

class VLCMediaPlayerDelegateTest: XCTestCase {
    
    func testMediaPlayerStateChanged() throws {
        let view = VLCVideoView(frame: .zero)
        let mediaPlayer = try XCTAssertNotNilAndUnwrap(VLCMediaPlayer(videoView: view))
        mediaPlayer.media = Video.test1.media
        
        XCTAssertEqual(mediaPlayer.state, .stopped)

        let states: [VLCMediaPlayerState] = [.opening, .buffering, .esAdded, .playing]
        let expectations = states.map { keyValueObservingMediaState(for: mediaPlayer, state: $0) }
        
        mediaPlayer.play()
        wait(for: expectations, timeout: STANDARD_TIME_OUT)
    }
}

extension XCTestCase {
    func keyValueObservingMediaState(for mediaPlayer: VLCMediaPlayer, state: VLCMediaPlayerState) -> XCTestExpectation {
        return keyValueObservingExpectation(for: mediaPlayer, keyPath: "state", handler: { (obj, _) -> Bool in
            NSLog(String(state.rawValue))
            return (obj as? VLCMediaPlayer)?.state == state
        })
    }
}

On macosx.m:381

NSRect bounds = [sys->glView convertRectToBacking:[sys->glView bounds]]; 

Xcode raises a SIGABRT signal with the following message

Main Thread Checker: UI API called on a background thread: -[NSView bounds]
-[NSView bounds] must be used from main thread only

I got it to work by following this "trick" where we just turn off the Main Thread Checker. Not sure if it's the ideal solution here though :p

Maybe we should just create a separate UI test for these kind of functions?

This issue is resolved in VLC master and VLC 3.0. Please update your libvlc check-out :)