mixboard/Tests/Helpers/TestHelpers.swift

import AVFoundation
import Foundation

/// Helpers for creating test audio files and SwiftData contexts.
enum TestHelpers {

    /// Create a short sine wave WAV file for testing.
    static func createTestAudioFile(
        name: String = "test_audio",
        duration: TimeInterval = 2.0,
        sampleRate: Double = 44100,
        frequency: Double = 440,
        in directory: URL? = nil
    ) throws -> URL {
        let dir = directory ?? FileManager.default.temporaryDirectory
            .appendingPathComponent("MixBoardTests/\(UUID().uuidString)", isDirectory: true)
        try FileManager.default.createDirectory(at: dir, withIntermediateDirectories: true)

        let url = dir.appendingPathComponent("\(name)_\(UUID().uuidString.prefix(8)).wav")

        let channels: AVAudioChannelCount = 2

        // Use standard format which AVAudioFile handles correctly
        guard let format = AVAudioFormat(standardFormatWithSampleRate: sampleRate, channels: channels) else {
            throw NSError(domain: "TestHelpers", code: 1, userInfo: [NSLocalizedDescriptionKey: "Failed to create format"])
        }

        let file = try AVAudioFile(forWriting: url, settings: format.settings)
        let frameCount = AVAudioFrameCount(duration * sampleRate)

        guard let buffer = AVAudioPCMBuffer(pcmFormat: file.processingFormat, frameCapacity: frameCount) else {
            throw NSError(domain: "TestHelpers", code: 1, userInfo: [NSLocalizedDescriptionKey: "Failed to create buffer"])
        }

        buffer.frameLength = frameCount

        if let channelData = buffer.floatChannelData {
            for frame in 0..<Int(frameCount) {
                let value = Float(sin(2.0 * .pi * frequency * Double(frame) / sampleRate))
                for ch in 0..<Int(channels) {
                    channelData[ch][frame] = value * 0.5
                }
            }
        }

        try file.write(from: buffer)
        return url
    }

    /// Create multiple test audio files with different "metadata".
    static func createTestAudioFiles(count: Int, duration: TimeInterval = 1.0) throws -> [URL] {
        let frequencies = [261.63, 293.66, 329.63, 349.23, 392.00, 440.00, 493.88, 523.25]
        var urls: [URL] = []
        for i in 0..<count {
            let freq = frequencies[i % frequencies.count]
            let url = try createTestAudioFile(
                name: "test_track_\(i + 1)",
                duration: duration,
                frequency: freq
            )
            urls.append(url)
        }
        return urls
    }

    /// Clean up test files.
    static func cleanupTestFiles() {
        let dir = FileManager.default.temporaryDirectory
            .appendingPathComponent("MixBoardTests", isDirectory: true)
        try? FileManager.default.removeItem(at: dir)
    }

    /// Get the test files directory.
    static var testDirectory: URL {
        FileManager.default.temporaryDirectory
            .appendingPathComponent("MixBoardTests", isDirectory: true)
    }
}