feat(telemetry): implement CoreAudio audio devices telemetry provider (fixes #21 )

2026-09-08 12:49:57 +01:00
5 changed files with 371 additions and 0 deletions
@@ -36,6 +36,7 @@
 		951DBA5D3BBAB753322A5DF9 /* MMLoadAverageProvider.m in Sources */ = {isa = PBXBuildFile; fileRef = B5F2256DF514DD737306302B /* MMLoadAverageProvider.m */; };
 		9B5C651AD2AF7DE2738F0C44 /* MMPowerTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = D48698681374BD25B980C000 /* MMPowerTests.swift */; };
 		9BCE74C5454F81EF80492E75 /* MacMonitorTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2EC3EDFCD5C50CB352FCED87 /* MacMonitorTests.swift */; };
+		9D12825C7904FB0DAE664CA0 /* MMAudioTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 10D16E1ABE6D28B676EA83FF /* MMAudioTests.swift */; };
 		A521961E035DD50ED8B0C1A9 /* MMKernelTelemetryProvider.m in Sources */ = {isa = PBXBuildFile; fileRef = F444F4543F0A7421C8F8E636 /* MMKernelTelemetryProvider.m */; };
 		A599E974E56F0B8D94A7E480 /* MMNetworkSocketsProvider.m in Sources */ = {isa = PBXBuildFile; fileRef = D78F76C1996D7FCA241CE532 /* MMNetworkSocketsProvider.m */; };
 		A7609CE56D49EC3419987468 /* SystemTelemetryStore.swift in Sources */ = {isa = PBXBuildFile; fileRef = E4B4E94FB2886C60D5548A2A /* SystemTelemetryStore.swift */; };
@@ -45,6 +46,7 @@
 		B9C2D6574E808B517BA34C83 /* MMMemoryTelemetryProvider.m in Sources */ = {isa = PBXBuildFile; fileRef = 991AEEAF262F3C6BE930BC77 /* MMMemoryTelemetryProvider.m */; };
 		BC487DB86227F09CB0603894 /* MMBatteryTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = B0EB61D811D989279BCBE478 /* MMBatteryTests.swift */; };
 		CD91FC663B19DA1FEA3D49D7 /* MMAppleSMCClient.m in Sources */ = {isa = PBXBuildFile; fileRef = 5555436CD3CB8A73F5D6504F /* MMAppleSMCClient.m */; };
+		D7784A61FE4635275CFB3D6C /* MMAudioTelemetryProvider.m in Sources */ = {isa = PBXBuildFile; fileRef = 3189D2403E6E984D4924AE4D /* MMAudioTelemetryProvider.m */; };
 		E3CCE93A7D4D1EB0187D3E52 /* MMNetworkBandwidthProvider.m in Sources */ = {isa = PBXBuildFile; fileRef = C539AEA27C794C6F428EA875 /* MMNetworkBandwidthProvider.m */; };
 		E6F2F695B8D3E7045967C082 /* MMFanTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 336CEE35A745F3C7E9F70F43 /* MMFanTests.swift */; };
 		EAFAF5A10502D4ACC64F4720 /* MMTelemetryCoordinator.m in Sources */ = {isa = PBXBuildFile; fileRef = F9F9AD1268F906761032AF4D /* MMTelemetryCoordinator.m */; };
@@ -71,6 +73,7 @@
 		099DCF7EF03A58ADA40A94A1 /* MMMemoryTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MMMemoryTests.swift; sourceTree = "<group>"; };
 		0C94CCFBE8C9E1370368A28C /* MMNetworkSocketsProvider.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = MMNetworkSocketsProvider.h; sourceTree = "<group>"; };
 		0F2BD3777A674DC4EB442890 /* MMCPUThermalTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MMCPUThermalTests.swift; sourceTree = "<group>"; };
+		10D16E1ABE6D28B676EA83FF /* MMAudioTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MMAudioTests.swift; sourceTree = "<group>"; };
 		1AD9EEE571CD904BBCD1C96B /* MMSMCParser.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = MMSMCParser.h; sourceTree = "<group>"; };
 		1B07A683AD0EFBA8E1FB6C9D /* MMProcessDetailInspector.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = MMProcessDetailInspector.h; sourceTree = "<group>"; };
 		2345555FF9780B02A90CC7A9 /* CoreFoundation.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = CoreFoundation.framework; path = System/Library/Frameworks/CoreFoundation.framework; sourceTree = SDKROOT; };
@@ -79,6 +82,7 @@
 		2DC6E55C9D3F646A1C62133D /* MMBatteryTelemetryProvider.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = MMBatteryTelemetryProvider.h; sourceTree = "<group>"; };
 		2E6A10A13A49E22E51862895 /* MMPeripheralsProvider.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = MMPeripheralsProvider.m; sourceTree = "<group>"; };
 		2EC3EDFCD5C50CB352FCED87 /* MacMonitorTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MacMonitorTests.swift; sourceTree = "<group>"; };
+		3189D2403E6E984D4924AE4D /* MMAudioTelemetryProvider.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = MMAudioTelemetryProvider.m; sourceTree = "<group>"; };
 		32340166F6100A08105308D3 /* MMTelemetryCoordinator.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = MMTelemetryCoordinator.h; sourceTree = "<group>"; };
 		336CEE35A745F3C7E9F70F43 /* MMFanTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MMFanTests.swift; sourceTree = "<group>"; };
 		374B1BF631CC4738CB52CA3B /* MMNetworkSocketsTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MMNetworkSocketsTests.swift; sourceTree = "<group>"; };
@@ -95,6 +99,7 @@
 		5635101F862DE680856BDE6E /* MMTelemetryDomain.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = MMTelemetryDomain.h; sourceTree = "<group>"; };
 		56E285A0A1746AE659981F22 /* MacMonitorTests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = MacMonitorTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		57845310A3D4EC67E48A3B11 /* MMCPULoadProvider.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = MMCPULoadProvider.h; sourceTree = "<group>"; };
+		5C45D1EB09E045A53A154136 /* MMAudioTelemetryProvider.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = MMAudioTelemetryProvider.h; sourceTree = "<group>"; };
 		62C377EFD025D6A6B5563E77 /* MMCPUThermalProvider.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = MMCPUThermalProvider.m; sourceTree = "<group>"; };
 		6D0E5CAF25DFA9A1D2A698A0 /* MMTelemetryProvider.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = MMTelemetryProvider.h; sourceTree = "<group>"; };
 		6DCBCEA450103E2404761B78 /* MMStorageTelemetryProvider.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = MMStorageTelemetryProvider.m; sourceTree = "<group>"; };
@@ -241,6 +246,7 @@
 		8BF79E3BCB76E7A1669DC930 /* Telemetry */ = {
 			isa = PBXGroup;
 			children = (
+				92E1EF545807CF318620FEAA /* Audio */,
 				78383CED205BCA772701AE48 /* CPU */,
 				AD2995435E44FA3E1790A4F3 /* Fan */,
 				F99AF003017BA9F19F7AEB1E /* GPU */,
@@ -268,6 +274,15 @@
 			path = Network;
 			sourceTree = "<group>";
 		};
+		92E1EF545807CF318620FEAA /* Audio */ = {
+			isa = PBXGroup;
+			children = (
+				5C45D1EB09E045A53A154136 /* MMAudioTelemetryProvider.h */,
+				3189D2403E6E984D4924AE4D /* MMAudioTelemetryProvider.m */,
+			);
+			path = Audio;
+			sourceTree = "<group>";
+		};
 		9844EC526E3527F6A582179F /* Hardware */ = {
 			isa = PBXGroup;
 			children = (
@@ -318,6 +333,7 @@
 			isa = PBXGroup;
 			children = (
 				2EC3EDFCD5C50CB352FCED87 /* MacMonitorTests.swift */,
+				10D16E1ABE6D28B676EA83FF /* MMAudioTests.swift */,
 				B0EB61D811D989279BCBE478 /* MMBatteryTests.swift */,
 				B288C7402E2C00E75F8CD016 /* MMComponentThermalTests.swift */,
 				4CE92B1A8D7FDBB6499448E1 /* MMCPULoadTests.swift */,
@@ -474,6 +490,7 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				9D12825C7904FB0DAE664CA0 /* MMAudioTests.swift in Sources */,
 				BC487DB86227F09CB0603894 /* MMBatteryTests.swift in Sources */,
 				160334CC765E091A7CBE21AA /* MMCPULoadTests.swift in Sources */,
 				87818E46CEA5145A8215D0E3 /* MMCPUThermalTests.swift in Sources */,
@@ -502,6 +519,7 @@
 			files = (
 				A9FCAEC0BF27A419DB148C4A /* ContentView.swift in Sources */,
 				CD91FC663B19DA1FEA3D49D7 /* MMAppleSMCClient.m in Sources */,
+				D7784A61FE4635275CFB3D6C /* MMAudioTelemetryProvider.m in Sources */,
 				8EDDC2171C55B6E7FC999DAB /* MMBatteryTelemetryProvider.m in Sources */,
 				4419FE7554489B23976E2970 /* MMCPULoadProvider.m in Sources */,
 				87A9E18362486D0D385BBC4A /* MMCPUThermalProvider.m in Sources */,
@@ -29,5 +29,6 @@
 #import "MMGPUTelemetryProvider.h"
 #import "MMBatteryTelemetryProvider.h"
 #import "MMPeripheralsProvider.h"
+#import "MMAudioTelemetryProvider.h"

 #endif /* MacMonitor_Bridging_Header_h */
@@ -0,0 +1,40 @@
+//
+//  MMAudioTelemetryProvider.h
+//  MacMonitor
+//
+//  Telemetry provider enumerating CoreAudio input/output devices, sample rates, volume, and active status.
+//
+
+#import <Foundation/Foundation.h>
+#import "MMTelemetryProvider.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface MMAudioDevice : NSObject
+
+@property (nonatomic, assign) uint32_t deviceID;
+@property (nonatomic, copy) NSString *name;
+@property (nonatomic, copy) NSString *manufacturer;
+@property (nonatomic, copy) NSString *uid;
+@property (nonatomic, assign) BOOL isInput;
+@property (nonatomic, assign) BOOL isOutput;
+@property (nonatomic, assign) BOOL isDefaultInput;
+@property (nonatomic, assign) BOOL isDefaultOutput;
+@property (nonatomic, assign) double sampleRate;
+@property (nonatomic, assign) uint32_t channelCount;
+@property (nonatomic, assign) float volume;
+@property (nonatomic, assign) BOOL isMuted;
+
+- (NSDictionary<NSString *, id> *)toDictionary;
+
+@end
+
+@interface MMAudioTelemetryProvider : NSObject <MMTelemetryProvider>
+
+- (instancetype)init;
+
+ (NSArray<MMAudioDevice *> *)sampleAudioDevices;
+
+@end
+
+NS_ASSUME_NONNULL_END
@@ -0,0 +1,232 @@
+//
+//  MMAudioTelemetryProvider.m
+//  MacMonitor
+//
+//  Telemetry provider enumerating CoreAudio input/output devices, sample rates, volume, and active status.
+//
+
+#import "MMAudioTelemetryProvider.h"
+#import <CoreAudio/CoreAudio.h>
+
+@implementation MMAudioDevice
+
+- (NSDictionary<NSString *, id> *)toDictionary {
+    return @{
+        @"deviceID": @(self.deviceID),
+        @"name": self.name ?: @"Unknown Audio Device",
+        @"manufacturer": self.manufacturer ?: @"Unknown",
+        @"uid": self.uid ?: @"",
+        @"isInput": @(self.isInput),
+        @"isOutput": @(self.isOutput),
+        @"isDefaultInput": @(self.isDefaultInput),
+        @"isDefaultOutput": @(self.isDefaultOutput),
+        @"sampleRate": @(self.sampleRate),
+        @"channelCount": @(self.channelCount),
+        @"volume": @(roundf(self.volume * 100.0f) / 100.0f),
+        @"isMuted": @(self.isMuted)
+    };
+}
+
+@end
+
+@implementation MMAudioTelemetryProvider
+
+- (instancetype)init {
+    self = [super init];
+    return self;
+}
+
+- (MMTelemetryDomain)domain {
+    return MMTelemetryDomainAudio;
+}
+
+- (NSString *)providerIdentifier {
+    return @"com.i3omb.macmonitor.telemetry.audio";
+}
+
+- (BOOL)isAvailable {
+    return YES;
+}
+
+ (AudioDeviceID)defaultDeviceForProperty:(AudioObjectPropertySelector)selector {
+    AudioObjectPropertyAddress address = {
+        .mSelector = selector,
+        .mScope = kAudioObjectPropertyScopeGlobal,
+        .mElement = kAudioObjectPropertyElementMain
+    };
+    AudioDeviceID deviceID = kAudioObjectUnknown;
+    UInt32 size = sizeof(AudioDeviceID);
+    OSStatus status = AudioObjectGetPropertyData(kAudioObjectSystemObject, &address, 0, NULL, &size, &deviceID);
+    if (status == noErr) {
+        return deviceID;
+    }
+    return kAudioObjectUnknown;
+}
+
+ (NSArray<MMAudioDevice *> *)sampleAudioDevices {
+    AudioObjectPropertyAddress address = {
+        .mSelector = kAudioHardwarePropertyDevices,
+        .mScope = kAudioObjectPropertyScopeGlobal,
+        .mElement = kAudioObjectPropertyElementMain
+    };
+    
+    UInt32 dataSize = 0;
+    OSStatus status = AudioObjectGetPropertyDataSize(kAudioObjectSystemObject, &address, 0, NULL, &dataSize);
+    if (status != noErr || dataSize == 0) {
+        return @[];
+    }
+    
+    UInt32 deviceCount = dataSize / sizeof(AudioDeviceID);
+    AudioDeviceID *deviceIDs = (AudioDeviceID *)malloc(dataSize);
+    if (!deviceIDs) return @[];
+    
+    status = AudioObjectGetPropertyData(kAudioObjectSystemObject, &address, 0, NULL, &dataSize, deviceIDs);
+    if (status != noErr) {
+        free(deviceIDs);
+        return @[];
+    }
+    
+    AudioDeviceID defaultIn = [self defaultDeviceForProperty:kAudioHardwarePropertyDefaultInputDevice];
+    AudioDeviceID defaultOut = [self defaultDeviceForProperty:kAudioHardwarePropertyDefaultOutputDevice];
+    
+    NSMutableArray<MMAudioDevice *> *devices = [NSMutableArray arrayWithCapacity:deviceCount];
+    
+    for (UInt32 i = 0; i < deviceCount; i++) {
+        AudioDeviceID devID = deviceIDs[i];
+        
+        // Name
+        CFStringRef nameRef = NULL;
+        UInt32 propSize = sizeof(CFStringRef);
+        AudioObjectPropertyAddress nameAddr = {
+            .mSelector = kAudioObjectPropertyName,
+            .mScope = kAudioObjectPropertyScopeGlobal,
+            .mElement = kAudioObjectPropertyElementMain
+        };
+        NSString *name = @"Audio Device";
+        if (AudioObjectGetPropertyData(devID, &nameAddr, 0, NULL, &propSize, &nameRef) == noErr && nameRef) {
+            name = (__bridge_transfer NSString *)nameRef;
+        }
+        
+        // Manufacturer
+        CFStringRef mfrRef = NULL;
+        propSize = sizeof(CFStringRef);
+        AudioObjectPropertyAddress mfrAddr = {
+            .mSelector = kAudioObjectPropertyManufacturer,
+            .mScope = kAudioObjectPropertyScopeGlobal,
+            .mElement = kAudioObjectPropertyElementMain
+        };
+        NSString *mfr = @"Apple Inc.";
+        if (AudioObjectGetPropertyData(devID, &mfrAddr, 0, NULL, &propSize, &mfrRef) == noErr && mfrRef) {
+            mfr = (__bridge_transfer NSString *)mfrRef;
+        }
+        
+        // UID
+        CFStringRef uidRef = NULL;
+        propSize = sizeof(CFStringRef);
+        AudioObjectPropertyAddress uidAddr = {
+            .mSelector = kAudioDevicePropertyDeviceUID,
+            .mScope = kAudioObjectPropertyScopeGlobal,
+            .mElement = kAudioObjectPropertyElementMain
+        };
+        NSString *uid = @"";
+        if (AudioObjectGetPropertyData(devID, &uidAddr, 0, NULL, &propSize, &uidRef) == noErr && uidRef) {
+            uid = (__bridge_transfer NSString *)uidRef;
+        }
+        
+        // Channels & Input / Output determination
+        AudioObjectPropertyAddress inputStreamsAddr = {
+            .mSelector = kAudioDevicePropertyStreams,
+            .mScope = kAudioDevicePropertyScopeInput,
+            .mElement = kAudioObjectPropertyElementMain
+        };
+        UInt32 inStreamSize = 0;
+        AudioObjectGetPropertyDataSize(devID, &inputStreamsAddr, 0, NULL, &inStreamSize);
+        BOOL isInput = (inStreamSize > 0);
+        
+        AudioObjectPropertyAddress outputStreamsAddr = {
+            .mSelector = kAudioDevicePropertyStreams,
+            .mScope = kAudioDevicePropertyScopeOutput,
+            .mElement = kAudioObjectPropertyElementMain
+        };
+        UInt32 outStreamSize = 0;
+        AudioObjectGetPropertyDataSize(devID, &outputStreamsAddr, 0, NULL, &outStreamSize);
+        BOOL isOutput = (outStreamSize > 0);
+        
+        // Sample rate
+        Float64 sampleRate = 0.0;
+        propSize = sizeof(Float64);
+        AudioObjectPropertyAddress rateAddr = {
+            .mSelector = kAudioDevicePropertyNominalSampleRate,
+            .mScope = kAudioObjectPropertyScopeGlobal,
+            .mElement = kAudioObjectPropertyElementMain
+        };
+        AudioObjectGetPropertyData(devID, &rateAddr, 0, NULL, &propSize, &sampleRate);
+        
+        // Volume
+        Float32 volume = 0.0f;
+        AudioObjectPropertyScope volScope = isOutput ? kAudioDevicePropertyScopeOutput : kAudioDevicePropertyScopeInput;
+        AudioObjectPropertyAddress volAddr = {
+            .mSelector = kAudioDevicePropertyVolumeScalar,
+            .mScope = volScope,
+            .mElement = kAudioObjectPropertyElementMain
+        };
+        propSize = sizeof(Float32);
+        if (AudioObjectHasProperty(devID, &volAddr)) {
+            AudioObjectGetPropertyData(devID, &volAddr, 0, NULL, &propSize, &volume);
+        }
+        
+        // Mute status
+        UInt32 mute = 0;
+        AudioObjectPropertyAddress muteAddr = {
+            .mSelector = kAudioDevicePropertyMute,
+            .mScope = volScope,
+            .mElement = kAudioObjectPropertyElementMain
+        };
+        propSize = sizeof(UInt32);
+        if (AudioObjectHasProperty(devID, &muteAddr)) {
+            AudioObjectGetPropertyData(devID, &muteAddr, 0, NULL, &propSize, &mute);
+        }
+        
+        MMAudioDevice *device = [[MMAudioDevice alloc] init];
+        device.deviceID = devID;
+        device.name = name;
+        device.manufacturer = mfr;
+        device.uid = uid;
+        device.isInput = isInput;
+        device.isOutput = isOutput;
+        device.isDefaultInput = (devID == defaultIn);
+        device.isDefaultOutput = (devID == defaultOut);
+        device.sampleRate = (double)sampleRate;
+        device.channelCount = (inStreamSize / sizeof(AudioStreamID)) + (outStreamSize / sizeof(AudioStreamID));
+        device.volume = volume;
+        device.isMuted = (mute != 0);
+        
+        [devices addObject:device];
+    }
+    
+    free(deviceIDs);
+    return devices;
+}
+
+- (nullable NSDictionary<NSString *, id> *)sampleTelemetryWithError:(NSError **)error {
+    NSArray<MMAudioDevice *> *devices = [MMAudioTelemetryProvider sampleAudioDevices];
+    NSMutableArray<NSDictionary<NSString *, id> *> *deviceList = [NSMutableArray arrayWithCapacity:devices.count];
+    
+    MMAudioDevice *defaultIn = nil;
+    MMAudioDevice *defaultOut = nil;
+    
+    for (MMAudioDevice *d in devices) {
+        [deviceList addObject:[d toDictionary]];
+        if (d.isDefaultInput) defaultIn = d;
+        if (d.isDefaultOutput) defaultOut = d;
+    }
+    
+    return @{
+        @"devices": deviceList,
+        @"deviceCount": @(devices.count),
+        @"defaultInputDevice": defaultIn ? [defaultIn toDictionary] : [NSNull null],
+        @"defaultOutputDevice": defaultOut ? [defaultOut toDictionary] : [NSNull null]
+    };
+}
+
+@end
@@ -0,0 +1,80 @@
+//
+//  MMAudioTests.swift
+//  MacMonitorTests
+//
+//  Unit and integration tests for MMAudioTelemetryProvider.
+//
+
+import XCTest
+@testable import MacMonitor
+
+final class MMAudioTests: XCTestCase {
+    var provider: MMAudioTelemetryProvider!
+
+    override func setUp() {
+        super.setUp()
+        provider = MMAudioTelemetryProvider()
+    }
+
+    override func tearDown() {
+        provider = nil
+        super.tearDown()
+    }
+
+    func testDomainAndIdentifier() {
+        XCTAssertEqual(provider.domain, .audio)
+        XCTAssertEqual(provider.providerIdentifier, "com.i3omb.macmonitor.telemetry.audio")
+        XCTAssertTrue(provider.isAvailable)
+    }
+
+    func testSampleAudioDevicesLive() {
+        do {
+            let sample = try provider.sampleTelemetry()
+            XCTAssertNotNil(sample)
+            
+            let count = sample["deviceCount"] as? Int ?? 0
+            XCTAssertGreaterThanOrEqual(count, 0)
+            
+            let devices = sample["devices"] as? [[String: Any]] ?? []
+            XCTAssertEqual(devices.count, count)
+            
+            if count > 0 {
+                for dev in devices {
+                    XCTAssertNotNil(dev["name"])
+                    XCTAssertNotNil(dev["deviceID"])
+                    XCTAssertNotNil(dev["isInput"])
+                    XCTAssertNotNil(dev["isOutput"])
+                }
+            }
+        } catch {
+            XCTFail("sampleTelemetry threw error: \(error)")
+        }
+    }
+
+    func testAudioDeviceModel() {
+        let dev = MMAudioDevice()
+        dev.deviceID = 42
+        dev.name = "External USB DAC"
+        dev.manufacturer = "FiiO"
+        dev.uid = "USB:1234"
+        dev.isInput = false
+        dev.isOutput = true
+        dev.isDefaultOutput = true
+        dev.isDefaultInput = false
+        dev.sampleRate = 96000.0
+        dev.channelCount = 2
+        dev.volume = 0.75
+        dev.isMuted = false
+
+        let dict = dev.toDictionary()
+        XCTAssertEqual(dict["deviceID"] as? UInt32, 42)
+        XCTAssertEqual(dict["name"] as? String, "External USB DAC")
+        XCTAssertEqual(dict["manufacturer"] as? String, "FiiO")
+        XCTAssertEqual(dict["isOutput"] as? Bool, true)
+        XCTAssertEqual(dict["isDefaultOutput"] as? Bool, true)
+        XCTAssertEqual(dict["sampleRate"] as? Double, 96000.0)
+        XCTAssertEqual(dict["channelCount"] as? UInt32, 2)
+        XCTAssertEqual(dict["volume"] as? Float, 0.75)
+        XCTAssertEqual(dict["isMuted"] as? Bool, false)
+    }
+}