Add Swift Testing harness and SwiftUI previews

.github/PULL_REQUEST_TEMPLATE.md

@@ -7,4 +7,5 @@
 
 ## Checklist
 - [ ] Builds without errors (`xcodegen generate && xcodebuild -scheme ChillMac build`)
+- [ ] Unit tests pass (`xcodebuild -project ChillMac.xcodeproj -scheme ChillMac -destination 'platform=macOS' test`)
 - [ ] Tested manually in the app

AGENTS.md

@@ -93,6 +93,7 @@ ChillMac/
     BatteryInfo       Battery info via IOKit/IOPowerSources (polls every 5s)
   SMC/              - IOKit bridge (SMCConnection, SMCTypes, SMCKeys)
   XPC/              - HelperConnection (client), HelperInstaller
+  Preview/          - PreviewSupport factories for SwiftUI canvas + tests (#if DEBUG)
 FanControlHelper/
   main.swift        - Helper daemon entry point
   HelperDelegate.swift - XPC listener + code signature validation
@@ -123,6 +124,16 @@ scripts/
 - 420x640 main popover, 370x560 detail panels
 - Footer with quit button, app name, and °F/°C toggle
 
-## No Tests
+## Testing
 
-There is no test suite. Testing is done manually via the UI.
+Unit tests live in `ChillMacTests` (Swift Testing). Run:
+
+```bash
+xcodegen generate && xcodebuild -project ChillMac.xcodeproj -scheme ChillMac -destination 'platform=macOS' test
+```
+
+- Use `@Test` / `#expect` / `@Suite` (Swift Testing only — no XCTest UI suite yet)
+- Sample data for fixtures and canvas comes from `ChillMac/Preview/PreviewSupport.swift` — do not hit live SMC/XPC in unit tests or invent local sample data in views
+- SwiftUI convention: add in-file `#Preview("…")` (plain macros, no traits) wired to `PreviewSupport` factories; keep `#Preview` under `#if DEBUG`
+- Zero external test dependencies (no ViewInspector, no snapshot libs)
+- Test plan: `TestPlans/Unit.xctestplan`

CLAUDE.md

@@ -93,6 +93,7 @@ ChillMac/
     BatteryInfo       Battery info via IOKit/IOPowerSources (polls every 5s)
   SMC/              - IOKit bridge (SMCConnection, SMCTypes, SMCKeys)
   XPC/              - HelperConnection (client), HelperInstaller
+  Preview/          - PreviewSupport factories for SwiftUI canvas + tests (#if DEBUG)
 FanControlHelper/
   main.swift        - Helper daemon entry point
   HelperDelegate.swift - XPC listener + code signature validation
@@ -123,6 +124,16 @@ scripts/
 - 420x640 main popover, 370x560 detail panels
 - Footer with quit button, app name, and °F/°C toggle
 
-## No Tests
+## Testing
 
-There is no test suite. Testing is done manually via the UI.
+Unit tests live in `ChillMacTests` (Swift Testing). Run:
+
+```bash
+xcodegen generate && xcodebuild -project ChillMac.xcodeproj -scheme ChillMac -destination 'platform=macOS' test
+```
+
+- Use `@Test` / `#expect` / `@Suite` (Swift Testing only — no XCTest UI suite yet)
+- Sample data for fixtures and canvas comes from `ChillMac/Preview/PreviewSupport.swift` — do not hit live SMC/XPC in unit tests or invent local sample data in views
+- SwiftUI convention: add in-file `#Preview("…")` (plain macros, no traits) wired to `PreviewSupport` factories; keep `#Preview` under `#if DEBUG`
+- Zero external test dependencies (no ViewInspector, no snapshot libs)
+- Test plan: `TestPlans/Unit.xctestplan`

CONTRIBUTING.md

@@ -24,7 +24,7 @@ Debug builds skip the helper's code signature check, so you don't need a Develop
 1. Fork the repo and create a branch from `main`
 2. Make your changes
 3. Make sure it builds: `xcodegen generate && xcodebuild -scheme ChillMac build`
-4. Test manually — there's no automated test suite
+4. Run unit tests: `xcodebuild -project ChillMac.xcodeproj -scheme ChillMac -destination 'platform=macOS' test`
 5. Open a PR
 
 ## Project Overview
@@ -40,7 +40,8 @@ Debug builds skip the helper's code signature check, so you don't need a Develop
 - Match the existing code style (no linter configured, just stay consistent)
 - SwiftUI views go in `ChillMac/Views/`
 - New monitors/data models go in `ChillMac/Fan/`
-- The app has zero external dependencies — let's keep it that way unless there's a strong reason
+- Use `PreviewSupport` for sample data; add in-file `#Preview` (no live SMC/XPC in canvas)
+- The app has zero external dependencies — let's keep it that way unless there's a strong reason (Swift Testing only; no third-party test libs)
 
 ## Architecture Notes
 

ChillMac/App/DetailPanelController.swift

@@ -166,3 +166,13 @@ struct DetailPanelCloseButton: View {
         .buttonStyle(.plain)
     }
 }
+
+#if DEBUG
+#Preview("Detail Panel Close Button") {
+    return PreviewSupport.previewHost(theme: .dark, frame: .detail) {
+        DetailPanelCloseButton(action: {})
+            .padding()
+    }
+}
+#endif
+

ChillMac/App/Theme.swift

@@ -102,3 +102,14 @@ struct ThemedView<Content: View>: View {
             .preferredColorScheme(settings.preferredColorScheme)
     }
 }
+
+#if DEBUG
+#Preview("ThemedView") {
+    return ThemedView(content:
+        Text("Sample")
+            .padding(20)
+    )
+    .frame(width: 200, height: 100)
+}
+#endif
+

ChillMac/Fan/SystemInfo.swift

@@ -59,6 +59,31 @@ final class SystemInfo: ObservableObject {
         refreshDynamic()
     }
 
+    #if DEBUG
+    /// Canned sample for previews/tests — skips `fetchHardwareInfo()` and timers.
+    static var previewSample: SystemInfo {
+        SystemInfo(previewSample: ())
+    }
+
+    private init(previewSample: Void) {
+        machineModel = "MacBook Pro"
+        chipName = "Apple M3 Pro"
+        ramAmount = "36 GB"
+        macOSVersion = "macOS 15.0.0"
+        diskUsage = "256 GB"
+        uptime = "2d 5h 12m"
+        diskTotalBytes = 512_110_190_592
+        diskAvailableBytes = 275_146_342_400
+        diskCategories = [
+            DiskCategory(name: "Applications", bytes: 45_000_000_000, color: .systemRed),
+            DiskCategory(name: "Downloads", bytes: 12_000_000_000, color: .systemPink),
+            DiskCategory(name: "Documents", bytes: 28_000_000_000, color: .systemBlue),
+            DiskCategory(name: "Desktop", bytes: 4_000_000_000, color: .systemGreen),
+            DiskCategory(name: "Other", bytes: 148_000_000_000, color: .systemGray),
+        ]
+    }
+    #endif
+
     func startMonitoring() {
         guard timer == nil else { return }
         refreshDynamic()

ChillMac/Preview/PreviewSupport.swift

@@ -0,0 +1,179 @@
+#if DEBUG
+import SwiftUI
+
+/// Shared sample data for SwiftUI `#Preview` and unit tests.
+/// Factories construct and seed only — never start monitors, XPC, or network.
+enum PreviewSupport {
+    // MARK: - Sample values
+
+    static let sampleFans: [FanInfo] = [
+        FanInfo(
+            id: 0,
+            name: "Left Fan",
+            currentRPM: 2800,
+            minRPM: 1200,
+            maxRPM: 6000,
+            targetRPM: 2800,
+            isManualMode: false
+        ),
+        FanInfo(
+            id: 1,
+            name: "Right Fan",
+            currentRPM: 2650,
+            minRPM: 1200,
+            maxRPM: 6000,
+            targetRPM: 2650,
+            isManualMode: true
+        ),
+    ]
+
+    static let sampleSensors: [TemperatureSensor] = [
+        TemperatureSensor(id: "Tp09", label: "CPU Die", temperature: 58.5),
+        TemperatureSensor(id: "TG0P", label: "GPU", temperature: 52.0),
+        TemperatureSensor(id: "TH0x", label: "SSD", temperature: 41.2),
+        TemperatureSensor(id: "TB0T", label: "Battery", temperature: 33.8),
+    ]
+
+    private static let sampleCpuHistory: [Double] = [
+        12, 18, 22, 35, 48, 42, 38, 55, 62, 58,
+        45, 40, 33, 28, 25, 30, 44, 50, 47, 36,
+        28, 22, 18, 15,
+    ]
+
+    // MARK: - Factories
+
+    static var fanMonitor: FanMonitor {
+        let monitor = FanMonitor()
+        monitor.helperReady = true
+        monitor.fans = sampleFans
+        monitor.sensors = sampleSensors
+        monitor.peakTemperature = 58.5
+        monitor.peakTemperatureLabel = "CPU Die"
+        monitor.peakCpuTemperature = 58.5
+        monitor.peakGpuTemperature = 52.0
+        monitor.peakSsdTemperature = 41.2
+        return monitor
+    }
+
+    /// Fan monitor seeded like Performance Mode Max under load (matches expanded Fans card).
+    static var fanMonitorPerformanceActive: FanMonitor {
+        let monitor = fanMonitor
+        monitor.peakTemperature = 92.2
+        monitor.peakTemperatureLabel = "CPU Die"
+        monitor.peakCpuTemperature = 92.2
+        monitor.performanceCurvePercent = 100
+        return monitor
+    }
+
+    /// Posts the same notification StatusBarController sends when the popover opens,
+    /// so `@State appeared` fades content in during canvas previews.
+    static func triggerPopoverAppeared() {
+        NotificationCenter.default.post(name: .popoverDidShow, object: nil)
+    }
+
+    static var cpuInfo: CpuInfo {
+        let info = CpuInfo()
+        info.userPercent = 28
+        info.systemPercent = 12
+        info.idlePercent = 60
+        info.totalUsage = 40
+        info.history = sampleCpuHistory
+        info.userHistory = sampleCpuHistory.map { $0 * 0.7 }
+        info.systemHistory = sampleCpuHistory.map { $0 * 0.3 }
+        info.topProcesses = [
+            .init(name: "Xcode", cpuPercent: 42.5, icon: nil),
+            .init(name: "Safari", cpuPercent: 18.2, icon: nil),
+            .init(name: "Finder", cpuPercent: 4.1, icon: nil),
+        ]
+        return info
+    }
+
+    static var memoryInfo: MemoryInfo {
+        let info = MemoryInfo()
+        let total = info.totalMemory
+        info.activeMemory = UInt64(Double(total) * 0.35)
+        info.wiredMemory = UInt64(Double(total) * 0.15)
+        info.compressedMemory = UInt64(Double(total) * 0.10)
+        info.availableMemory = total - info.activeMemory - info.wiredMemory - info.compressedMemory
+        info.pressurePercent = 60
+        info.swapUsed = 512 * 1_048_576
+        info.topProcesses = [
+            .init(name: "Xcode", memoryBytes: 2_147_483_648, icon: nil),
+            .init(name: "Safari", memoryBytes: 805_306_368, icon: nil),
+            .init(name: "Finder", memoryBytes: 268_435_456, icon: nil),
+        ]
+        return info
+    }
+
+    static var batteryInfo: BatteryInfo {
+        let info = BatteryInfo()
+        info.currentCharge = 72
+        info.maxCapacity = 4800
+        info.designCapacity = 5200
+        info.cycleCount = 312
+        info.healthPercent = 92
+        info.temperature = 31.5
+        info.isCharging = false
+        info.isPluggedIn = true
+        info.timeRemaining = "4h 22m"
+        info.condition = "Normal"
+        return info
+    }
+
+    static var systemInfo: SystemInfo {
+        SystemInfo.previewSample
+    }
+
+    static var fpsMonitor: DisplayFPSMonitor {
+        let monitor = DisplayFPSMonitor()
+        monitor.fps = 120
+        return monitor
+    }
+
+    static var updateChecker: UpdateChecker {
+        let checker = UpdateChecker()
+        checker.hasChecked = true
+        checker.updateAvailable = false
+        checker.latestVersion = checker.currentVersion
+        return checker
+    }
+
+    static var helper: HelperConnection {
+        HelperConnection()
+    }
+
+    // MARK: - Preview chrome
+
+    enum PreviewFrame {
+        case popover
+        case detail
+    }
+
+    static func previewHost<Content: View>(
+        theme: AppTheme = .dark,
+        frame: PreviewFrame = .popover,
+        @ViewBuilder content: () -> Content
+    ) -> some View {
+        let size: CGSize = {
+            switch frame {
+            case .popover: return CGSize(width: 420, height: 640)
+            case .detail: return CGSize(width: 360, height: 560)
+            }
+        }()
+        return content()
+            .environment(\.theme, theme)
+            .preferredColorScheme(themeIsDark(theme) ? .dark : .light)
+            .frame(width: size.width, height: size.height)
+    }
+
+    private static func themeIsDark(_ theme: AppTheme) -> Bool {
+        theme.bgGradientTop == AppTheme.dark.bgGradientTop
+    }
+}
+
+extension View {
+    func previewHost(theme: AppTheme = .dark, frame: PreviewSupport.PreviewFrame = .popover) -> some View {
+        PreviewSupport.previewHost(theme: theme, frame: frame) { self }
+    }
+}
+#endif

ChillMac/Views/BatteryDetailView.swift

@@ -262,3 +262,28 @@ private struct BatteryDetailRow: View {
         .padding(.vertical, 8)
     }
 }
+
+#if DEBUG
+#Preview("Battery Detail — Dark") {
+    BatteryDetailView(
+        batteryInfo: PreviewSupport.batteryInfo,
+        settings: AppSettings.shared
+    )
+    .previewHost(theme: .dark, frame: .detail)
+}
+
+#Preview("Battery Detail — Light") {
+    BatteryDetailView(
+        batteryInfo: PreviewSupport.batteryInfo,
+        settings: AppSettings.shared
+    )
+    .previewHost(theme: .light, frame: .detail)
+}
+
+#Preview("Battery Detail Row") {
+    let info = PreviewSupport.batteryInfo
+    return BatteryDetailRow(label: "Condition", value: info.condition)
+        .padding()
+        .previewHost(theme: .dark, frame: .detail)
+}
+#endif

ChillMac/Views/CpuDetailView.swift

@@ -367,3 +367,46 @@ struct CpuGraphView: View {
         }
     }
 }
+
+#if DEBUG
+#Preview("CpuDetailView Dark") {
+    CpuDetailView(
+        cpuInfo: PreviewSupport.cpuInfo,
+        systemInfo: PreviewSupport.systemInfo,
+        monitor: PreviewSupport.fanMonitor,
+        settings: AppSettings.shared
+    )
+    .previewHost(theme: .dark, frame: .detail)
+}
+
+#Preview("CpuDetailView Light") {
+    CpuDetailView(
+        cpuInfo: PreviewSupport.cpuInfo,
+        systemInfo: PreviewSupport.systemInfo,
+        monitor: PreviewSupport.fanMonitor,
+        settings: AppSettings.shared
+    )
+    .previewHost(theme: .light, frame: .detail)
+}
+
+#Preview("CpuGraphView") {
+    let cpu = PreviewSupport.cpuInfo
+    return CpuGraphView(
+        history: cpu.history,
+        userHistory: cpu.userHistory,
+        systemHistory: cpu.systemHistory
+    )
+    .previewHost(theme: .dark, frame: .detail)
+}
+
+#Preview("UsageRow") {
+    let cpu = PreviewSupport.cpuInfo
+    return UsageRow(
+        color: .teal,
+        value: String(format: "%.1f %%", 100 - cpu.totalUsage),
+        label: "Available"
+    )
+    .padding()
+    .previewHost(theme: .dark, frame: .detail)
+}
+#endif