Gerätezuordnungen im Client anzeigen

internal/client/application.go

@@ -70,15 +70,23 @@ type Application struct {
 
 // NewApplication creates a new client Application.
 //
-// No configuration is loaded and no network connection is established.
-// Start must be called before the application can be used.
+// The client configuration is loaded immediately. No network connection
+// is established. Start must be called before the application connects to
+// the server or starts the Runtime.
+
 func NewApplication(configFile string) (*Application, error) {
 	if configFile == "" {
 		return nil, fmt.Errorf("configuration file is empty")
 	}
 
+	cfg, err := config.LoadClient(configFile)
+	if err != nil {
+		return nil, fmt.Errorf("load client configuration: %w", err)
+	}
+
 	return &Application{
 		configFile: configFile,
+		config:     cfg,
 	}, nil
 }
 
@@ -203,7 +211,6 @@ func (a *Application) Close() error {
 
 	a.runtime = nil
 	a.client = nil
-	a.config = nil
 	a.devices = nil
 	a.runtimeDone = nil
 
@@ -224,13 +231,10 @@ func (a *Application) Close() error {
 	return firstErr
 }
 
-///////////////////////////////////////////////////////////////////////////////
-// Configuration
-///////////////////////////////////////////////////////////////////////////////
-
 // Config returns a copy of the currently loaded client configuration.
 //
-// It returns nil when the application has not been started.
+// The configuration is available after NewApplication, even when the
+// server connection has not yet been established.
 func (a *Application) Config() *config.ClientConfig {
 	if a == nil {
 		return nil

internal/client/application_test.go

@@ -9,18 +9,68 @@
  * Beschreibung:
  * Tests für die Anwendungsschicht des rs2322tcp-Clients.
  *
- * Die Tests prüfen zunächst den Lebenszyklus der Application, ohne dafür
- * eine echte Serververbindung aufbauen zu müssen.
+ * Die Tests prüfen den Lebenszyklus der Application und die lokale
+ * Konfigurationsverwaltung, ohne dafür eine echte Serververbindung
+ * aufbauen zu müssen.
  *
  * Insbesondere wird sichergestellt, dass eine neu erzeugte Application
- * zunächst keinen laufenden Client und keine laufende Runtime besitzt und
- * dass Close auch vor einem Start sicher verwendet werden kann.
+ * ihre lokale Konfiguration bereits kennt, obwohl noch keine Verbindung
+ * zum Server besteht.
  * ============================================================================
  */
 
 package client
 
-import "testing"
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"git.lang-dieter.de/rs2322tcp/internal/config"
+)
+
+///////////////////////////////////////////////////////////////////////////////
+// Test helpers
+///////////////////////////////////////////////////////////////////////////////
+
+// writeTestConfig creates a temporary client configuration file.
+func writeTestConfig(t *testing.T) string {
+	t.Helper()
+
+	dir := t.TempDir()
+	filename := filepath.Join(dir, "client.json")
+
+	content := `{
+		"server": {
+			"address": "127.0.0.1",
+			"port": 5000
+		},
+		"virtual_port_range": {
+			"first": 100,
+			"last": 199
+		},
+		"virtual_ports": [
+			{
+				"port": "/dev/ttyUSB100",
+				"remote_device": "radio"
+			},
+			{
+				"port": "/dev/ttyUSB101",
+				"remote_device": "rotor"
+			}
+		]
+	}`
+
+	if err := os.WriteFile(
+		filename,
+		[]byte(content),
+		0600,
+	); err != nil {
+		t.Fatalf("write test configuration: %v", err)
+	}
+
+	return filename
+}
 
 ///////////////////////////////////////////////////////////////////////////////
 // NewApplication
@@ -42,11 +92,14 @@ func TestNewApplicationRejectsEmptyConfigFile(t *testing.T) {
 }
 
 // TestNewApplication verifies that a valid configuration-file path creates
-// an application without starting it.
+// an application and loads the local configuration without starting the
+// network connection.
 func TestNewApplication(t *testing.T) {
 	t.Helper()
 
-	application, err := NewApplication("client.json")
+	configFile := writeTestConfig(t)
+
+	application, err := NewApplication(configFile)
 	if err != nil {
 		t.Fatalf("NewApplication: %v", err)
 	}
@@ -59,28 +112,115 @@ func TestNewApplication(t *testing.T) {
 		t.Fatal("new application reports running")
 	}
 
-	if application.Config() != nil {
-		t.Fatal("new application returned a configuration")
+	cfg := application.Config()
+	if cfg == nil {
+		t.Fatal("new application returned no configuration")
+	}
+
+	if len(cfg.VirtualPorts) != 2 {
+		t.Fatalf(
+			"new application returned %d virtual ports, want 2",
+			len(cfg.VirtualPorts),
+		)
+	}
+
+	if cfg.VirtualPorts[0].Port != "/dev/ttyUSB100" {
+		t.Errorf(
+			"virtual port 0 = %q, want %q",
+			cfg.VirtualPorts[0].Port,
+			"/dev/ttyUSB100",
+		)
+	}
+
+	if cfg.VirtualPorts[0].RemoteDevice != "radio" {
+		t.Errorf(
+			"remote device 0 = %q, want %q",
+			cfg.VirtualPorts[0].RemoteDevice,
+			"radio",
+		)
+	}
+
+	if cfg.VirtualPorts[1].Port != "/dev/ttyUSB101" {
+		t.Errorf(
+			"virtual port 1 = %q, want %q",
+			cfg.VirtualPorts[1].Port,
+			"/dev/ttyUSB101",
+		)
+	}
+
+	if cfg.VirtualPorts[1].RemoteDevice != "rotor" {
+		t.Errorf(
+			"remote device 1 = %q, want %q",
+			cfg.VirtualPorts[1].RemoteDevice,
+			"rotor",
+		)
 	}
 
 	if devices := application.Devices(); len(devices) != 0 {
 		t.Fatalf(
-			"new application returned %d devices",
+			"new application returned %d devices, want 0",
 			len(devices),
 		)
 	}
 }
 
+///////////////////////////////////////////////////////////////////////////////
+// Configuration copy
+///////////////////////////////////////////////////////////////////////////////
+
+// TestApplicationConfigReturnsCopy verifies that modifying the returned
+// configuration does not modify the Application's internal configuration.
+func TestApplicationConfigReturnsCopy(t *testing.T) {
+	t.Helper()
+
+	configFile := writeTestConfig(t)
+
+	application, err := NewApplication(configFile)
+	if err != nil {
+		t.Fatalf("NewApplication: %v", err)
+	}
+
+	cfg := application.Config()
+	if cfg == nil {
+		t.Fatal("Config returned nil")
+	}
+
+	cfg.VirtualPorts[0].Port = "/dev/ttyUSB999"
+	cfg.VirtualPorts[0].RemoteDevice = "changed"
+
+	current := application.Config()
+	if current == nil {
+		t.Fatal("second Config returned nil")
+	}
+
+	if current.VirtualPorts[0].Port != "/dev/ttyUSB100" {
+		t.Errorf(
+			"internal port changed to %q",
+			current.VirtualPorts[0].Port,
+		)
+	}
+
+	if current.VirtualPorts[0].RemoteDevice != "radio" {
+		t.Errorf(
+			"internal remote device changed to %q",
+			current.VirtualPorts[0].RemoteDevice,
+		)
+	}
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Close
 ///////////////////////////////////////////////////////////////////////////////
 
 // TestApplicationCloseBeforeStart verifies that Close can safely be called
-// before the application has been started.
+// before the application has been started and that the local configuration
+// remains available.
 func TestApplicationCloseBeforeStart(t *testing.T) {
 	t.Helper()
 
-	application, err := NewApplication("client.json")
+	configFile := writeTestConfig(t)
+
+	application, err := NewApplication(configFile)
 	if err != nil {
 		t.Fatalf("NewApplication: %v", err)
 	}
@@ -92,14 +232,21 @@ func TestApplicationCloseBeforeStart(t *testing.T) {
 	if application.Running() {
 		t.Fatal("application reports running after Close")
 	}
+
+	if cfg := application.Config(); cfg == nil {
+		t.Fatal("configuration was lost after Close")
+	}
 }
 
 // TestApplicationCloseIsIdempotent verifies that Close can be called more
-// than once without producing an error.
+// than once without producing an error and without losing the local
+// configuration.
 func TestApplicationCloseIsIdempotent(t *testing.T) {
 	t.Helper()
 
-	application, err := NewApplication("client.json")
+	configFile := writeTestConfig(t)
+
+	application, err := NewApplication(configFile)
 	if err != nil {
 		t.Fatalf("NewApplication: %v", err)
 	}
@@ -115,6 +262,42 @@ func TestApplicationCloseIsIdempotent(t *testing.T) {
 	if application.Running() {
 		t.Fatal("application reports running after repeated Close")
 	}
+
+	if cfg := application.Config(); cfg == nil {
+		t.Fatal("configuration was lost after repeated Close")
+	}
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Invalid configuration
+///////////////////////////////////////////////////////////////////////////////
+
+// TestNewApplicationRejectsInvalidConfiguration verifies that an invalid
+// configuration file is rejected immediately.
+func TestNewApplicationRejectsInvalidConfiguration(t *testing.T) {
+	t.Helper()
+
+	dir := t.TempDir()
+	filename := filepath.Join(dir, "invalid.json")
+
+	if err := os.WriteFile(
+		filename,
+		[]byte(`{"invalid": true}`),
+		0600,
+	); err != nil {
+		t.Fatalf("write invalid configuration: %v", err)
+	}
+
+	application, err := NewApplication(filename)
+	if err == nil {
+		t.Fatal("NewApplication with invalid configuration returned no error")
+	}
+
+	if application != nil {
+		t.Fatal(
+			"NewApplication with invalid configuration returned an application",
+		)
+	}
 }
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -155,3 +338,7 @@ func TestNilApplication(t *testing.T) {
 		t.Fatal("nil Application returned devices")
 	}
 }
+
+// Keep config imported explicitly so the test documents that the temporary
+// file represents the normal ClientConfig structure.
+var _ config.ClientConfig

internal/gui/app.go

@@ -27,6 +27,10 @@
  * Dabei wird die bestehende technische Client-Anwendung beendet und
  * anschließend vollständig neu gestartet. Dadurch wird die aktuelle
  * client.json erneut geladen.
+ *
+ * Die Gerätezuordnung wird zunächst ausschließlich angezeigt. Änderungen
+ * an der Zuordnung und deren Speicherung werden in einem späteren
+ * Entwicklungsschritt ergänzt.
  * ============================================================================
  */
 package gui
@@ -52,9 +56,10 @@ type App struct {
 
 	clientApplication *client.Application
 
-	statusLabel     *widget.Label
-	errorLabel      *widget.Label
-	reconnectButton *widget.Button
+	statusLabel      *widget.Label
+	errorLabel       *widget.Label
+	reconnectButton  *widget.Button
+	assignmentButton *widget.Button
 }
 
 // NewApp creates the graphical rs2322tcp client application.
@@ -90,6 +95,11 @@ func NewApp(
 		app.reconnect,
 	)
 
+	app.assignmentButton = widget.NewButton(
+		"Gerätezuordnung",
+		app.showAssignments,
+	)
+
 	app.buildContent()
 
 	return app, nil
@@ -106,6 +116,7 @@ func (a *App) buildContent() {
 		title,
 		a.statusLabel,
 		a.errorLabel,
+		a.assignmentButton,
 		a.reconnectButton,
 	)
 
@@ -209,6 +220,98 @@ func (a *App) reconnect() {
 	}()
 }
 
+// showAssignments displays the current local-to-remote device assignments.
+//
+// This first implementation is deliberately read-only. It obtains the
+// configuration and the current server device list from client.Application
+// and converts them through the GUI-independent assignment functions.
+//
+// No configuration is changed or written by this function.
+func (a *App) showAssignments() {
+	if a == nil {
+		return
+	}
+
+	cfg := a.clientApplication.Config()
+	devices := a.clientApplication.Devices()
+
+	assignments := BuildAssignments(cfg, devices)
+	unassigned := UnassignedDevices(cfg, devices)
+
+	content := container.NewVBox(
+		widget.NewLabel("Lokale Zuordnungen"),
+	)
+
+	if len(assignments) == 0 {
+		content.Add(
+			widget.NewLabel("Keine lokalen Zuordnungen vorhanden."),
+		)
+	} else {
+		for _, assignment := range assignments {
+			status := "nicht verfügbar"
+
+			if assignment.Available {
+				status = "verfügbar"
+			}
+
+			content.Add(
+				widget.NewLabel(
+					fmt.Sprintf(
+						"%s  ->  %s  (%s)",
+						assignment.LocalPort,
+						assignment.RemoteDevice,
+						status,
+					),
+				),
+			)
+		}
+	}
+
+	content.Add(widget.NewSeparator())
+	content.Add(
+		widget.NewLabel("Server-Geräte ohne lokale Zuordnung"),
+	)
+
+	if len(unassigned) == 0 {
+		content.Add(
+			widget.NewLabel(
+				"Keine nicht verwendeten Server-Geräte.",
+			),
+		)
+	} else {
+		for _, device := range unassigned {
+			content.Add(
+				widget.NewLabel(
+					fmt.Sprintf(
+						"%s  –  noch nicht verwendet",
+						device.ID,
+					),
+				),
+			)
+		}
+	}
+
+	assignmentWindow := a.fyneApp.NewWindow(
+		"Gerätezuordnung",
+	)
+	assignmentWindow.Resize(fyne.NewSize(650, 450))
+	assignmentWindow.SetContent(
+		container.NewBorder(
+			nil,
+			widget.NewButton(
+				"Schließen",
+				func() {
+					assignmentWindow.Close()
+				},
+			),
+			nil,
+			nil,
+			container.NewVScroll(content),
+		),
+	)
+	assignmentWindow.Show()
+}
+
 // Close closes the technical client application.
 //
 // The Runtime and the server connection are closed before the GUI window

internal/gui/assignment.go

@@ -0,0 +1,167 @@
+/*
+ * ============================================================================
+ * Projekt.....: rs2322tcp
+ * Datei.......: internal/gui/assignment.go
+ * Copyright (C) 2026 Dieter Lang
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ * Beschreibung:
+ * GUI-unabhängige Aufbereitung der Zuordnung zwischen lokalen virtuellen
+ * seriellen Schnittstellen und den vom rs2322tcp-Server angebotenen Geräten.
+ *
+ * Die Datei enthält bewusst keine Fyne-Abhängigkeiten.
+ *
+ * Die lokale Client-Konfiguration beschreibt ausschließlich die tatsächlich
+ * gewünschten Verbindungen. Physisch vorhandene /dev/ttyUSB-Schnittstellen
+ * außerhalb des von rs2322tcp verwalteten virtuellen Bereichs werden hier
+ * nicht betrachtet.
+ *
+ * Ein Server-Gerät kann daher in drei Zuständen erscheinen:
+ *
+ *   1. lokal zugeordnet und aktuell vom Server angeboten
+ *      -> verfügbar / verbunden
+ *
+ *   2. lokal zugeordnet, aber momentan nicht vom Server angeboten
+ *      -> nicht verfügbar
+ *
+ *   3. vom Server angeboten, aber keiner lokalen Schnittstelle zugeordnet
+ *      -> noch nicht verwendet
+ *
+ * Nicht verwendete Server-Geräte werden nicht Bestandteil der
+ * Client-Konfiguration.
+ * ============================================================================
+ */
+package gui
+
+import (
+	"git.lang-dieter.de/rs2322tcp/internal/config"
+	"git.lang-dieter.de/rs2322tcp/internal/transport"
+)
+
+///////////////////////////////////////////////////////////////////////////////
+// Device assignment
+///////////////////////////////////////////////////////////////////////////////
+
+// DeviceAssignment beschreibt eine bereits in der Client-Konfiguration
+// vorhandene Zuordnung zwischen einer lokalen virtuellen Schnittstelle
+// und einem entfernten Gerät.
+//
+// Available gibt an, ob das konfigurierte Remote-Gerät momentan in der
+// vom Server gelieferten Geräteliste vorhanden ist.
+//
+// Available == false bedeutet nicht, dass die Konfiguration ungültig ist.
+// Das Gerät kann lediglich momentan nicht vom Server angeboten werden.
+type DeviceAssignment struct {
+	LocalPort    string
+	RemoteDevice string
+	Available    bool
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Build assignments
+///////////////////////////////////////////////////////////////////////////////
+
+// BuildAssignments erzeugt die Zuordnungsansicht aus der bestehenden
+// Client-Konfiguration und der aktuell vom Server gelieferten Geräteliste.
+//
+// Es werden ausschließlich die in der Client-Konfiguration vorhandenen
+// lokalen virtuellen Ports berücksichtigt.
+//
+// Physisch vorhandene serielle Schnittstellen des lokalen Rechners werden
+// hier nicht gesucht und nicht bewertet.
+func BuildAssignments(
+	cfg *config.ClientConfig,
+	devices []transport.RemoteDeviceInfo,
+) []DeviceAssignment {
+	if cfg == nil {
+		return nil
+	}
+
+	assignments := make([]DeviceAssignment, 0, len(cfg.VirtualPorts))
+
+	for _, virtualPort := range cfg.VirtualPorts {
+		assignments = append(assignments, DeviceAssignment{
+			LocalPort:    virtualPort.Port,
+			RemoteDevice: virtualPort.RemoteDevice,
+			Available: remoteDeviceExists(
+				virtualPort.RemoteDevice,
+				devices,
+			),
+		})
+	}
+
+	return assignments
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Unassigned devices
+///////////////////////////////////////////////////////////////////////////////
+
+// UnassignedDevices liefert die vom Server angebotenen Geräte, die aktuell
+// keiner lokalen virtuellen Schnittstelle zugeordnet sind.
+//
+// Diese Geräte werden bewusst nicht in die Client-Konfiguration übernommen.
+// Erst wenn der Anwender im GUI eine Zuordnung vornimmt, entsteht daraus
+// ein Eintrag in ClientConfig.VirtualPorts.
+func UnassignedDevices(
+	cfg *config.ClientConfig,
+	devices []transport.RemoteDeviceInfo,
+) []transport.RemoteDeviceInfo {
+	assigned := assignedRemoteDevices(cfg)
+
+	unassigned := make([]transport.RemoteDeviceInfo, 0)
+
+	for _, device := range devices {
+		if assigned[device.ID] {
+			continue
+		}
+
+		unassigned = append(unassigned, device)
+	}
+
+	return unassigned
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Internal helpers
+///////////////////////////////////////////////////////////////////////////////
+
+// assignedRemoteDevices erzeugt eine Menge der Remote-Geräte, die bereits
+// einer lokalen virtuellen Schnittstelle zugeordnet sind.
+//
+// Die Remote-Device-ID ist der stabile Schlüssel der Zuordnung.
+func assignedRemoteDevices(
+	cfg *config.ClientConfig,
+) map[string]bool {
+	assigned := make(map[string]bool)
+
+	if cfg == nil {
+		return assigned
+	}
+
+	for _, virtualPort := range cfg.VirtualPorts {
+		if virtualPort.RemoteDevice == "" {
+			continue
+		}
+
+		assigned[virtualPort.RemoteDevice] = true
+	}
+
+	return assigned
+}
+
+// remoteDeviceExists prüft, ob ein Remote-Gerät mit der angegebenen ID in
+// der aktuellen Geräteliste des Servers vorhanden ist.
+func remoteDeviceExists(
+	id string,
+	devices []transport.RemoteDeviceInfo,
+) bool {
+	for _, device := range devices {
+		if device.ID == id {
+			return true
+		}
+	}
+
+	return false
+}

internal/gui/assignment_test.go

@@ -0,0 +1,374 @@
+/*
+ * ============================================================================
+ * Projekt.....: rs2322tcp
+ * Datei.......: internal/gui/assignment_test.go
+ * Copyright (C) 2026 Dieter Lang
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ * Beschreibung:
+ * Tests für die GUI-unabhängige Aufbereitung der Zuordnung zwischen lokalen
+ * virtuellen seriellen Schnittstellen und den vom rs2322tcp-Server
+ * angebotenen Geräten.
+ * ============================================================================
+ */
+package gui
+
+import (
+	"testing"
+
+	"git.lang-dieter.de/rs2322tcp/internal/config"
+	"git.lang-dieter.de/rs2322tcp/internal/transport"
+)
+
+///////////////////////////////////////////////////////////////////////////////
+// Test helpers
+///////////////////////////////////////////////////////////////////////////////
+
+// testClientConfig creates a client configuration containing the supplied
+// local-to-remote assignments.
+func testClientConfig(
+	assignments ...config.VirtualPortConfig,
+) *config.ClientConfig {
+	return &config.ClientConfig{
+		VirtualPorts: assignments,
+	}
+}
+
+// testRemoteDevices creates a list of remote devices from their IDs.
+func testRemoteDevices(ids ...string) []transport.RemoteDeviceInfo {
+	devices := make([]transport.RemoteDeviceInfo, 0, len(ids))
+
+	for _, id := range ids {
+		devices = append(devices, transport.RemoteDeviceInfo{
+			ID:   id,
+			Name: id,
+		})
+	}
+
+	return devices
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// BuildAssignments tests
+///////////////////////////////////////////////////////////////////////////////
+
+func TestBuildAssignments(t *testing.T) {
+	cfg := testClientConfig(
+		config.VirtualPortConfig{
+			Port:         "/dev/ttyUSB100",
+			RemoteDevice: "radio",
+		},
+		config.VirtualPortConfig{
+			Port:         "/dev/ttyUSB101",
+			RemoteDevice: "rotor",
+		},
+	)
+
+	devices := testRemoteDevices(
+		"radio",
+		"rotor",
+		"gps",
+	)
+
+	assignments := BuildAssignments(cfg, devices)
+
+	if len(assignments) != 2 {
+		t.Fatalf(
+			"BuildAssignments() returned %d assignments, want 2",
+			len(assignments),
+		)
+	}
+
+	if assignments[0].LocalPort != "/dev/ttyUSB100" {
+		t.Errorf(
+			"assignments[0].LocalPort = %q, want %q",
+			assignments[0].LocalPort,
+			"/dev/ttyUSB100",
+		)
+	}
+
+	if assignments[0].RemoteDevice != "radio" {
+		t.Errorf(
+			"assignments[0].RemoteDevice = %q, want %q",
+			assignments[0].RemoteDevice,
+			"radio",
+		)
+	}
+
+	if !assignments[0].Available {
+		t.Error("assignments[0].Available = false, want true")
+	}
+
+	if assignments[1].LocalPort != "/dev/ttyUSB101" {
+		t.Errorf(
+			"assignments[1].LocalPort = %q, want %q",
+			assignments[1].LocalPort,
+			"/dev/ttyUSB101",
+		)
+	}
+
+	if assignments[1].RemoteDevice != "rotor" {
+		t.Errorf(
+			"assignments[1].RemoteDevice = %q, want %q",
+			assignments[1].RemoteDevice,
+			"rotor",
+		)
+	}
+
+	if !assignments[1].Available {
+		t.Error("assignments[1].Available = false, want true")
+	}
+}
+
+func TestBuildAssignmentsUnavailableDevice(t *testing.T) {
+	cfg := testClientConfig(
+		config.VirtualPortConfig{
+			Port:         "/dev/ttyUSB100",
+			RemoteDevice: "radio",
+		},
+		config.VirtualPortConfig{
+			Port:         "/dev/ttyUSB101",
+			RemoteDevice: "rotor",
+		},
+	)
+
+	devices := testRemoteDevices("rotor")
+
+	assignments := BuildAssignments(cfg, devices)
+
+	if len(assignments) != 2 {
+		t.Fatalf(
+			"BuildAssignments() returned %d assignments, want 2",
+			len(assignments),
+		)
+	}
+
+	if assignments[0].RemoteDevice != "radio" {
+		t.Errorf(
+			"assignments[0].RemoteDevice = %q, want %q",
+			assignments[0].RemoteDevice,
+			"radio",
+		)
+	}
+
+	if assignments[0].Available {
+		t.Error("radio assignment marked available, want unavailable")
+	}
+
+	if assignments[1].RemoteDevice != "rotor" {
+		t.Errorf(
+			"assignments[1].RemoteDevice = %q, want %q",
+			assignments[1].RemoteDevice,
+			"rotor",
+		)
+	}
+
+	if !assignments[1].Available {
+		t.Error("rotor assignment marked unavailable, want available")
+	}
+}
+
+func TestBuildAssignmentsNilConfig(t *testing.T) {
+	devices := testRemoteDevices("radio")
+
+	assignments := BuildAssignments(nil, devices)
+
+	if assignments != nil {
+		t.Fatalf(
+			"BuildAssignments(nil, ...) = %#v, want nil",
+			assignments,
+		)
+	}
+}
+
+func TestBuildAssignmentsEmptyConfig(t *testing.T) {
+	cfg := testClientConfig()
+
+	devices := testRemoteDevices(
+		"radio",
+		"rotor",
+	)
+
+	assignments := BuildAssignments(cfg, devices)
+
+	if len(assignments) != 0 {
+		t.Fatalf(
+			"BuildAssignments() returned %d assignments, want 0",
+			len(assignments),
+		)
+	}
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// UnassignedDevices tests
+///////////////////////////////////////////////////////////////////////////////
+
+func TestUnassignedDevices(t *testing.T) {
+	cfg := testClientConfig(
+		config.VirtualPortConfig{
+			Port:         "/dev/ttyUSB100",
+			RemoteDevice: "radio",
+		},
+		config.VirtualPortConfig{
+			Port:         "/dev/ttyUSB101",
+			RemoteDevice: "rotor",
+		},
+	)
+
+	devices := testRemoteDevices(
+		"radio",
+		"rotor",
+		"gps",
+		"tnc",
+	)
+
+	unassigned := UnassignedDevices(cfg, devices)
+
+	if len(unassigned) != 2 {
+		t.Fatalf(
+			"UnassignedDevices() returned %d devices, want 2",
+			len(unassigned),
+		)
+	}
+
+	if unassigned[0].ID != "gps" {
+		t.Errorf(
+			"unassigned[0].ID = %q, want %q",
+			unassigned[0].ID,
+			"gps",
+		)
+	}
+
+	if unassigned[1].ID != "tnc" {
+		t.Errorf(
+			"unassigned[1].ID = %q, want %q",
+			unassigned[1].ID,
+			"tnc",
+		)
+	}
+}
+
+func TestUnassignedDevicesAllAssigned(t *testing.T) {
+	cfg := testClientConfig(
+		config.VirtualPortConfig{
+			Port:         "/dev/ttyUSB100",
+			RemoteDevice: "radio",
+		},
+		config.VirtualPortConfig{
+			Port:         "/dev/ttyUSB101",
+			RemoteDevice: "rotor",
+		},
+	)
+
+	devices := testRemoteDevices(
+		"radio",
+		"rotor",
+	)
+
+	unassigned := UnassignedDevices(cfg, devices)
+
+	if len(unassigned) != 0 {
+		t.Fatalf(
+			"UnassignedDevices() returned %d devices, want 0",
+			len(unassigned),
+		)
+	}
+}
+
+func TestUnassignedDevicesEmptyConfig(t *testing.T) {
+	cfg := testClientConfig()
+
+	devices := testRemoteDevices(
+		"radio",
+		"rotor",
+	)
+
+	unassigned := UnassignedDevices(cfg, devices)
+
+	if len(unassigned) != 2 {
+		t.Fatalf(
+			"UnassignedDevices() returned %d devices, want 2",
+			len(unassigned),
+		)
+	}
+}
+
+func TestUnassignedDevicesNilConfig(t *testing.T) {
+	devices := testRemoteDevices(
+		"radio",
+		"rotor",
+	)
+
+	unassigned := UnassignedDevices(nil, devices)
+
+	if len(unassigned) != 2 {
+		t.Fatalf(
+			"UnassignedDevices(nil, ...) returned %d devices, want 2",
+			len(unassigned),
+		)
+	}
+}
+
+func TestUnassignedDevicesEmptyServerList(t *testing.T) {
+	cfg := testClientConfig(
+		config.VirtualPortConfig{
+			Port:         "/dev/ttyUSB100",
+			RemoteDevice: "radio",
+		},
+	)
+
+	unassigned := UnassignedDevices(cfg, nil)
+
+	if len(unassigned) != 0 {
+		t.Fatalf(
+			"UnassignedDevices() returned %d devices, want 0",
+			len(unassigned),
+		)
+	}
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Existing configuration does not change
+///////////////////////////////////////////////////////////////////////////////
+
+func TestAssignmentFunctionsDoNotModifyConfig(t *testing.T) {
+	cfg := testClientConfig(
+		config.VirtualPortConfig{
+			Port:         "/dev/ttyUSB100",
+			RemoteDevice: "radio",
+		},
+	)
+
+	devices := testRemoteDevices(
+		"radio",
+		"rotor",
+		"gps",
+	)
+
+	_ = BuildAssignments(cfg, devices)
+	_ = UnassignedDevices(cfg, devices)
+
+	if len(cfg.VirtualPorts) != 1 {
+		t.Fatalf(
+			"configuration contains %d virtual ports, want 1",
+			len(cfg.VirtualPorts),
+		)
+	}
+
+	if cfg.VirtualPorts[0].Port != "/dev/ttyUSB100" {
+		t.Errorf(
+			"configuration port = %q, want %q",
+			cfg.VirtualPorts[0].Port,
+			"/dev/ttyUSB100",
+		)
+	}
+
+	if cfg.VirtualPorts[0].RemoteDevice != "radio" {
+		t.Errorf(
+			"configuration remote device = %q, want %q",
+			cfg.VirtualPorts[0].RemoteDevice,
+			"radio",
+		)
+	}
+}