rs2322tcp/internal/client/application_test.go

/*
 * ============================================================================
 * Projekt.....: rs2322tcp
 * Datei.......: internal/client/application_test.go
 * Copyright (C) 2026 Dieter Lang
 *
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 * Beschreibung:
 * Tests für die Anwendungsschicht des rs2322tcp-Clients.
 *
 * Die Tests prüfen zunächst den Lebenszyklus der Application, 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.
 * ============================================================================
 */

package client

import "testing"

///////////////////////////////////////////////////////////////////////////////
// NewApplication
///////////////////////////////////////////////////////////////////////////////

// TestNewApplicationRejectsEmptyConfigFile verifies that an empty
// configuration-file path is rejected.
func TestNewApplicationRejectsEmptyConfigFile(t *testing.T) {
	t.Helper()

	application, err := NewApplication("")
	if err == nil {
		t.Fatal("NewApplication with empty config file returned no error")
	}

	if application != nil {
		t.Fatal("NewApplication with empty config file returned an application")
	}
}

// TestNewApplication verifies that a valid configuration-file path creates
// an application without starting it.
func TestNewApplication(t *testing.T) {
	t.Helper()

	application, err := NewApplication("client.json")
	if err != nil {
		t.Fatalf("NewApplication: %v", err)
	}

	if application == nil {
		t.Fatal("NewApplication returned nil application")
	}

	if application.Running() {
		t.Fatal("new application reports running")
	}

	if application.Config() != nil {
		t.Fatal("new application returned a configuration")
	}

	if devices := application.Devices(); len(devices) != 0 {
		t.Fatalf(
			"new application returned %d devices",
			len(devices),
		)
	}
}

///////////////////////////////////////////////////////////////////////////////
// Close
///////////////////////////////////////////////////////////////////////////////

// TestApplicationCloseBeforeStart verifies that Close can safely be called
// before the application has been started.
func TestApplicationCloseBeforeStart(t *testing.T) {
	t.Helper()

	application, err := NewApplication("client.json")
	if err != nil {
		t.Fatalf("NewApplication: %v", err)
	}

	if err := application.Close(); err != nil {
		t.Fatalf("Close before Start: %v", err)
	}

	if application.Running() {
		t.Fatal("application reports running after Close")
	}
}

// TestApplicationCloseIsIdempotent verifies that Close can be called more
// than once without producing an error.
func TestApplicationCloseIsIdempotent(t *testing.T) {
	t.Helper()

	application, err := NewApplication("client.json")
	if err != nil {
		t.Fatalf("NewApplication: %v", err)
	}

	if err := application.Close(); err != nil {
		t.Fatalf("first Close: %v", err)
	}

	if err := application.Close(); err != nil {
		t.Fatalf("second Close: %v", err)
	}

	if application.Running() {
		t.Fatal("application reports running after repeated Close")
	}
}

///////////////////////////////////////////////////////////////////////////////
// Nil receiver
///////////////////////////////////////////////////////////////////////////////

// TestNilApplication verifies that the public lifecycle methods behave
// safely when called on a nil Application receiver.
//
// This is deliberately a small defensive test. The GUI should normally
// never operate on a nil Application.
func TestNilApplication(t *testing.T) {
	t.Helper()

	var application *Application

	if err := application.Start(); err == nil {
		t.Fatal("nil Application Start returned no error")
	}

	if err := application.Reconnect(); err == nil {
		t.Fatal("nil Application Reconnect returned no error")
	}

	if err := application.Close(); err != nil {
		t.Fatalf("nil Application Close: %v", err)
	}

	if application.Running() {
		t.Fatal("nil Application reports running")
	}

	if application.Config() != nil {
		t.Fatal("nil Application returned a configuration")
	}

	if devices := application.Devices(); devices != nil {
		t.Fatal("nil Application returned devices")
	}
}