move linux config path to /opt/epson-print-service

EpsonPrintService/ConfigurationPaths.cs

@@ -4,7 +4,7 @@ namespace EpsonPrintService;
 
 public static class ConfigurationPaths
 {
-    private const string LinuxConfigDir = "/root/epsonprintservice";
+    private const string LinuxConfigDir = "/opt/epson-print-service";
     private const string LocalConfigFileName = "config.txt";
 
     public static string GetConfigPath()

Inspectron.Epson.Tests/Configuration/ConfigurationPathsTests.cs

@@ -0,0 +1,40 @@
+using System.Runtime.InteropServices;
+using EpsonPrintService;
+
+namespace Inspectron.Epson.Tests.Configuration;
+
+public class ConfigurationPathsTests
+{
+    [Fact]
+    public void GetConfigPath_uses_opt_dir_on_linux_when_env_unset_and_no_local_file()
+    {
+        if (!RuntimeInformation.IsOSPlatform(OSPlatform.Linux)) return;
+        var previous = Environment.GetEnvironmentVariable("EPSON_CONFIG_PATH");
+        Environment.SetEnvironmentVariable("EPSON_CONFIG_PATH", null);
+        try
+        {
+            var path = ConfigurationPaths.GetConfigPath();
+            Assert.Equal("/opt/epson-print-service/config.txt", path);
+        }
+        finally
+        {
+            Environment.SetEnvironmentVariable("EPSON_CONFIG_PATH", previous);
+        }
+    }
+
+    [Fact]
+    public void EPSON_CONFIG_PATH_override_still_wins()
+    {
+        var previous = Environment.GetEnvironmentVariable("EPSON_CONFIG_PATH");
+        Environment.SetEnvironmentVariable("EPSON_CONFIG_PATH", "/tmp/override.txt");
+        try
+        {
+            var path = ConfigurationPaths.GetConfigPath();
+            Assert.Equal("/tmp/override.txt", path);
+        }
+        finally
+        {
+            Environment.SetEnvironmentVariable("EPSON_CONFIG_PATH", previous);
+        }
+    }
+}