Allow overriding OneWire sysfs paths for testing#2478

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florianraffl wants to merge 1 commit intodotnet:mainfrom

florianraffl:overriding_onewire_path

florianraffl commented Feb 24, 2026 •

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Fixes #2477

Changed SysfsBusDevicesPath and SysfsDevicesPath from const to static string fields to enable runtime modification. Added OverwriteSysfsBusDevicesPath and OverwriteSysfsDevicesPath methods to allow setting custom sysfs directories, with validation. This facilitates testing and use in non-standard environments.

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          Allow overriding OneWire sysfs paths for testing

2b4a75f

Changed SysfsBusDevicesPath and SysfsDevicesPath from const to static string fields to enable runtime modification. Added OverwriteSysfsBusDevicesPath and OverwriteSysfsDevicesPath methods to allow setting custom sysfs directories, with validation. This facilitates testing and use in non-standard environments.

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Author

florianraffl commented Feb 24, 2026

@dotnet-policy-service agree

Contributor

raffaeler commented Feb 24, 2026

@copilot review the pull-request according to the repo policies

joperezr requested a review from Copilot

February 24, 2026 17:55

Copilot started reviewing on behalf of joperezr

February 24, 2026 17:56

Copilot AI reviewed

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Copilot AI left a comment

Pull request overview

This pull request enables testing of OneWire device bindings by making sysfs paths configurable at runtime. The changes address issue #2477, which requested the ability to override hardcoded sysfs paths for integration testing scenarios.

Changes:

Converted SysfsBusDevicesPath and SysfsDevicesPath from const to static string fields to allow runtime modification
Added two public static methods (OverwriteSysfsBusDevicesPath and OverwriteSysfsDevicesPath) with directory validation to set custom paths for testing

src/devices/OneWire/OneWireBus.Linux.cs

+                      {
+                          if (!Directory.Exists(path))
+                          {
+                              throw new ArgumentException($"Provided path {path} does not exist or is not a directory.");

Copilot AI Feb 24, 2026

The parameter name in the exception message should use nameof(path) instead of a string literal for consistency with the repository's error handling patterns. This ensures that parameter names stay synchronized if they are ever renamed during refactoring.

Copilot uses AI. Check for mistakes.

src/devices/OneWire/OneWireBus.Linux.cs

Comment on lines +80 to +88

+                      public static void OverwriteSysfsBusDevicesPath(string path)
+                      {
+                          if (!Directory.Exists(path))
+                          {
+                              throw new ArgumentException($"Provided path {path} does not exist or is not a directory.");
+                          }
+                          SysfsBusDevicesPath = path;
+                      }

Copilot AI Feb 24, 2026

Missing null validation for the path parameter. The repository consistently uses ArgumentNullException for null parameters (see examples in Ads1115, Adxl345, etc.). Add a null check before the Directory.Exists check.

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src/devices/OneWire/OneWireBus.Linux.cs

Comment on lines +95 to +103

+                      public static void OverwriteSysfsDevicesPath(string path)
+                      {
+                          if (!Directory.Exists(path))
+                          {
+                              throw new ArgumentException($"Provided path {path} does not exist or is not a directory.");
+                          }
+                          SysfsDevicesPath = path;
+                      }

Copilot AI Feb 24, 2026

Missing null validation for the path parameter. The repository consistently uses ArgumentNullException for null parameters (see examples in Ads1115, Adxl345, etc.). Add a null check before the Directory.Exists check.

Copilot uses AI. Check for mistakes.

src/devices/OneWire/OneWireBus.Linux.cs

Comment on lines 15 to +103

                           File.WriteAllText(Path.Combine(SysfsDevicesPath, bus.BusId, "w1_master_search"), numScans.ToString());
                       }
+                      /// <summary>
+                      /// Sets the bus path to the specified directory for testing purpose.
+                      /// </summary>
+                      /// <param name="path">The path to the directory that will be set as the bus path. This path must exist and be a valid directory.</param>
+                      /// <exception cref="ArgumentException">Thrown if the specified path does not exist or is not a directory.</exception>
+                      public static void OverwriteSysfsBusDevicesPath(string path)
+                      {
+                          if (!Directory.Exists(path))
+                          {
+                              throw new ArgumentException($"Provided path {path} does not exist or is not a directory.");
+                          }
+                          SysfsBusDevicesPath = path;
+                      }
+                      /// <summary>
+                      /// Sets the devices path to the specified directory for testing purpose.
+                      /// </summary>
+                      /// <param name="path">The path to the directory that will be set as the devices path. This path must exist and be a valid directory.</param>
+                      /// <exception cref="ArgumentException">Thrown if the provided path does not exist or is not a directory.</exception>
+                      public static void OverwriteSysfsDevicesPath(string path)
+                      {
+                          if (!Directory.Exists(path))
+                          {
+                              throw new ArgumentException($"Provided path {path} does not exist or is not a directory.");
+                          }
+                          SysfsDevicesPath = path;
+                      }

Copilot AI Feb 24, 2026

The static mutable fields SysfsBusDevicesPath and SysfsDevicesPath present thread safety concerns. Multiple threads could read these paths while they are being modified, leading to race conditions. Additionally, there is no mechanism to restore the paths to their original values after testing. Consider: (1) using volatile or Interlocked operations for thread-safe updates, (2) providing Reset methods to restore defaults, or (3) documenting that these methods should only be called before any OneWire operations in a single-threaded test setup context.

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Contributor

pgrawehr Feb 28, 2026

I agree to Copilot here. I suggest you make the strings non-static so that a change only affects the current instance.

src/devices/OneWire/OneWireBus.Linux.cs

Comment on lines +75 to +103

+                      /// <summary>
+                      /// Sets the bus path to the specified directory for testing purpose.
+                      /// </summary>
+                      /// <param name="path">The path to the directory that will be set as the bus path. This path must exist and be a valid directory.</param>
+                      /// <exception cref="ArgumentException">Thrown if the specified path does not exist or is not a directory.</exception>
+                      public static void OverwriteSysfsBusDevicesPath(string path)
+                      {
+                          if (!Directory.Exists(path))
+                          {
+                              throw new ArgumentException($"Provided path {path} does not exist or is not a directory.");
+                          }
+                          SysfsBusDevicesPath = path;
+                      }
+                      /// <summary>
+                      /// Sets the devices path to the specified directory for testing purpose.
+                      /// </summary>
+                      /// <param name="path">The path to the directory that will be set as the devices path. This path must exist and be a valid directory.</param>
+                      /// <exception cref="ArgumentException">Thrown if the provided path does not exist or is not a directory.</exception>
+                      public static void OverwriteSysfsDevicesPath(string path)
+                      {
+                          if (!Directory.Exists(path))
+                          {
+                              throw new ArgumentException($"Provided path {path} does not exist or is not a directory.");
+                          }
+                          SysfsDevicesPath = path;
+                      }

Copilot AI Feb 24, 2026

Consider adding methods to reset paths to their default values for proper test isolation. Tests that modify these static paths should be able to restore the original state to avoid test interdependencies. For example, add ResetSysfsBusDevicesPath() and ResetSysfsDevicesPath() methods that restore the default "/sys/bus/w1/devices" and "/sys/devices" values respectively.

Copilot uses AI. Check for mistakes.

src/devices/OneWire/OneWireBus.Linux.cs

+                      {
+                          if (!Directory.Exists(path))
+                          {
+                              throw new ArgumentException($"Provided path {path} does not exist or is not a directory.");

Copilot AI Feb 24, 2026

The parameter name in the exception message should use nameof(path) instead of a string literal for consistency with the repository's error handling patterns. This ensures that parameter names stay synchronized if they are ever renamed during refactoring.

Copilot uses AI. Check for mistakes.

pgrawehr requested changes

View reviewed changes

src/devices/OneWire/OneWireBus.Linux.cs

Comment on lines +15 to +16

		internal static string SysfsBusDevicesPath = "/sys/bus/w1/devices";
		internal static string SysfsDevicesPath = "/sys/devices";

Contributor

pgrawehr Feb 28, 2026

I suggest to make these (and the corresponding methods) non-static, to avoid concurrency issues. It also looks like they could be private.

src/devices/OneWire/OneWireBus.Linux.cs

+                      /// </summary>
+                      /// <param name="path">The path to the directory that will be set as the bus path. This path must exist and be a valid directory.</param>
+                      /// <exception cref="ArgumentException">Thrown if the specified path does not exist or is not a directory.</exception>
+                      public static void OverwriteSysfsBusDevicesPath(string path)

Contributor

pgrawehr Feb 28, 2026

To simplify the API, I think a single method to set both paths would be sufficient.

src/devices/OneWire/OneWireBus.Linux.cs

Comment on lines 15 to +103

                           File.WriteAllText(Path.Combine(SysfsDevicesPath, bus.BusId, "w1_master_search"), numScans.ToString());
                       }
+                      /// <summary>
+                      /// Sets the bus path to the specified directory for testing purpose.
+                      /// </summary>
+                      /// <param name="path">The path to the directory that will be set as the bus path. This path must exist and be a valid directory.</param>
+                      /// <exception cref="ArgumentException">Thrown if the specified path does not exist or is not a directory.</exception>
+                      public static void OverwriteSysfsBusDevicesPath(string path)
+                      {
+                          if (!Directory.Exists(path))
+                          {
+                              throw new ArgumentException($"Provided path {path} does not exist or is not a directory.");
+                          }
+                          SysfsBusDevicesPath = path;
+                      }
+                      /// <summary>
+                      /// Sets the devices path to the specified directory for testing purpose.
+                      /// </summary>
+                      /// <param name="path">The path to the directory that will be set as the devices path. This path must exist and be a valid directory.</param>
+                      /// <exception cref="ArgumentException">Thrown if the provided path does not exist or is not a directory.</exception>
+                      public static void OverwriteSysfsDevicesPath(string path)
+                      {
+                          if (!Directory.Exists(path))
+                          {
+                              throw new ArgumentException($"Provided path {path} does not exist or is not a directory.");
+                          }
+                          SysfsDevicesPath = path;
+                      }

Contributor

pgrawehr Feb 28, 2026

I agree to Copilot here. I suggest you make the strings non-static so that a change only affects the current instance.

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dotnet-policy-service bot commented Mar 8, 2026

This pull request has been automatically marked as stale because it has been marked as requiring author feedback but has not had any activity for 7 days.

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