Description

ProcessOutputLine.ToString() returned the default type name ("System.Diagnostics.ProcessOutputLine"), making Console.WriteLine(line) useless without explicitly accessing .Content.

This adds a ToString() override returning Content ?? string.Empty, following the same pattern used by StringSegment and StringValues in Microsoft.Extensions.Primitives. The ?? string.Empty guard ensures the method never returns null for a default-initialized struct, which aligns with the .NET docs requirement that ToString() should not return null or string.Empty as a meaningful value in normal usage:

await foreach (var line in process!.ReadAllLinesAsync())
{
    Console.WriteLine(line); // now prints actual output instead of type name
}

Changes

• ProcessOutputLine.cs: Added public override string ToString() => Content ?? string.Empty;
• ref/System.Diagnostics.Process.cs: Added ToString() to the reference assembly
• ProcessStreamingTests.cs: Added unit tests for ToString() behavior; default struct case asserts string.Empty