[Feature]: Textual Notation validation — 14-Language Extensions (Language Extensions) #301

What type of issue is this?

• Bug report
• Feature request

Prerequisites

• I have written a descriptive issue title
• I have verified that I am running the latest version of the SysML2.NET
• I have searched open and closed issues to ensure it has not already been reported

Description

Sub-task of #288 — extend TextualNotationValidationTestFixture.VerifyValidationTextualNotationXmi to cover every validation model in the Pilot Implementation folder 14-Language Extensions (Language Extensions).

Source files live under https://github.com/Systems-Modeling/SysML-v2-Pilot-Implementation/tree/master/sysml/src/validation/14-Language Extensions.

Files to add

• 14a-Language Extensions.sysml
• 14b-Language Extensions.sysml
• 14c-Language Extensions.sysml

Work to do

1. For each *.sysml file above, produce the matching *.sysmlx (XMI) artifact and drop it under SysML2.NET.Serializer.TextualNotation.Tests/Validation/14-Language Extensions/.
2. Register each new file in SysML2.NET.Serializer.TextualNotation.Tests/SysML2.NET.Serializer.TextualNotation.Tests.csproj with CopyToOutputDirectory=PreserveNewest (or whatever pattern is already used for folder 01-Parts Tree).
3. Add a [TestCase("14-Language Extensions", "<file>.sysmlx")] entry per file to VerifyValidationTextualNotationXmi in SysML2.NET.Serializer.TextualNotation.Tests/Writers/TextualNotationValidationTestFixture.cs.
4. Run the fixture. For every file that throws or produces clearly wrong output, either fix the underlying writer/grammar issue or open a focused follow-up issue and link it here. The acceptance criterion is green tests, not skipped tests — do not comment out failing cases.

Acceptance

• All files in the list above are present under SysML2.NET.Serializer.TextualNotation.Tests/Validation/14-Language Extensions/ and copied to the test output.
• One [TestCase] per file is wired up.
• The fixture passes green; any defects surfaced have either been fixed or filed as follow-ups linked from this issue.

Steps to Reproduce

System Configuration

• SysML2.NET version: 0.22.0
• Environment (Operating system, version and so on): Windows 11
• .NET Framework version: .NET 10 / netstandard2.1
• Additional information: tracked by umbrella issue [Feature]: Expand Textual Notation validation coverage with full Pilot Implementation suite #288