Generator

This document describes how the Roslyn structure test generator works in bsharp_compliance and how it produces executable tests for bsharp_compliance_testing.

Inputs

• Roslyn source files under roslyn_testing/roslyn_repo/src/Compilers/CSharp/Test/Syntax/Parsing/.
• The generator scans for UsingTree(...) calls and parses the immediately following Roslyn structure DSL composed of N(SyntaxKind.X) and EOF() entries (with M(...) ignored as "missing").

Pipeline

1. Scan and collect test methods

   • Locates Roslyn [Fact] methods and all UsingTree(...) call sites.
   • Captures the closest preceding var text = "..."; snippet as input source, when present.

2. Parse structure DSL

   • Reads the DSL block following UsingTree(...) and constructs a nested ExpectedTree (ExpectedNode graph) mirroring the Roslyn node hierarchy.
   • Tolerates whitespace, comments, and missing markers (M(...)).

3. Kind translation and normalization

   • generator/kind_map.rs maps Roslyn kinds to our canonical naming (PascalCase, no Syntax suffix).
   • Filters token/keyword nodes, lifting identifier text (IdentifierToken → parent IdentifierName.token_value).
   • Applies targeted renames (e.g., RecordStructDeclaration → RecordDeclaration).

4. Emit tests

   • Writes Rust tests into bsharp_compliance_testing/src/generated/<module>.rs.
   • Each test parses the captured src with bsharp_parser and asserts structure via custom_asserts/structure_assert.rs.

Assertions

• Structure assertions build a comparable expected tree from our actual AST (bsharp_syntax) and compare:
  • Node kinds and order
  • Selected token payloads (e.g., IdentifierName.token_value)
• Normalization in the assert layer adapts Roslyn’s harness (class + method) to our top-level statements when applicable.

Extending the Generator

• Update generator/kind_map.rs to add or refine kind mappings.
• Expand custom_asserts/structure_assert.rs to walk deeper AST areas (e.g., records, types, constraints).
• Improve the DSL parser (generator/structure_dsl.rs) as new Roslyn DSL shapes appear.

Output Location

• Generated files live under roslyn_testing/bsharp_compliance_testing/src/generated/.
• Modules track Roslyn file groups, e.g. record_parsing.rs, using_directive_parsing_tests.rs.