synthetic-schema-codegen-test

name	synthetic-schema-codegen-test
description	Sets up synthetic tests for jsonschemars codegen by creating a dummy Rust crate, generating Rust from JSON Schema definitions, analyzing compilation issues, and documenting findings in todo.txt with minimal viable examples. Use when running codegen analysis on external schemas, setting up regression test harnesses, or adding new bug entries to todo.txt.

Synthetic Schema Codegen Test

Automates setup of a synthetic test harness: dummy crate, jsonschemars generate rust, build analysis, and todo.txt updates. Use this when analyzing codegen issues from external JSON Schema sources.

Synthetic Data Only

For every issue added to todo.txt, create synthetic minimal viable bug data. Do not use real schemas from external sources (e.g. user-provided files). Use placeholder schemas that reproduce the same error type. Example: {"type":"object","properties":{"x":{"type":"string"}}} instead of referencing actual schema content.

Workflow

1. Create Dummy Lib Crate

Create a lib crate at the desired location (e.g. schema_models/):

• Cargo.toml: Use the latest Rust edition and rust-version (match the json-schema-rs workspace), path deps to json-schema-rs workspace
• Lints: Copy strict Rust and Clippy settings from workspace root Cargo.toml
• lib.rs: pub mod generated;

2. Run jsonschemars CLI

jsonschemars generate rust <path-to-schemas-dir> -o <path>/src/generated

Do not post-process the output. Leave all issues as-is for documentation.

3. Analyze Build Errors

Run each command in the dummy crate in a separate run so issues can be categorized by tool:

• cargo build — compilation errors
• cargo check — type-check errors
• cargo clippy — lint violations
• cargo fmt --check — formatting deviations

Capture and group errors by kind and tool. Cross-reference with design.md.

4. Update todo.txt

For each issue category, append an entry with a minimal viable example (MVE):

- [Codegen bug] <Category>: <brief description>.
  MVE:
    Input: <minimal synthetic JSON Schema - not real data>
    Current: <what codegen emits today>
    Expected: <what would fix it>
  Fix: <one-line idea>

MVE Requirements

Field	Rule
Input	Minimal synthetic schema that triggers the issue; never reference external schema content
Current	Exact or representative codegen output today
Expected	What should be emitted for the issue to be resolved

Key Files

• CLI: json_schema_rs/src/cli/generate.rs
• Rust backend: json_schema_rs/src/code_gen/rust_backend.rs
• Design: design.md
• Todo list: todo.txt