Finish the libtest json output experiment

[nikomatsakis]

Metadata
Point of contact	@epage
Team(s)	cargo, libs-api, testing-devex
Goal document	2026/libtest-json

Summary

Finish the libtest json experiment.

Tasks and status

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Note: we have updated the body to match the 2026 goal. Your original text is preserved below.

Details

Metadata
Point of contact	@epage
Team(s)	cargo, libs-api, testing-devex
Goal document	2025h2/libtest-json

Summary

Finish the libtest json experiment.

Tasks and status

• Discussion and moral support (testing-devex, cargo, libs-api )
• Prototype harness (@epage)
• Prototype Cargo reporting support (@epage)
• Write stabilization report (@epage)

---

Note: we have updated the body to match the 2025h2 goal. Your original text is preserved below.

Metadata
Point of contact	@epage
Team(s)	cargo, libs-api, testing-devex
Goal document	2025h1/libtest-json

Summary

Finish the libtest json experiment.

Tasks and status

• Discussion and moral support (testing-devex, cargo, libs-api )
• Prototype harness (@epage)
• Prototype Cargo reporting support (@epage)
• Write stabilization report (@epage)

[nikomatsakis]

This issue is intended for status updates only.

For general questions or comments, please contact the owner(s) directly.

[epage]

This is on pause until the implementation for #92 is finished. The rustc side of #92 is under review and then some additional r-a and cargo work before implementation is done and its waiting on testing and stabilization.

[epage]

• Key developments:
  • Between tasks on Stabilize cargo-script #92, I've started to refresh myself on the libtest-next code base
• Blockers:
• Help wanted:

[epage]

• Key developments:
  • Continued efforts to clean up the existing code
  • t-testing-devex has been working out where the crates should live in preparation for publishing them (#t-testing-devex > crate ownership @ 💬)
  • Looking to build on the work done for test-r and rustest crates as they align with the long term vision
• Blockers:
• Help wanted:

[epage]

• Key developments:
  • Moved crates to https://github.com/crate-ci/libtest2
• Blockers
• Help wanted

[epage]

Key developments:

Blockers

• Staffing wise, attention was taken by toml v0.9 and now cargo-script

Help wanted

• Help in writing out the end-user API on top of the raw harness

[epage]

Key developments:

• feat(json): Split out into its own crate assert-rs/libtest2#94
• fix(json)!: Bring schema up to modern cargo expectations assert-rs/libtest2#99
• perf: Allow writing json without serde assert-rs/libtest2#100

[nikomatsakis]

This is a continuing project goal, and the updates below this comment will be for the new period 2025h2