Reduce custom testing code in cargo with snapbox

[epage]

Problem

There is a lot of custom test code in cargo-test-support, including diffing, diff rendering, eliding in diffs, etc. Sharing the implementation outside of cargo would help reduce the scope of what cargo needs to maintain and allow every to benefit from improvements.

Steps

See cargo-test-support

Possible Solution(s)

Port to snapbox

• It was partially modeled off of cargo-test-support
• We are already using it with feat: Import cargo-add into cargo #10472

Notes

Remaining work

• Generalize helpers on top of snapbox (Integrate snapbox in with cargo-test-support #10581)
• Re-org snapshot files for easier IDE browsing (reorganize snapshot tests to better work in contexts that sort by extension #10629)
• Hard to review snapshots because they are far from their intended code #10627
• New testing style isn't documented #10628
• Structured data (like json, ndjson, toml, yaml) asserts in snapbox  assert-rs/snapbox#92
• Come up with a strategy for unordered assertions
• Port cargo's tests to new the new style

Version

No response