Running doc tests are slow due to being always being recompiled
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- Dominant language
- Rust
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Description
Originally spawned by an issue to rust-skeptic which has the same problem.
Testing my combine library which has 44 doc tests and 36 normal tests takes ~26 seconds with ~22 of those being spent in doc tests. From what I can tell this is because cargo recompiles these tests every time cargo test is run in addition to each test being compiled individually.
I am thinking this is for a good reason since it makes sure two doc tests cannot conflict with each other but it would be nice if it could be improved.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the reported timing with cargo test on a project containing many doc tests, and compare doc-test compilation with normal tests. Read the doc-test and test-running paths in Cargo, using the linked rust-skeptic issue for context. Done means avoiding unnecessary recompilation while preserving isolation between doc tests.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- build-system, testing-qa
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100