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Jakub Beránek 4b1deef096
Rollup merge of #145269 - epage:test-env, r=jhpratt
Deprecate RUST_TEST_* env variables

Like with rust-lang/rust#139224, this is a documentation-only deprecation for now. Over time, we can
- warn and then remove on use of unstable environment variables
- warn on use of stable environment variables (no plan to remove due to compatibility)

Longer term, we expect test runners, like `cargo test`, to provide the necessary mechanisms for environmental or persistent configuration (e.g. using cargo config which supports `.cargo/config.toml` as well as environment variables).

This would include:
- `RUST_TEST_THREADS`
- `RUST_TEST_NOCAPTURE`
- `RUST_TEST_SHUFFLE` (unstable)
- `RUST_TEST_SHUFFLE_SEED` (unstable)

The primary outcomes for this change are
- Reducing the scope of what is expected for custom test harnesses to implement
- Reduce the mechanisms that test runners, like `cargo test`, are expected to track when they are being bypassed to protect against negative interactions, e.g.  `RUST_TEST_NOCAPTURE=1` when json output is being read.

For testing-devex FCP, see rust-lang/testing-devex-team#10

Fixes rust-lang/testing-devex-team#10

History
-------

At each step, I could not find evidence of design discussions on whether to support CLI, env, or both.  The first env variable seems to come from the fact that it was being forked out of an existing env variable that had a much wider scope.

At best, this seems like a way to offer a more persistent configuration for these flags but environment variables hidden away in libtest is a bit clunky and this seems like the wrong layer to handle this problem.

**Originally:** `RUST_THREADS` was respected by the Rust runtime and libextra/test got this for free

**2013:** rust-lang/rust#7335 suggested splitting `RUST_TEST_TASKS` out of `RUST_THREADS`.  In that issue and the implementation (rust-lang/rust#8823).

**2014:** rust-lang/rust#13374 ask for support to disable capturing of stdout/stderr.  `--nocapture` and `RUST_TEST_NOCAPTURE` were added together.

**2015:** rust-lang/rust#23525 renamed `RUST_TEST_TASKS` to `RUST_TEST_THREADS`

**2016:** rust-lang/rust#25636 asked to configure `RUST_TEST_THREADS` via `--test-threads` which was implemented in rust-lang/rust#35414

**2021:** rust-lang/rust#85440 asked for test randomization which was implemented in rust-lang/rust#89082, adding `--shuffle` / RUST_TEST_SHUFFLE` and `--shuffle-seed SEED` / `RUST_TEST_SHUFFLE_SEED`

Potentially relevant issues
---------------------------

- rust-lang/rust#74845
2025-08-13 07:03:48 +02:00
.github improve "Documentation problem" issue template. 2025-08-09 12:27:19 -05:00
compiler Auto merge of #144678 - jdonszelmann:no-mangle-extern, r=bjorn3 2025-08-12 16:20:24 +00:00
library Rollup merge of #145269 - epage:test-env, r=jhpratt 2025-08-13 07:03:48 +02:00
LICENSES Synchronize Unicode license text from unicode.org 2024-11-20 00:54:12 -08:00
src Rollup merge of #145269 - epage:test-env, r=jhpratt 2025-08-13 07:03:48 +02:00
tests Auto merge of #144678 - jdonszelmann:no-mangle-extern, r=bjorn3 2025-08-12 16:20:24 +00:00
.clang-format Add .clang-format 2024-06-26 05:56:00 +08:00
.editorconfig editorconfig: don't trim trailing whitespace in tests 2025-08-08 11:15:28 -05:00
.git-blame-ignore-revs git: ignore 60600a6fa4 for blame purposes 2025-04-17 11:50:24 +08:00
.gitattributes Mark .pp files as Rust 2025-03-29 12:39:06 +01:00
.gitignore tidy: use a lockfile for js tools instead of npx 2025-07-19 14:44:15 -05:00
.gitmodules Update to LLVM 21 2025-08-01 10:17:04 +02:00
.ignore change config.toml to bootstrap.toml for bootstrap module 2025-03-17 12:56:41 +05:30
.mailmap Add my previous commit name to .mailmap 2025-08-01 21:59:56 +02:00
bootstrap.example.toml Clarify the behavior of rust.codegen-backends 2025-08-08 11:35:10 +02:00
Cargo.lock Update sysinfo version to 0.37.0 2025-08-11 14:21:01 +02:00
Cargo.toml Bump Clippy version -> 0.1.91 2025-08-07 16:48:16 +02:00
CODE_OF_CONDUCT.md Remove the code of conduct; instead link https://www.rust-lang.org/conduct.html 2019-10-05 22:55:19 +02:00
configure Ensure ./configure works when configure.py path contains spaces 2024-02-16 18:57:22 +00:00
CONTRIBUTING.md Task priority 2025-08-04 01:50:44 +05:00
COPYRIGHT dist: Re-work how we describe the licence of Rust in our distributions 2024-12-09 10:18:55 +00:00
INSTALL.md mention about x.py setup in INSTALL.md 2025-04-24 09:15:53 +03:00
LICENSE-APACHE Remove appendix from LICENCE-APACHE 2019-12-30 14:25:53 +00:00
license-metadata.json Update license metadata 2025-02-15 16:48:37 +01:00
LICENSE-MIT dist: Re-work how we describe the licence of Rust in our distributions 2024-12-09 10:18:55 +00:00
package-lock.json tidy: use a lockfile for js tools instead of npx 2025-07-19 14:44:15 -05:00
package.json tidy: use a lockfile for js tools instead of npx 2025-07-19 14:44:15 -05:00
README.md Update Rust Foundation links in Readme 2025-03-16 19:03:40 -07:00
RELEASES.md Add a few missed entries 2025-08-06 13:57:36 +01:00
REUSE.toml REUSE.toml: add new package.json and package-lock.json 2025-07-19 14:44:16 -05:00
rust-bors.toml Add approval blocking labels for new bors 2025-07-19 21:30:12 +02:00
rustfmt.toml Rename tests/codegen into tests/codegen-llvm 2025-07-22 14:28:48 +02:00
triagebot.toml Make I-miscompile imply I-prioritize 2025-08-12 08:26:11 +07:00
typos.toml setup CI and tidy to use typos for spellchecking and fix few typos 2025-07-03 10:51:06 +03:00
x Look for python3 first on MacOS, not py 2025-02-13 10:24:54 -05:00
x.ps1 use & instead of start-process in x.ps1 2023-12-09 09:46:16 -05:00
x.py Reformat Python code with ruff 2024-12-04 23:03:44 +01:00

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