[ShryukGrandhi]

Fixes #416

Checklist

• My branch is up-to-date with main branch.
• Everything works and tested on latest stable Rust.
• Coverage and Linting have been applied

Current behaviour

The datasets feature enables std_rand. The embedded toy datasets (iris, boston, digits, ...) do not use an RNG. But the generators in dataset/generator.rs (make_blobs, make_circles, make_moons) call rand::rng(), which exists only with rand/thread_rng. If you remove std_rand from datasets, cargo build --no-default-features --features datasets fails with cannot find function rng in crate rand. The test helper readers/io_testing.rs also calls rand::rng() to make temporary file names, so cargo test --features datasets cannot compile without std_rand.

New expected behaviour

• Cargo.toml: datasets = ["serde"].
• The generators get their RNG from rand_custom::get_rng_impl(None), like the other modules in the crate. With std_rand, the RNG takes its seed from OS entropy, so the output stays random as before. Without std_rand, the RNG is SmallRng with a fixed seed (or getrandom with js), so the output is the same for each call.
• TemporaryTextFile (test-only) makes its file name from the process id and an atomic counter. It does not need an OS RNG.
• New test test_generators_without_std_rand_are_reproducible. It runs only when std_rand and js are off, and it checks that the generators compile and give reproducible output in that configuration.

Change logs

Changed

• The datasets feature no longer enables std_rand. If you want non-deterministic generator output, enable std_rand together with datasets. This is in CHANGELOG.md.

Testing

• cargo build --no-default-features --features datasets (failed before the fix, passes now)
• cargo test, cargo test --features datasets, cargo test --features datasets,std_rand, cargo test --all-features: all pass
• cargo fmt --all -- --check, cargo clippy --all-features -- -Drust-2018-idioms -Dwarnings: clean

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.58%. Comparing base (9eaae9e) to head (5f661ed).
⚠️ Report is 204 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #499       +/-   ##
===========================================
+ Coverage   43.97%   85.58%   +41.60%     
===========================================
  Files          85       96       +11     
  Lines        7281     9373     +2092     
===========================================
+ Hits         3202     8022     +4820     
+ Misses       4079     1351     -2728     

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