global-context depends on rand-std

[vorot93]

Uses thread_rng which is only available with rand/std / rand-std enabled.

[real-or-random]

Oh yes, it seems we missed this...

[apoelstra]

Can you also add global-context to the features list of the no_std_test crate?

Unfortunate that it's such a PITA to test a feature matrix with no-std..

[vorot93]

@apoelstra done

[elichai]

Can you also add global-context to the features list of the no_std_test crate?

Unfortunate that it's such a PITA to test a feature matrix with no-std..

I don't get it. the global context will not work in the no-std tests, as it uses std :)

[apoelstra]

Oh, derp, I was confused.

How can we test this then?

[apoelstra]

To be clear, I am asking for a cargo invocation that will fail without this PR.

[elichai]

To be clear, I am asking for a cargo invocation that will fail without this PR.

gotcha,
so the problem here is that we have rand with all features as a dev-dependency, meaning that all tests enable the std feature of rand

rust-secp256k1/Cargo.toml

Line 44 in 6511fad

rand = "0.6"

I see 2 ways to write such a test if we want:

1. Add another crate that depends on secp and will do it.
2. Stop using thread_rng for tests and disable default-features for rand in the dev-dependencies.
   2.a. We can replace thread_rng with a simple Pcg32 rng seeding it either deterministically with a hard coded seed or with the system time.
   2.b. We can hard code keys in tests so we don't need any randomness.

[elichai]

The diff for 2.a is basically: https://gist.github.com/elichai/dbbb0360dd0a6a6180a2e749588a05f9

[apoelstra]

Thanks!

I think any of those options is too much work and it's fine to accept this PR as is (but @vorot93 can you drop the extra commit testing with no_std? I was confused and wrong to ask for that).

[vorot93]

@apoelstra done

[apoelstra]

I just removed the commits directly (sorry if that was too invasive). Will merge after CI passes.

[apoelstra]

ack.

Merging; travis has passed but github is waiting for yet-unmerged workflows to be executed.