Invert status output of tests (suffix instead of prefix)

[emidoots]

As it is currently running some tests looks like this:

test vec4::eq_1 ... ok
test vec4::is_zero_0 ... ok
test vec4::fmt_0 ... ok
test vec4::length_sq_0 ... ok
test vec4::is_nan_0 ... ok
test vec4::lerp_0 ... ok
test vec4::length_0 ... ok
test vec4::max_0 ... ok
test vec4::mul_0 ... ok
test vec4::mul_scalar_0 ... ok
test vec4::min_0 ... ok
test vec4::one_1 ... ok
test vec4::one_0 ... ok
test vec4::neg_0 ... ok
test vec4::partial_cmp_0 ... failed
test vec4::normalize_0 ... ok
test vec4::sub_0 ... ok
test vec4::project_0 ... ok
test vec4::round_0 ... ok
test vec4::zero_0 ... failed
test vec4::sub_scalar_0 ... ok

test result: ok. 19 passed; 2 failed; 0 ignored; 0 measured

Because the names are not the most important aspect of the message (the ok/failure status is), I believe it may make sense to invert the status output like so:

[ok] test vec4::eq_1
[ok] test vec4::is_zero_0
[ok] test vec4::fmt_0
[ok] test vec4::length_sq_0
[ok] test vec4::is_nan_0
[ok] test vec4::lerp_0
[ok] test vec4::length_0
[ok] test vec4::max_0
[ok] test vec4::mul_0
[ok] test vec4::mul_scalar_0
[ok] test vec4::min_0
[ok] test vec4::one_1
[ok] test vec4::one_0
[ok] test vec4::neg_0
[failed] test vec4::partial_cmp_0
[ok] test vec4::normalize_0
[ok] test vec4::sub_0
[ok] test vec4::project_0
[ok] test vec4::round_0
[failed] test vec4::zero_0
[ok] test vec4::sub_scalar_0

test result: ok. 19 passed; 2 failed; 0 ignored; 0 measured

Note that:

1. This makes it easier to identify which tests failed or not, because the status is not offset by a name of arbitrary length.
2. This might not make sense if printing the test name is important prior to the status (e.g. if the output is not fully buffered, or if test programs may sometimes hang and the testing framework can't catch this).

Moved here from rust-lang/cargo#1985

[alexispurslane]

👍 I agree, and I'd be willing to implement this.

[steveklabnik]

👍

[viraptor]

This will be pretty bad for accidental infinite loops. It's already required to turn off multithreaded testing to figure out which test is even hanging. Unless there's also some way to add test timeouts by default, switching the output order will be a pain.

[brson]

Seems like a worthy idea. Let's see if the tools team wants to consider it.

[nagisa]

The name can be printed “before” status (in time as opposed to space) by using some escape sequence tricks to reset the cursor to the original position (i.e. in the similar manner progress bars are implemented)

[viraptor]

Is this still a problem, now that cargo test uses green / red colours in the output? (if I understand correctly, the original feature was about easy visibility)

[nrc]

We discussed this at the dev-tools meeting. Our verdict was that this should remain P-low. There was some discussion about printing the test name before a test is run (this is useful if a test segfaults, then you know which test is to blame) - which is #30047.

On this issue, we decided we should not change things because there is low benefit (now that ok/fail is coloured) and there is always a cost to change.