`main_binary` takes ~300ms per invocation

[epage]

From @rcoh assert-rs/assert_cli#100

• assert_cli version: 0.5
• Rust version: 1.25.0
• OS and version: Ubuntu 16.04
  Unfortunately, cargo run takes at minimum about 300ms on my computer:

➜  angle-grinder git:(master) ✗ time cargo run --bin agrind -- '* | json | count' --file test_files/empty
    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `target/debug/agrind '* | json | count' --file test_files/empty`
No data
cargo run --bin agrind -- '* | json | count' --file test_files/empty  0.22s user 0.06s system 92% cpu 0.307 total

It makes it impractical to run hundreds of integration tests with assert_cli.

I'm not positive what a better way would be -- I guess running the binary in dist directly if it exists?

Workaround

See assert_cmd::cargo's docs

[epage]

From killercup: cargo issue: rust-lang/cargo#5315

[epage]

So a user can work around this in assert_cmd by accessing cargo_bin_path, etc. This causes the 300ms to only be hit once instead of on every run.

lazy_static! {
    const BIN_UNDER_TEST = assert-cmd::cargo_bin_path("bin_fixture");
}

#[test]
fn test_bin() {
    Command::new(BIN_UNDER_TEST).assert().success();
}

Should we provide an API on to simplify this?

Example

lazy_static!{
   const BIN_FIXTURE = assert_cmd::cargo_bin("bin_fixture");
}
...
println!("{:?}", BIN_FIXTURE.path());
BIN_FIXTURE.cmd().arg("stdout", 42).unwrap();

[zetok]

Additions to API aren't needed, but docs that would point out this functionality would be really helpful. Since right now one needs to go to the issue tracker of the crate to find the solution, which is suboptimal.

As for why an additional API is not needed – e.g. regex crate doesn't have an additional API for creating a static regexp, but it has a great documentation where it shows on the "main" page of its docs an example on how to use lazy_static to reduce unnecessary computations. It's nice.

Also, a working example, freshly ~copypasted from a test for anyone else who's interested:

use std::path::PathBuf;

lazy_static! {
    static ref BIN_PATH: PathBuf = assert_cmd::cargo::main_binary_path().unwrap();
}

#[test]
fn test_bin() {
    Command::new(&*BIN_PATH).assert().success();
}

[epage]

As for why an additional API is not needed – e.g. regex crate doesn't have an additional API for creating a static regexp

The difference is the main purpose of this crate is running programs. Its a bit of a wart in the API to have functions that provide paths to programs you could run. It'd be nice if Command supported clone.

[epage]

I think at this point this is mostly kept open to track and be aware of the slow down. We have workarounds but thats all they are.

[killercup]

Have we ever measured this again with newer cargo versions? I recall them adding some caching for this, too.

…

On Sun, 7 Oct 2018, 00:56 Ed Page, ***@***.***> wrote: I think at this point this is mostly kept open to track and be aware of the slow down. We have workarounds but thats all they are. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#6 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AABOX9lsA8jsePQJ2AkErzGU37rEu00Xks5uiTUogaJpZM4UQkyB> .