stderr().is() fails due to cargo output

[steveej]

Hey, during my first attempts of writing integration tests I've stumbled upon an issue when the program is supposed to exit with an error output.

My test looks like this:

    #[test]
    fn called_without_args() {
        assert_cli::Assert::main_binary()
            .fails_with(::libc::EINVAL)
            .and()
            .stderr().is(MISSING_ARGUMENTS_OUTPUT)
            .unwrap();
    }

test integration::called_without_args ... FAILED

failures:

---- integration::called_without_args stdout ----
        thread 'integration::called_without_args' panicked at 'CLI assertion failed: `cargo run --` StdErr mismatch: diff:

+Compiling invsearch v0.1.0 (file:///.../invsearch.rs)
    Finished dev [unoptimized + debuginfo] target(s) in 0.62 secs
     Running `target/debug/invsearch`
 No arguments provided. Please provide files to parse.
', /home/steveej/.cargo/registry/src/gb.xjqchip.workers.dev-1ecc6299db9ec823/assert_cli-0.5.3/src/assert.rs:319:12
note: Run with `RUST_BACKTRACE=1` for a backtrace.

The issue is that the error outputs of cargo and the integration test are mixed and the test fails because it's not an exact match.
I know that I could just use .contains(..) instead of .is(..), but IMHO that's only a workaround.

Please let me know if I'm doing something unexpected, as this is my very first attempt of writing (integration) tests in Rust.

[killercup]

Oh, that is a very good point. That we use cargo run behind the scenes to run the main binary should only be an implementation detail. I guess this code:

https://github.com/killercup/assert_cli/blob/875c4b156b9c5015d22d00d52bc9528764e69b79/src/assert.rs#L27

should also pass --quiet to cargo.

[epage]

Something that would help in testing this and the crate all-around is to create a bin for it. It'd be handy for it to have command line flags for it to print to stdout/stderr, process stdin, process env variables, return arbitrary codes, etc.

[steveej]

Thanks @epage!