Use exit code 2 to indicate error

[sirreal]

Exit code 1 was shared to indicate both "no results" and "error." Use status code 2 to indicate errors, similar to grep's behavior.

Fixes #948

Adds integration tests for exit codes.
Adds test helper WorkDir::assert_exit_code(&self, expected_code: i32, cmd: &mut process::Command) to match arbitrary exit codes in tests.

Testing

cargo test exit_code

Manual testing

Verify that the exit code is now 2 for error:

$ cargo run -- '*' src/main.rs ; echo "Status code: $?"

    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `target/debug/rg '*' src/main.rs`
regex parse error:
    *
    ^
error: repetition operator missing expression
Status code: 2

And remains 0 when matches are found:

$ cargo run -- 'main' src/main.rs ; echo "Status code: $?"

    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `target/debug/rg main src/main.rs`
56:fn main() {
Status code: 0

And 1 for no matches:

cargo run -- 'this_does_not_match' src/main.rs ; echo "Status code: $?"


    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `target/debug/rg this_does_not_match src/main.rs`
Status code: 1

[BurntSushi]

@sirreal What do you think about adding few tests for this? We should be able to capture your manual tests in ripgrep's integration tests.

The test helpers themselves might need some additions to test this. For example, you might consider adding something similar to assert_err that lets one specifically probe the exit status code. In that code, o.status is a std::process::ExitStatus, which means it should be easy to retrieve the exit code.

[sirreal]

I was wondering about testing. I'm happy to look into that, I'll investigate soon 👍

[sirreal]

Should match any non-empty file

[sirreal]

Highly unlikely to match any file. 10 random hex digits repeated 10 times.

[sirreal]

Invalid regex.

[sirreal]

I've added some integration tests as suggested, I'd appreciate feedback.

[sirreal]

These expects can just become unwrap.

[BurntSushi]

Excellent! This is perfect as-is, thank you so much. :-)

[sirreal]

A pleasure! 🙌