test-span

A macro and utilities to do snapshot tests on tracing spans.

How to use

Refer to the tests for a more exhaustive list of features and behaviors:

use test_span::prelude::*;

#[test_span]
fn a_test() {
    do_something();

    // test_span provides your with three functions:
    let spans = get_spans();
    let logs = get_logs();
    // you can get both in one call
    let (spans, logs) = get_telemetry();

    // This plays well with insta snapshots:
    insta::assert_json_snapshot!(logs);
    insta::assert_json_snapshot!(spans);
}

// Test span plays well with async
#[test_span(tokio::test)]
// you can specify the span / log level
// you would like to track like this:
#[level(tracing::Level::INFO)]
async fn an_sync_test() {
    do_something_async().await;
    // You still get access to each function
    let spans = get_spans();
    let logs = get_logs();
    let (spans, logs) = get_telemetry();
}

Limitations

Spans and logs are hard to track across thread spawns. However we're providing you with a log dump you can check:

#[test_span]
fn track_across_threads() {
    std::thread::spawn(|| {
        tracing::info!("only in get_all_logs!");
    })
    .join()
    .unwrap();

    let logs = get_logs();
    // not in get_logs()
    assert!(!logs.contains_message("only in get_all_logs!");

    // get_all_logs takes a filter Level
    let all_logs = test_span::get_all_logs(&tracing::Level::INFO);
    assert!(all_logs.contains_message("only in get_all_logs!"));
}

Contributing

More information can be found in the contribution docs

License