Struct Trace 

pub struct Trace { /* private fields */ }

A scoped collector of in-test breadcrumbs.

Construct one at the top of a test; every TestError built before it is dropped carries a snapshot of the breadcrumbs recorded so far, and renders them in the failure output.

use test_better_core::Trace;

let mut trace = Trace::new();
trace.step("connecting to db");
trace.kv("db_url", "postgres://localhost/test");
trace.step("running the query");
// If an assertion fails here, these three breadcrumbs are attached to the
// resulting `TestError` and shown, in order, in the rendered failure.

Dropping the Trace ends the scope. Nested traces compose: an inner Trace::new() displaces the outer trace’s entries and restores them on drop, so the outer trace resumes intact.

Implementations

impl Trace

pub fn new() -> Trace

Starts a trace, collecting breadcrumbs until it is dropped.

pub fn step(&mut self, message: impl Into<Cow<'static, str>>)

Records a narrative step.

pub fn kv(&mut self, key: impl Into<Cow<'static, str>>, value: impl Display)

Records a key/value breadcrumb, rendering value with Display now, so the breadcrumb is not tied to the value’s lifetime.

pub fn entries(&self) -> Vec<TraceEntry>

The breadcrumbs recorded in the active trace so far, oldest first.

Trait Implementations

impl Default for Trace

fn default() -> Trace

Returns the “default value” for a type.

impl Drop for Trace

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.