Struct Mismatch 

pub struct Mismatch { /* private fields */ }

The error returned by Snapshot::check when the snapshot does not match the expected text.

A Mismatch owns the computed Diff. Its Display prints a unified diff — - lines were expected, + lines were produced — suitable for surfacing straight through a failing test’s panic message.

Examples

use test_lang::Snapshot;

let err = Snapshot::new("actual").check("expected").unwrap_err();
// `-expected` was wanted; `+actual` is what the stage produced.
assert!(err.to_string().contains("-expected"));
assert!(err.to_string().contains("+actual"));

Implementations

impl Mismatch

pub fn diff(&self) -> &Diff

The line-level diff between the expected text and the snapshot.

Use this to inspect the mismatch programmatically instead of parsing the rendered string — for example, to count how many lines changed.

Examples

use test_lang::{Change, Snapshot};

let err = Snapshot::new("a\nb").check("a\nB").unwrap_err();
let edits = err
    .diff()
    .changes()
    .filter(|(c, _)| *c != Change::Equal)
    .count();
assert_eq!(edits, 2); // one deletion, one insertion

Trait Implementations

impl Clone for Mismatch

fn clone(&self) -> Mismatch

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Mismatch

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Mismatch

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for Mismatch

impl Error for Mismatch

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

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

Provides type-based access to context intended for error reports.

impl PartialEq for Mismatch

fn eq(&self, other: &Mismatch) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for Mismatch