Struct snapbox::Assert

pub struct Assert { /* private fields */ }

Snapshot assertion against a file’s contents

Useful for one-off assertions with the snapshot stored in a file

Examples

let actual = "...";
snapbox::Assert::new()
    .action_env("SNAPSHOTS")
    .matches_path(actual, "tests/fixtures/help_output_is_clean.txt");

Implementations

impl Assert

Assertions

pub fn new() -> Self

pub fn eq(&self, expected: impl Into<Data>, actual: impl Into<Data>)

Check if a value is the same as an expected value

When the content is text, newlines are normalized.

let output = "something";
let expected = "something";
snapbox::Assert::new().eq(expected, output);

pub fn matches(&self, pattern: impl Into<Data>, actual: impl Into<Data>)

Check if a value matches a pattern

Pattern syntax:

• ... is a line-wildcard when on a line by itself
• [..] is a character-wildcard when inside a line
• [EXE] matches .exe on Windows

Normalization:

• Newlines
• \ to /

let output = "something";
let expected = "so[..]g";
snapbox::Assert::new().matches(expected, output);

pub fn eq_path(&self, expected_path: impl AsRef<Path>, actual: impl Into<Data>)

Check if a value matches the content of a file

When the content is text, newlines are normalized.

let output = "something";
let expected_path = "tests/snapshots/output.txt";
snapbox::Assert::new().eq_path(output, expected_path);

pub fn matches_path(
    &self,
    pattern_path: impl AsRef<Path>,
    actual: impl Into<Data>
)

Check if a value matches the pattern in a file

Pattern syntax:

• ... is a line-wildcard when on a line by itself
• [..] is a character-wildcard when inside a line
• [EXE] matches .exe on Windows (override with Assert::substitutions)

Normalization:

• Newlines
• \ to /

let output = "something";
let expected_path = "tests/snapshots/output.txt";
snapbox::Assert::new().matches_path(expected_path, output);

impl Assert

Directory Assertions

pub fn subset_eq(
    &self,
    expected_root: impl Into<PathBuf>,
    actual_root: impl Into<PathBuf>
)

Available on crate feature path only.

pub fn subset_matches(
    &self,
    pattern_root: impl Into<PathBuf>,
    actual_root: impl Into<PathBuf>
)

Available on crate feature path only.

impl Assert

Customize Behavior

pub fn palette(self, palette: Palette) -> Self

Override the color palette

pub fn action_env(self, var_name: &str) -> Self

Read the failure action from an environment variable

pub fn action(self, action: Action) -> Self

Override the failure action

pub fn substitutions(self, substitutions: Substitutions) -> Self

Override the default Substitutions

pub fn binary(self, yes: bool) -> Self

Specify whether the content should be treated as binary or not

The default is to auto-detect

Trait Implementations

impl Clone for Assert

fn clone(&self) -> Assert

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Assert

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

Formats the value using the given formatter.

impl Default for Assert

fn default() -> Self

Returns the “default value” for a type.