Crate snapbox

Snapshot testing toolbox

When you have to treat your tests like pets, instead of cattle

snapbox is a snapshot-testing toolbox that is ready to use for verifying output from

• Function return values
• CLI stdout/stderr
• Filesystem changes

It is also flexible enough to build your own test harness like trycmd.

Which tool is right

• cram: End-to-end CLI snapshotting agnostic of any programming language
  • See also scrut
• trycmd: For running a lot of blunt tests (limited test predicates)
  • Particular attention is given to allow the test data to be pulled into documentation, like with mdbook
• tryfn: For running a lot of simple input/output tests
• snapbox: When you want something like trycmd in one off cases or you need to customize trycmds behavior.
• assert_cmd + assert_fs: Test cases follow a certain pattern but special attention is needed in how to verify the results.
• Hand-written test cases: for peculiar circumstances

Getting Started

Testing Functions:

• assert_data_eq! for quick and dirty snapshotting

Testing Commands:

• cmd::Command: Process spawning for testing of non-interactive commands
• cmd::OutputAssert: Assert the state of a Command’s Output.

Testing Filesystem Interactions:

• dir::DirRoot: Working directory for tests
• Assert: Diff a directory against files present in a pattern directory

You can also build your own version of these with the lower-level building blocks these are made of.

Feature Flags

• detect-encoding — Smarter binary file detection
• dir — Snapshotting of directories
• path — Deprecated since 0.5.11, replaced with dir
• cmd — Snapshotting of commands
• examples — Building of examples for snapshotting
• regex — Regex text substitutions
• json — Snapshotting of json
• term-svg — Snapshotting of term styling
• structured-data — Snapshotting of structured data
• debug — Extra debugging information

Default Feature Flags

• diff (enabled by default) — Fancy diffs on failure
• color — Colored output support
• color-auto (enabled by default) — Auto-detect whether to use colors

Examples

assert_data_eq!

snapbox::assert_data_eq!("Hello many people!", "Hello [..] people!");

Assert

let actual = "...";
snapbox::Assert::new()
    .action_env("SNAPSHOTS")
    .eq(actual, snapbox::file!["help_output_is_clean.txt"]);

Re-exports

pub use assert::Assert;

pub use data::Data;

pub use data::IntoData;

pub use data::IntoJson;json

pub use data::ToDebug;

pub use filter::RedactedValue;

pub use filter::Redactions;

Modules

assert

cmd

Run commands and assert on their behavior

data

actual and expected Data for testing code

dir

Initialize working directories and assert on how they’ve changed

filter

Filter actual or expected Data

prelude

Easier access to common traits

report

Utilities to report test results to users

utils

Macros

assert_data_eq

Check if a value is the same as an expected value

file

Declare an expected value for an assert from a file

str

Declare an expected value from within Rust source

Functions

assert_subset_eqdir

Check if a path matches the content of another path, recursively

assert_subset_matchesdir

Check if a path matches the pattern of another path, recursively