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