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//! <div align="center"> //! <img src="https://github.com/mitsuhiko/insta/blob/master/assets/logo.png?raw=true" width="250" height="250"> //! <p><strong>insta: a snapshot testing library for Rust</strong></p> //! </div> //! //! # What are snapshot tests //! //! Snapshots tests (also sometimes called approval tests) are tests that //! assert values against a reference value (the snapshot). This is similar //! to how `assert_eq!` lets you compare a value against a reference value but //! unlike simple string assertions snapshot tests let you test against complex //! values and come with comprehensive tools to review changes. //! //! Snapshot tests are particularly useful if your reference values are very //! large or change often. //! //! # What it looks like: //! //! There is a screencast that shows the entire workflow: [watch the insta //! introduction screencast](https://www.youtube.com/watch?v=rCHrMqE4JOY&feature=youtu.be) //! //! # How it operates //! //! This crate exports multiple macros for snapshot testing: //! //! - `assert_snapshot!` for comparing basic string snapshots. //! - `assert_debug_snapshot!` for comparing `Debug` outputs of values. //! - `assert_display_snapshot!` for comparing `Display` outputs of values. //! - `aasert_csv_snapshot!` for comparing CSV serialized output of //! types implementing `serde::Serialize`. (requires the `csv` feature) //! - `assert_yaml_snapshot!` for comparing YAML serialized //! output of types implementing `serde::Serialize`. //! - `assert_ron_snapshot!` for comparing RON serialized output of //! types implementing `serde::Serialize`. (requires the `ron` feature) //! - `assert_json_snapshot!` for comparing JSON serialized output of //! types implementing `serde::Serialize`. //! //! Snapshots are stored in the `snapshots` folder right next to the test file //! where this is used. The name of the file is `<module>__<name>.snap` where //! the `name` of the snapshot. Snapshots can either be explicitly named or the //! name is derived from the test name. //! //! Additionally snapshots can also be stored inline. In that case the //! [`cargo-insta`](https://crates.io/crates/cargo-insta) tool is necessary. //! See [inline snapshots](#inline-snapshots) for more information. //! //! For macros that work with `serde::Serialize` this crate also permits //! redacting of partial values. See [redactions](#redactions) for more //! information. //! //! # Example //! //! Install `insta`: //! //! Recommended way if you have `cargo-edit` installed: //! //! ```text //! $ cargo add --dev insta //! ``` //! //! Alternatively edit your `Cargo.toml` manually and add `insta` as manual //! dependency. //! //! And for an improved review experience also install `cargo-insta`: //! //! ```text //! $ cargo install cargo-insta //! ``` //! //! ```no_run //! use insta::assert_debug_snapshot; //! //! #[test] //! fn test_snapshots() { //! let value = vec![1, 2, 3]; //! assert_debug_snapshot!(value); //! } //! ``` //! //! The recommended flow is to run the tests once, have them fail and check //! if the result is okay. By default the new snapshots are stored next //! to the old ones with the extra `.new` extension. Once you are satisifed //! move the new files over. To simplify this workflow you can use //! `cargo insta review` which will let you interactively review them: //! //! ```text //! $ cargo test //! $ cargo insta review //! ``` //! //! For more information on updating see [Snapshot Updating]. //! //! [Snapshot Updating]: #snapshot-updating //! //! # Snapshot files //! //! The committed snapshot files will have a header with some meta information //! that can make debugging easier and the snapshot: //! //! ```text //! --- //! expression: "&User{id: Uuid::new_v4(), username: \"john_doe\".to_string(),}" //! source: tests/test_user.rs //! --- //! [ //! 1, //! 2, //! 3 //! ] //! ``` //! //! # Snapshot updating //! //! During test runs snapshots will be updated according to the `INSTA_UPDATE` //! environment variable. The default is `auto` which will write all new //! snapshots into `.snap.new` files if no CI is detected. //! //! `INSTA_UPDATE` modes: //! //! - `auto`: the default. `no` for CI environments or `new` otherwise //! - `always`: overwrites old snapshot files with new ones unasked //! - `unseen`: behaves like `always` for new snapshots and `new` for others //! - `new`: write new snapshots into `.snap.new` files //! - `no`: does not update snapshot files at all (just runs tests) //! //! When `new` is used as mode the `cargo-insta` command can be used to review //! the snapshots conveniently: //! //! ```text //! $ cargo install cargo-insta //! $ cargo test //! $ cargo insta review //! ``` //! //! "enter" or "a" accepts a new snapshot, "escape" or "r" rejects, //! "space" or "s" skips the snapshot for now. //! //! For more information invoke `cargo insta --help`. //! //! # Test assertions //! //! By default the tests will fail when the snapshot assertion fails. However //! if a test produces more than one snapshot it can be useful to force a test //! to pass so that all new snapshots are created in one go. //! //! This can be enabled by setting `INSTA_FORCE_PASS` to `1`: //! //! ```text //! $ INSTA_FORCE_PASS=1 cargo test --no-fail-fast //! ``` //! //! A better way to do this is to run `cargo insta test --review` which will //! run all tests with force pass and then bring up the review tool: //! //! ```text //! $ cargo insta test --review //! ``` //! //! # Named snapshots //! //! All snapshot assertion functions let you leave out the snapshot name in //! which case the snapshot name is derived from the test name (with an optional //! leading `test_` prefix removed. //! //! This works because the rust test runner names the thread by the test name //! and the name is taken from the thread name. In case your test spawns additional //! threads this will not work and you will need to provide a name explicitly. //! There are some situations in which rust test does not name or use threads. //! In these cases insta will panic with an error. The `backtrace` feature can //! be enabled in which case insta will attempt to recover the test name from //! the backtrace. //! //! Explicit snapshot naming can also otherwise be useful to be more explicit //! when multiple snapshots are tested within one function as the default //! behavior would be to just count up the snapshot names. //! //! To provide an explicit name provide the name of the snapshot as first //! argument to the macro: //! //! ```no_run //! #[test] //! fn test_something() { //! assert_snapshot!("first_snapshot", "first value"); //! assert_snapshot!("second_snapshot", "second value"); //! } //! ``` //! //! This will create two snapshots: `first_snapshot` for the first value and //! `second_snapshot` for the second value. Without explicit naming the //! snapshots would be called `something` and `something-2`. //! //! # Test Output Control //! //! Insta by default will output quite a lot of information as tests run. For //! instance it will print out all the diffs. This can be controlled by setting //! the `INSTA_OUTPUT` environment variable. The following values are possible: //! //! * `diff` (default): prints the diffs //! * `summary`: prints only summaries (name of snapshot files etc.) //! * `minimal`: like `summary` but more minimal //! * `none`: insta will not output any extra information //! //! # Redactions //! //! **Feature:** `redactions` //! //! For all snapshots created based on `serde::Serialize` output `insta` //! supports redactions. This permits replacing values with hardcoded other //! values to make snapshots stable when otherwise random or otherwise changing //! values are involved. Redactions became an optional feature in insta //! 0.11 and can be enabled with the `redactions` feature. //! //! Redactions can be defined as the third argument to those macros with //! the syntax `{ selector => replacement_value }`. //! //! The following selectors exist: //! //! - `.key`: selects the given key //! - `["key"]`: alternative syntax for keys //! - `[index]`: selects the given index in an array //! - `[]`: selects all items on an array //! - `[:end]`: selects all items up to `end` (excluding, supports negative indexing) //! - `[start:]`: selects all items starting with `start` //! - `[start:end]`: selects all items from `start` to `end` (end excluding, //! supports negative indexing). //! - `.*`: selects all keys on that depth //! - `.**`: performs a deep match (zero or more items). Can only be used once. //! //! Example usage: //! //! ```no_run //! # #[cfg(feature = "redactions")] { //! # use insta::*; use serde::Serialize; use std::collections::HashMap; //! # #[derive(Serialize)] struct Uuid; impl Uuid { fn new_v4() -> Self { Uuid } } //! #[derive(Serialize)] //! pub struct User { //! id: Uuid, //! username: String, //! extra: HashMap<String, String>, //! } //! //! assert_yaml_snapshot!(&User { //! id: Uuid::new_v4(), //! username: "john_doe".to_string(), //! extra: { //! let mut map = HashMap::new(); //! map.insert("ssn".to_string(), "123-123-123".to_string()); //! map //! }, //! }, { //! ".id" => "[uuid]", //! ".extra.ssn" => "[ssn]" //! }); //! # } //! ``` //! //! It's also possible to execute a callback that can produce a new value //! instead of hardcoding a replacement value by using the //! [`dynamic_redaction`](fn.dynamic_redaction.html) function: //! //! ```no_run //! # #[cfg(feature = "redactions")] { //! # use insta::*; use serde::Serialize; //! # #[derive(Serialize)] struct Uuid; impl Uuid { fn new_v4() -> Self { Uuid } } //! # #[derive(Serialize)] //! # pub struct User { //! # id: Uuid, //! # username: String, //! # } //! assert_yaml_snapshot!(&User { //! id: Uuid::new_v4(), //! username: "john_doe".to_string(), //! }, { //! ".id" => dynamic_redaction(|value, _| { //! // assert that the value looks like a uuid here //! "[uuid]" //! }), //! }); //! # } //! ``` //! //! # Globbing //! //! **Feature:** `glob` //! //! Sometimes it can be useful to run code against multiple input files. //! The easiest way to accomplish this is to use the `glob!` macro which //! runs a closure for each input file that matches. Before the closure //! is executed the settings are updated to set a reference to the input //! file and the appropriate snapshot suffix. //! //! Example: //! //! ```rust,ignore //! use std::fs; //! //! glob!("inputs/*.txt", |path| { //! let input = fs::read_to_string(path).unwrap(); //! assert_json_snapshot!(input.to_uppercase()); //! }); //! ``` //! //! The path to the glob macro is relative to the location of the test //! file. It uses the [`globset`](https://crates.io/crates/globset) crate //! for actual glob operations. //! //! # Inline Snapshots //! //! Additionally snapshots can also be stored inline. In that case the format //! for the snapshot macros is `assert_snapshot!(reference_value, @"snapshot")`. //! The leading at sign (`@`) indicates that the following string is the //! reference value. `cargo-insta` will then update that string with the new //! value on review. //! //! Example: //! //! ```no_run //! # use insta::*; use serde::Serialize; //! #[derive(Serialize)] //! pub struct User { //! username: String, //! } //! //! assert_yaml_snapshot!(User { //! username: "john_doe".to_string(), //! }, @""); //! ``` //! //! After the initial test failure you can run `cargo insta review` to //! accept the change. The file will then be updated automatically. //! //! # Features //! //! The following features exist: //! //! * `csv`: enables CSV support (`assert_csv_snapshot!`) //! * `ron`: enables RON support (`assert_ron_snapshot!`) //! * `redactions`: enables support for redactions //! * `glob`: enables support for globbing (`glob!`) //! //! # Settings //! //! There are some settings that can be changed on a per-thread (and thus //! per-test) basis. For more information see [settings](struct.Settings.html). //! //! # Legacy Snapshot Formats //! //! With insta 0.11 the snapshot format was improved for inline snapshots. The //! old snapshot format will continue to be available but if you want to upgrade //! them make sure the tests pass first and then run the following command //! to force a rewrite of them all: //! //! ```text //! $ cargo insta test --accept --force-update-snapshots //! ``` #[macro_use] mod macros; mod content; mod runtime; mod serialization; mod settings; mod snapshot; mod utils; #[cfg(feature = "redactions")] mod redaction; #[cfg(feature = "glob")] mod glob; #[cfg(test)] mod test; pub use crate::settings::Settings; pub use crate::snapshot::{MetaData, Snapshot}; /// Exposes some library internals. /// /// You're unlikely to want to work with these objects but they /// are exposed for documentation primarily. pub mod internals { pub use crate::content::Content; pub use crate::runtime::AutoName; pub use crate::snapshot::{MetaData, SnapshotContents}; #[cfg(feature = "redactions")] pub use crate::{ redaction::{ContentPath, Redaction}, settings::Redactions, }; } // exported for cargo-insta only #[doc(hidden)] pub use crate::{ runtime::print_snapshot_diff, snapshot::PendingInlineSnapshot, snapshot::SnapshotContents, }; // useful for redactions #[cfg(feature = "redactions")] pub use crate::redaction::dynamic_redaction; // these are here to make the macros work #[doc(hidden)] pub mod _macro_support { pub use crate::content::Content; pub use crate::runtime::{assert_snapshot, get_cargo_workspace, AutoName, ReferenceValue}; pub use crate::serialization::{serialize_value, SerializationFormat, SnapshotLocation}; #[cfg(feature = "glob")] pub use crate::glob::glob_exec; #[cfg(feature = "redactions")] pub use crate::{ redaction::Redaction, redaction::Selector, serialization::serialize_value_redacted, }; }