75 lines
3.0 KiB
Markdown
75 lines
3.0 KiB
Markdown
<div align="center">
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<img src="https://github.com/mitsuhiko/insta/blob/master/assets/logo.png?raw=true" width="250" height="250">
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<p><strong>insta: a snapshot testing library for Rust</strong></p>
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</div>
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[](https://crates.io/crates/insta)
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[](https://github.com/mitsuhiko/insta/blob/master/LICENSE)
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[](https://docs.rs/insta)
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[](https://marketplace.visualstudio.com/items?itemName=mitsuhiko.insta)
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## Introduction
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Snapshots tests (also sometimes called approval tests) are tests that
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assert values against a reference value (the snapshot). This is similar
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to how `assert_eq!` lets you compare a value against a reference value but
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unlike simple string assertions, snapshot tests let you test against complex
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values and come with comprehensive tools to review changes.
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Snapshot tests are particularly useful if your reference values are very
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large or change often.
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## Example
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```rust
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#[test]
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fn test_hello_world() {
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insta::assert_debug_snapshot!(vec![1, 2, 3]);
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}
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```
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Curious? There is a screencast that shows the entire workflow: [watch the insta
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introduction screencast](https://www.youtube.com/watch?v=rCHrMqE4JOY&feature=youtu.be).
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Or if you're not into videos, read the [5 minute introduction](https://insta.rs/docs/quickstart/).
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Insta also supports inline snapshots which are stored right in your source file
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instead of separate files. This is accomplished by the companion
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[cargo-insta](https://github.com/mitsuhiko/insta/tree/master/cargo-insta) tool.
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## Editor Support
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For looking at `.snap` files there is a [vscode extension](https://github.com/mitsuhiko/insta/tree/master/vscode-insta)
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which can syntax highlight snapshot files, review snapshots and more. It can be installed from the
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marketplace: [view on marketplace](https://marketplace.visualstudio.com/items?itemName=mitsuhiko.insta).
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## Diffing
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Insta uses [`similar`](https://github.com/mitsuhiko/similar) for all its diffing
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operations. You can use it independently of insta. You can use the
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[`similar-asserts`](https://github.com/mitsuhiko/similar-asserts) crate to get
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inline diffs for the standard `assert_eq!` macro to achieve insta like diffs
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for regular comparisons:
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```rust
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use similar_asserts::assert_eq;
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fn main() {
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let reference = vec![1, 2, 3, 4];
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assert_eq!(reference, (0..4).collect::<Vec<_>>());
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}
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```
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## Sponsor
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If you like the project and find it useful you can [become a
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sponsor](https://github.com/sponsors/mitsuhiko).
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## License and Links
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- [Project Website](https://insta.rs/)
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- [Documentation](https://docs.rs/insta/)
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- [Issue Tracker](https://github.com/mitsuhiko/insta/issues)
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- License: [Apache-2.0](https://github.com/mitsuhiko/insta/blob/master/LICENSE)
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