tasty-bdd-0.2.0.0: README.md

# tasty-bdd

Typed Given/When/Then scenarios for Haskell's Tasty test framework.

## User stories: write readable test scenarios

As a test author, you can express setup, an action and assertions using constructors or `do` notation. Successful assertions pass the Tasty test; failed equality assertions show structural differences.

```mermaid
flowchart LR
  Given -->|prepare input| When
  When -->|pass result| Then
  Then -->|report outcome| Tasty
```

```haskell
import Test.BDD.LanguageFree (given, then_, when_)
import Test.Tasty (defaultMain)
import Test.Tasty.Bdd ((@?=), testBehaviorF)

main :: IO ()
main = defaultMain $ testBehaviorF id "addition" $ do
    initial <- given $ pure (40 :: Int)
    when_ (pure $ initial + 2) $ then_ (@?= 42)
```

This example is compiled and run by the `example` test suite. See [scenario examples](docs/stories/scenarios.md) and the [execution model](docs/architecture/execution.md) for setup, teardown and fail-fast behavior.

## Build and contribute

```sh
nix develop --accept-flake-config
just build
just unit
just ci
```

The locked flake uses GHC 9.12.3 on x86_64 Linux. `nix flake check --accept-flake-config` runs the packaged build, tests, lint, formatting and documentation checks. Other systems have not been verified. Read the [published documentation](https://lambdasistemi.github.io/tasty-bdd/). See [development](docs/development.md) and the [Spec Kit plan](specs/001-modernization/plan.md).

## Published package

[Hackage](https://hackage.haskell.org/package/tasty-bdd) carries 0.1.0.0, 0.1.0.1, 0.1.0.2 and 0.2.0.0. GitLab history through January 2025 is retained here, including the source published in 0.1.0.1. [Version 0.1.0.2](https://hackage.haskell.org/package/tasty-bdd-0.1.0.2) was uploaded with documentation on 2026-10-01 and is tagged `v0.1.0.2`. [Version 0.2.0.0](https://hackage.haskell.org/package/tasty-bdd-0.2.0.0), uploaded on 2026-10-01 and tagged `v0.2.0.0`, renames the `when` lens to `whenAction` and releases resources when a scenario fails by exception; see the [changelog](CHANGELOG.md). See [how releases are prepared and published](docs/releases.md).

Licensed under [BSD-3-Clause](LICENSE).