Test.Hspec

Hspec is a testing framework for Haskell.

This is the library reference for Hspec. The User's Manual contains more in-depth documentation.

Types

type Spec = SpecWith ()

type SpecWith a = SpecM a ()

type family Arg e :: *

Instances

type Arg Bool = ()

type Arg Property = ()

type Arg Result = ()

type Arg Expectation = ()

type Arg (a -> Property) = a

type Arg (a -> Expectation) = a

class Example e

A type class for examples

Minimal complete definition

evaluateExample

Associated Types

type Arg e :: *

Instances

Example Bool

Example Property

Example Result

Example Expectation

Example (a -> Expectation)

Example (a -> Property)

Setting expectations

module Test.Hspec.Expectations

Defining a spec

describe :: String -> SpecWith a -> SpecWith a

The describe function combines a list of specs into a larger spec.

context :: String -> SpecWith a -> SpecWith a

context is an alias for describe.

it :: Example a => String -> a -> SpecWith (Arg a)

The it function creates a spec item.

A spec item consists of:

• a textual description of a desired behavior
• an example for that behavior

describe "absolute" $ do
  it "returns a positive number when given a negative number" $
    absolute (-1) == 1

specify :: Example a => String -> a -> SpecWith (Arg a)

specify is an alias for it.

example :: Expectation -> Expectation

example is a type restricted version of id. It can be used to get better error messages on type mismatches.

Compare e.g.

it "exposes some behavior" $ example $ do
  putStrLn

with

it "exposes some behavior" $ do
  putStrLn

pending :: Expectation

pending can be used to indicate that an example is pending.

If you want to textually specify a behavior but do not have an example yet, use this:

describe "fancyFormatter" $ do
  it "can format text in a way that everyone likes" $
    pending

pendingWith :: String -> Expectation

pendingWith is similar to pending, but it takes an additional string argument that can be used to specify the reason for why it's pending.

parallel :: SpecWith a -> SpecWith a

parallel marks all spec items of the given spec to be safe for parallel evaluation.

runIO :: IO r -> SpecM a r

Run an IO action while constructing the spec tree.

SpecM is a monad to construct a spec tree, without executing any spec items. runIO allows you to run IO actions during this construction phase. The IO action is always run when the spec tree is constructed (e.g. even when --dry-run is specified). If you do not need the result of the IO action to construct the spec tree, beforeAll may be more suitable for your use case.

Hooks

type ActionWith a = a -> IO ()

An IO action that expects an argument of type a

before :: IO a -> SpecWith a -> Spec

Run a custom action before every spec item.

before_ :: IO () -> SpecWith a -> SpecWith a

Run a custom action before every spec item.

beforeWith :: (b -> IO a) -> SpecWith a -> SpecWith b

Run a custom action before every spec item.

beforeAll :: IO a -> SpecWith a -> Spec

Run a custom action before the first spec item.

after :: ActionWith a -> SpecWith a -> SpecWith a

Run a custom action after every spec item.

after_ :: IO () -> SpecWith a -> SpecWith a

Run a custom action after every spec item.

afterAll :: ActionWith a -> SpecWith a -> SpecWith a

Run a custom action after the last spec item.

afterAll_ :: IO () -> SpecWith a -> SpecWith a

Run a custom action after the last spec item.

around :: (ActionWith a -> IO ()) -> SpecWith a -> Spec

Run a custom action before and/or after every spec item.

around_ :: (IO () -> IO ()) -> SpecWith a -> SpecWith a

Run a custom action before and/or after every spec item.

aroundWith :: (ActionWith a -> ActionWith b) -> SpecWith a -> SpecWith b

Run a custom action before and/or after every spec item.

Running a spec

hspec :: Spec -> IO ()

Run given spec and write a report to stdout. Exit with exitFailure if at least one spec item fails.