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 Bool = ()

type Arg Property

type Arg Property = ()

type Arg Result

type Arg Result = ()

type Arg Expectation

type Arg Expectation = ()

type Arg (a -> Property)

type Arg (a -> Property) = a

type Arg (a -> Expectation)

type Arg (a -> Expectation) = a

type Arg (a -> Bool)

type Arg (a -> Bool) = a

type Arg (a -> Result)

type Arg (a -> Result) = a

class Example e

A type class for examples

Minimal complete definition

evaluateExample

Associated Types

type Arg e :: *

Instances

Example Bool

Associated Types

type Arg Bool :: *

Methods

evaluateExample :: Bool -> Params -> (ActionWith (Arg Bool) -> IO ()) -> ProgressCallback -> IO Result

Example Property

Associated Types

type Arg Property :: *

Methods

evaluateExample :: Property -> Params -> (ActionWith (Arg Property) -> IO ()) -> ProgressCallback -> IO Result

Example Result

Associated Types

type Arg Result :: *

Methods

evaluateExample :: Result -> Params -> (ActionWith (Arg Result) -> IO ()) -> ProgressCallback -> IO Result

Example Expectation

Associated Types

type Arg Expectation :: *

Methods

evaluateExample :: Expectation -> Params -> (ActionWith (Arg Expectation) -> IO ()) -> ProgressCallback -> IO Result

Example (a -> Result)

Associated Types

type Arg (a -> Result) :: *

Methods

evaluateExample :: (a -> Result) -> Params -> (ActionWith (Arg (a -> Result)) -> IO ()) -> ProgressCallback -> IO Result

Example (a -> Bool)

Associated Types

type Arg (a -> Bool) :: *

Methods

evaluateExample :: (a -> Bool) -> Params -> (ActionWith (Arg (a -> Bool)) -> IO ()) -> ProgressCallback -> IO Result

Example (a -> Expectation)

Associated Types

type Arg (a -> Expectation) :: *

Methods

evaluateExample :: (a -> Expectation) -> Params -> (ActionWith (Arg (a -> Expectation)) -> IO ()) -> ProgressCallback -> IO Result

Example (a -> Property)

Associated Types

type Arg (a -> Property) :: *

Methods

evaluateExample :: (a -> Property) -> Params -> (ActionWith (Arg (a -> Property)) -> IO ()) -> ProgressCallback -> IO Result

Setting expectations

module Test.Hspec.Expectations

Defining a spec

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

specify is an alias for it.

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.

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

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.

Pending spec items

During a test run a pending spec item is:

1. not executed
2. reported as "pending"

pending :: Expectation

pending can be used to mark a spec item as 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 the spec item is pending.

xit :: (HasCallStack, Example a) => String -> a -> SpecWith (Arg a)

Changing it to xit marks the corresponding spec item as pending.

This can be used to temporarily disable a spec item.

xspecify :: (HasCallStack, Example a) => String -> a -> SpecWith (Arg a)

xspecify is an alias for xit.

xdescribe :: String -> SpecWith a -> SpecWith a

Changing describe to xdescribe marks all spec items of the corresponding subtree as pending.

This can be used to temporarily disable spec items.

xcontext :: String -> SpecWith a -> SpecWith a

xcontext is an alias for xdescribe.

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.

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

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.