Stability	stable
Safe Haskell	None
Language	Haskell2010

Test.Hspec

Contents

Types
Setting expectations
Defining a spec
Pending spec items
Focused spec items
Hooks
Running a spec

Description

Hspec is a testing framework for Haskell.

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

Synopsis

type Spec = SpecWith ()
type SpecWith a = SpecM a ()
class Example e where
- type Arg e
module Test.Hspec.Expectations
it :: (HasCallStack, Example a) => String -> a -> SpecWith (Arg a)
specify :: (HasCallStack, Example a) => String -> a -> SpecWith (Arg a)
describe :: HasCallStack => String -> SpecWith a -> SpecWith a
context :: HasCallStack => String -> SpecWith a -> SpecWith a
example :: Expectation -> Expectation
parallel :: SpecWith a -> SpecWith a
sequential :: SpecWith a -> SpecWith a
runIO :: IO r -> SpecM a r
pending :: HasCallStack => Expectation
pendingWith :: HasCallStack => String -> Expectation
xit :: (HasCallStack, Example a) => String -> a -> SpecWith (Arg a)
xspecify :: (HasCallStack, Example a) => String -> a -> SpecWith (Arg a)
xdescribe :: HasCallStack => String -> SpecWith a -> SpecWith a
xcontext :: HasCallStack => String -> SpecWith a -> SpecWith a
focus :: SpecWith a -> SpecWith a
fit :: (HasCallStack, Example a) => String -> a -> SpecWith (Arg a)
fspecify :: (HasCallStack, Example a) => String -> a -> SpecWith (Arg a)
fdescribe :: HasCallStack => String -> SpecWith a -> SpecWith a
fcontext :: HasCallStack => String -> SpecWith a -> SpecWith a
type ActionWith a = a -> IO ()
before :: IO a -> SpecWith a -> Spec
before_ :: IO () -> SpecWith a -> SpecWith a
beforeWith :: (b -> IO a) -> SpecWith a -> SpecWith b
beforeAll :: HasCallStack => IO a -> SpecWith a -> Spec
beforeAll_ :: HasCallStack => IO () -> SpecWith a -> SpecWith a
beforeAllWith :: HasCallStack => (b -> IO a) -> SpecWith a -> SpecWith b
after :: ActionWith a -> SpecWith a -> SpecWith a
after_ :: IO () -> SpecWith a -> SpecWith a
afterAll :: HasCallStack => ActionWith a -> SpecWith a -> SpecWith a
afterAll_ :: HasCallStack => IO () -> SpecWith a -> SpecWith a
around :: (ActionWith a -> IO ()) -> SpecWith a -> Spec
around_ :: (IO () -> IO ()) -> SpecWith a -> SpecWith a
aroundWith :: (ActionWith a -> ActionWith b) -> SpecWith a -> SpecWith b
aroundAll :: HasCallStack => (ActionWith a -> IO ()) -> SpecWith a -> Spec
aroundAll_ :: HasCallStack => (IO () -> IO ()) -> SpecWith a -> SpecWith a
aroundAllWith :: HasCallStack => (ActionWith a -> ActionWith b) -> SpecWith a -> SpecWith b
mapSubject :: (b -> a) -> SpecWith a -> SpecWith b
ignoreSubject :: SpecWith () -> SpecWith a
hspec :: Spec -> IO ()

Types

type Spec = SpecWith () #

A SpecWith that can be evaluated directly by the hspec function as it does not require any parameters.

type SpecWith a = SpecM a () #

A SpecWith a represents a test or group of tests that require an a value to run.

In the common case, a Spec is a SpecWith () which requires () and can thus be executed with hspec.

To supply an argument to SpecWith tests to turn them into Spec, use functions from Test.Hspec.Core.Hooks such as around, before, mapSubject and similar.

Values of this type are created by it, describe and similar.

class Example e #

A type class for examples, that is to say, test bodies as used in it and similar functions.

Minimal complete definition

evaluateExample

Associated Types

type Arg e #

The argument type that is needed to run this Example. If Arg is (), no argument is required and the Example can be run as-is.

The value of Arg is the difference between Spec (aka SpecWith ()), which can be executed, and SpecWith a, which cannot be executed without turning it into Spec first.

To supply an argument to examples, use the functions in Test.Hspec.Core.Hooks such as around, before, mapSubject and similar.

type Arg e = ()

Instances

Instances details

Example Result

Instance details

Defined in Test.Hspec.Core.Example

Associated Types

type Arg Result
Instance details Defined in Test.Hspec.Core.Example type Arg Result = ()

Methods

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

Example Expectation

Instance details

Defined in Test.Hspec.Core.Example

Associated Types

type Arg Expectation
Instance details Defined in Test.Hspec.Core.Example type Arg Expectation = ()

Methods

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

Example Bool

Instance details

Defined in Test.Hspec.Core.Example

Associated Types

type Arg Bool
Instance details Defined in Test.Hspec.Core.Example type Arg Bool = ()

Methods

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

Example (a -> Result)

Instance details

Defined in Test.Hspec.Core.Example

Associated Types

type Arg (a -> Result)
Instance details Defined in Test.Hspec.Core.Example type Arg (a -> Result) = a

Methods

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

Example (a -> Expectation)

Instance details

Defined in Test.Hspec.Core.Example

Associated Types

type Arg (a -> Expectation)
Instance details Defined in Test.Hspec.Core.Example type Arg (a -> Expectation) = a

Methods

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

Example (a -> Bool)

Instance details

Defined in Test.Hspec.Core.Example

Associated Types

type Arg (a -> Bool)
Instance details Defined in Test.Hspec.Core.Example type Arg (a -> Bool) = a

Methods

evaluateExample :: (a -> Bool) -> Params -> (ActionWith (Arg (a -> Bool)) -> 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

Example a optionally accepts an argument Arg a, which is then given to the test body. This is useful for provisioning resources for a test which are created and cleaned up outside the test itself. See Arg for details.

Note that this function is often on the scene of nasty type errors due to GHC failing to infer the type of do notation in the test body. It can be helpful to use TypeApplications to explicitly specify the intended Example type.

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

specify is an alias for it.

describe :: HasCallStack => String -> SpecWith a -> SpecWith a #

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

context :: HasCallStack => String -> SpecWith a -> SpecWith a #

context is an alias for describe.

example :: Expectation -> Expectation Source #

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.

sequential :: SpecWith a -> SpecWith a #

sequential marks all spec items of the given spec to be evaluated sequentially.

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 itself. 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:

not executed
reported as "pending"

pending :: HasCallStack => 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 :: HasCallStack => 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 :: HasCallStack => 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 :: HasCallStack => String -> SpecWith a -> SpecWith a #

xcontext is an alias for xdescribe.

Focused spec items

During a test run, when a spec contains focused spec items, all other spec items are ignored.

focus :: SpecWith a -> SpecWith a #

focus focuses all spec items of the given spec.

Applying focus to a spec with focused spec items has no effect.

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

fit is an alias for fmap focus . it

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

fspecify is an alias for fit.

fdescribe :: HasCallStack => String -> SpecWith a -> SpecWith a #

fdescribe is an alias for fmap focus . describe

fcontext :: HasCallStack => String -> SpecWith a -> SpecWith a #

fcontext is an alias for fdescribe.

Hooks

type ActionWith a = a -> IO () #

An IO action that expects an argument of type a.

This type is what Examples are ultimately unlifted into for execution.

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 :: HasCallStack => IO a -> SpecWith a -> Spec #

Run a custom action before the first spec item.

beforeAll_ :: HasCallStack => IO () -> SpecWith a -> SpecWith a #

Run a custom action before the first spec item.

beforeAllWith :: HasCallStack => (b -> IO a) -> SpecWith a -> SpecWith b #

Run a custom action with an argument 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 :: HasCallStack => ActionWith a -> SpecWith a -> SpecWith a #

Run a custom action after the last spec item.

afterAll_ :: HasCallStack => IO () -> SpecWith a -> SpecWith a #

Run a custom action after the last spec item.

around #

Arguments

:: (ActionWith a -> IO ())	Function provided with an action to run the spec item as argument. It should return the action to actually execute the item.
-> SpecWith a	Spec to modify
-> Spec

Run a custom action before and/or after every spec item, supplying it with an argument obtained via IO.

This is useful for tasks like creating a file handle or similar resource before a test and destroying it after the test.

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.

aroundAll :: HasCallStack => (ActionWith a -> IO ()) -> SpecWith a -> Spec #

Wrap an action around the given spec.

aroundAll_ :: HasCallStack => (IO () -> IO ()) -> SpecWith a -> SpecWith a #

Wrap an action around the given spec.

aroundAllWith :: HasCallStack => (ActionWith a -> ActionWith b) -> SpecWith a -> SpecWith b #

Wrap an action around the given spec. Changes the arg type inside.

mapSubject :: (b -> a) -> SpecWith a -> SpecWith b #

Modify the subject under test.

Note that this resembles a contravariant functor on the first type parameter of SpecM. This is because the subject is passed inwards, as an argument to the spec item.

ignoreSubject :: SpecWith () -> SpecWith a #

Ignore the subject under test for a given spec.

Running a spec

hspec :: Spec -> IO () #

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

Note: hspec handles command-line options and reads config files. This is not always desirable. Use evalSpec and runSpecForest if you need more control over these aspects.