Test.Hspec.Expectations

Introductory documentation: https://github.com/hspec/hspec-expectations#readme

Setting expectations

type Expectation = Assertion

expectationFailure :: HasCallStack => String -> Expectation

shouldBe :: (HasCallStack, Show a, Eq a) => a -> a -> Expectation infix 1

actual `shouldBe` expected sets the expectation that actual is equal to expected.

shouldSatisfy :: (HasCallStack, Show a) => a -> (a -> Bool) -> Expectation infix 1

v `shouldSatisfy` p sets the expectation that p v is True.

shouldStartWith :: (HasCallStack, Show a, Eq a) => [a] -> [a] -> Expectation infix 1

list `shouldStartWith` prefix sets the expectation that list starts with prefix,

shouldEndWith :: (HasCallStack, Show a, Eq a) => [a] -> [a] -> Expectation infix 1

list `shouldEndWith` suffix sets the expectation that list ends with suffix,

shouldContain :: (HasCallStack, Show a, Eq a) => [a] -> [a] -> Expectation infix 1

list `shouldContain` sublist sets the expectation that sublist is contained, wholly and intact, anywhere in list.

shouldMatchList :: (HasCallStack, Show a, Eq a) => [a] -> [a] -> Expectation infix 1

xs `shouldMatchList` ys sets the expectation that xs has the same elements that ys has, possibly in another order

shouldReturn :: (HasCallStack, Show a, Eq a) => IO a -> a -> Expectation infix 1

action `shouldReturn` expected sets the expectation that action returns expected.

shouldNotBe :: (HasCallStack, Show a, Eq a) => a -> a -> Expectation infix 1

actual `shouldNotBe` notExpected sets the expectation that actual is not equal to notExpected

shouldNotSatisfy :: (HasCallStack, Show a) => a -> (a -> Bool) -> Expectation infix 1

v `shouldNotSatisfy` p sets the expectation that p v is False.

shouldNotContain :: (HasCallStack, Show a, Eq a) => [a] -> [a] -> Expectation infix 1

list `shouldNotContain` sublist sets the expectation that sublist is not contained anywhere in list.

shouldNotReturn :: (HasCallStack, Show a, Eq a) => IO a -> a -> Expectation infix 1

action `shouldNotReturn` notExpected sets the expectation that action does not return notExpected.

Expecting exceptions

shouldThrow :: (HasCallStack, Exception e) => IO a -> Selector e -> Expectation infix 1

action `shouldThrow` selector sets the expectation that action throws an exception. The precise nature of the expected exception is described with a Selector.

Selecting exceptions

type Selector a = a -> Bool

A Selector is a predicate; it can simultaneously constrain the type and value of an exception.

Predefined type-based selectors

There are predefined selectors for some standard exceptions. Each selector is just const True with an appropriate type.

anyException :: Selector SomeException

anyErrorCall :: Selector ErrorCall

anyIOException :: Selector IOException

anyArithException :: Selector ArithException

Combinators for defining value-based selectors

Some exceptions (most prominently ErrorCall) have no Eq instance. Selecting a specific value would require pattern matching.

For such exceptions, combinators that construct selectors are provided. Each combinator corresponds to a constructor; it takes the same arguments, and has the same name (but starting with a lower-case letter).

errorCall :: String -> Selector ErrorCall

Re-exports

type HasCallStack = ?callStack :: CallStack

Request a CallStack.

NOTE: The implicit parameter ?callStack :: CallStack is an implementation detail and should not be considered part of the CallStack API, we may decide to change the implementation in the future.

Since: base-4.9.0.0