Test.Extrapolate.IO

This module is part of Extrapolate, a library for generalization of counter-examples.

QuickCheck-like interface.

Documentation

check :: Testable a => a -> IO ()

Checks a property printing results on stdout

> check $ \xs -> sort (sort xs) == sort (xs::[Int])
+++ OK, passed 360 tests.

> check $ \xs ys -> xs `union` ys == ys `union` (xs::[Int])
*** Failed! Falsifiable (after 4 tests):
[] [0,0]

Generalization:
[] (x:x:_)

checkResult :: Testable a => a -> IO Bool

Check a property printing results on stdout and returning True on success.

There is no option to silence this function: for silence, you should use holds.

for :: Testable a => (WithOption a -> b) -> Int -> a -> b

Use for to configure the number of tests performed by check.

> check `for` 10080 $ \xs -> sort (sort xs) == sort (xs :: [Int])
+++ OK, passed 10080 tests.

Don't forget the dollar ($)!

withInstances :: Testable a => (WithOption a -> b) -> Instances -> a -> b

Allows the user to customize instance information available when generalized. (For advanced users.)

withBackground :: Testable a => (WithOption a -> b) -> [Expr] -> a -> b

Use withBackground to provide additional functions to appear in side-conditions.

check `withBackground` [constant "isSpace" isSpace] $ \xs -> unwords (words xs) == xs
*** Failed! Falsifiable (after 4 tests):
" "

Generalization:
' ':_

Conditional Generalization:
c:_  when  isSpace c

withConditionSize :: Testable a => (WithOption a -> b) -> Int -> a -> b

Use withConditionSize to configure the maximum condition size allowed.