Tests a property and prints the results to stdout.

Args specifies arguments to the QuickCheck driver

Result represents the test result

The default test arguments

Tests a property, using test arguments, and prints the results to stdout.

Tests a property, using test arguments, produces a test result, and prints the results to stdout.

Tests a property, produces a test result, and prints the results to stdout.

Tests a property and prints the results and all test cases generated to stdout. This is just a convenience function that means the same as quickCheck . verbose.

Tests a property, using test arguments, and prints the results and all test cases generated to stdout. This is just a convenience function that combines quickCheckWith and verbose.

Tests a property, using test arguments, produces a test result, and prints the results and all test cases generated to stdout. This is just a convenience function that combines quickCheckWithResult and verbose.

Tests a property, produces a test result, and prints the results and all test cases generated to stdout. This is just a convenience function that combines quickCheckResult and verbose.

Test all properties in the current module. The name of the property must begin with prop_. Polymorphic properties will be defaulted to Integer. Returns True if all tests succeeded, False otherwise.

To use quickCheckAll, add a definition to your module along the lines of

return []
runTests = $quickCheckAll

and then execute runTests.

Note: the bizarre return [] in the example above is needed on GHC 7.8; without it, quickCheckAll will not be able to find any of the properties. For the curious, the return [] is a Template Haskell splice that makes GHC insert the empty list of declarations at that point in the program; GHC typechecks everything before the return [] before it starts on the rest of the module, which means that the later call to quickCheckAll can see everything that was defined before the return []. Yikes!

Test all properties in the current module. This is just a convenience function that combines quickCheckAll and verbose.

verboseCheckAll has the same issue with scoping as quickCheckAll: see the note there about return [].

Test all properties in the current module, using a custom quickCheck function. The same caveats as with quickCheckAll apply.

$forAllProperties has type (Property -> IO Result) -> IO Bool. An example invocation is $forAllProperties quickCheckResult, which does the same thing as $quickCheckAll.

forAllProperties has the same issue with scoping as quickCheckAll: see the note there about return [].

Test a polymorphic property, defaulting all type variables to Integer.

Invoke as $(polyQuickCheck 'prop), where prop is a property. Note that just evaluating quickCheck prop in GHCi will seem to work, but will silently default all type variables to ()!

$(polyQuickCheck 'prop) means the same as quickCheck $(monomorphic 'prop). If you want to supply custom arguments to polyQuickCheck, you will have to combine quickCheckWith and monomorphic yourself.

If you want to use polyQuickCheck in the same file where you defined the property, the same scoping problems pop up as in quickCheckAll: see the note there about return [].

Test a polymorphic property, defaulting all type variables to Integer. This is just a convenience function that combines verboseCheck and monomorphic.

If you want to use polyVerboseCheck in the same file where you defined the property, the same scoping problems pop up as in quickCheckAll: see the note there about return [].

Monomorphise an arbitrary property by defaulting all type variables to Integer.

For example, if f has type Ord a => [a] -> [a] then $(monomorphic 'f) has type [Integer] -> [Integer].

If you want to use monomorphic in the same file where you defined the property, the same scoping problems pop up as in quickCheckAll: see the note there about return [].

A generator for values of type a.

Generates a random element in the given inclusive range.

Randomly uses one of the given generators. The input list must be non-empty.

Chooses one of the given generators, with a weighted random distribution. The input list must be non-empty.

Generates one of the given values. The input list must be non-empty.

Takes a list of elements of increasing size, and chooses among an initial segment of the list. The size of this initial segment increases with the size parameter. The input list must be non-empty.

Used to construct generators that depend on the size parameter.

Overrides the size parameter. Returns a generator which uses the given size instead of the runtime-size parameter.

Adjust the size parameter, by transforming it with the given function.

Generates a value that satisfies a predicate.

Tries to generate a value that satisfies a predicate.

Generates a list of random length. The maximum length depends on the size parameter.

Generates a non-empty list of random length. The maximum length depends on the size parameter.

Generates a list of the given length.

Generates an infinite list.

Generates a random permutation of the given list.

Generates a random subsequence of the given list.

Generates a list of a given length.

Generates an ordered list.

Generate an infinite list.

Run a generator. The size passed to the generator is always 30; if you want another size then you should explicitly use resize.

Generates some example values and prints them to stdout.

Generates some example values.

Random generation and shrinking of values.

Used for random generation of functions.

If you are using a recent GHC, there is a default definition of coarbitrary using genericCoarbitrary, so if your type has a Generic instance it's enough to say

instance CoArbitrary MyType

You should only use genericCoarbitrary for data types where equality is structural, i.e. if you can't have two different representations of the same value. An example where it's not safe is sets implemented using binary search trees: the same set can be represented as several different trees. Here you would have to explicitly define coarbitrary s = coarbitrary (toList s).

Generates an integral number. The number can be positive or negative and its maximum absolute value depends on the size parameter.

Generates a natural number. The number's maximum value depends on the size parameter.

Generates a fractional number. The number can be positive or negative and its maximum absolute value depends on the size parameter.

Generates an integral number from a bounded domain. The number is chosen from the entire range of the type, but small numbers are generated more often than big numbers. Inspired by demands from Phil Wadler.

Generates an integral number. The number is chosen uniformly from the entire range of the type. You may want to use arbitrarySizedBoundedIntegral instead.

Generates an element of a bounded type. The element is chosen from the entire range of the type.

Generates an element of a bounded enumeration.

Generic CoArbitrary implementation.

Shrink a term to any of its immediate subterms, and also recursively shrink all subterms.

All immediate subterms of a term.

Recursively shrink all immediate subterms.

Returns no shrinking alternatives.

Shrink a list of values given a shrinking function for individual values.

Shrink an integral number.

Shrink a fraction.

Shrink a fraction, but only shrink to integral values.

Modifies a generator using an integer seed.

A coarbitrary implementation for integral numbers.

A coarbitrary implementation for real numbers.

coarbitrary helper for lazy people :-).

A coarbitrary implementation for enums.

Combine two generator perturbing functions, for example the results of calls to variant or coarbitrary.

Blind x: as x, but x does not have to be in the Show class.

Fixed x: as x, but will not be shrunk.

Ordered xs: guarantees that xs is ordered.

NonEmpty xs: guarantees that xs is non-empty.

Positive x: guarantees that x > 0.

NonZero x: guarantees that x /= 0.

NonNegative x: guarantees that x >= 0.

Large x: by default, QuickCheck generates Ints drawn from a small range. Large Int gives you values drawn from the entire range instead.

Small x: generates values of x drawn from a small range. The opposite of Large.

Smart _ x: tries a different order when shrinking.

Shrink2 x: allows 2 shrinking steps at the same time when shrinking x

Shrinking _ x: allows for maintaining a state during shrinking.

The type of properties.

Backwards combatibility note: in older versions of QuickCheck Property was a type synonym for Gen Prop, so you could mix and match property combinators and Gen monad operations. Code that does this will no longer typecheck. However, it is easy to fix: because of the Testable typeclass, any combinator that expects a Property will also accept a Gen Property. If you have a Property where you need a Gen a, simply wrap the property combinator inside a return to get a Gen Property, and all should be well.

The class of things which can be tested, i.e. turned into a property.

Explicit universal quantification: uses an explicitly given test case generator.

Like forAll, but tries to shrink the argument for failing test cases.

Shrinks the argument to property if it fails. Shrinking is done automatically for most types. This is only needed when you want to override the default behavior.

Implication for properties: The resulting property holds if the first argument is False (in which case the test case is discarded), or if the given property holds.

Like ==, but prints a counterexample when it fails.

Do I/O inside a property. This can obviously lead to unrepeatable testcases, so use with care.

For more advanced monadic testing you may want to look at Test.QuickCheck.Monadic.

Prints out the generated testcase every time the property is tested. Only variables quantified over inside the verbose are printed.

Modifies a property so that it only will be tested once.

Considers a property failed if it does not complete within the given number of microseconds.

Disables shrinking for a property altogether.

Nondeterministic choice: p1 .&. p2 picks randomly one of p1 and p2 to test. If you test the property 100 times it makes 100 random choices.

Conjunction: p1 .&&. p2 passes if both p1 and p2 pass.

Take the conjunction of several properties.

Disjunction: p1 .||. p2 passes unless p1 and p2 simultaneously fail.

Take the disjunction of several properties.

Adds the given string to the counterexample.

Adds the given string to the counterexample.

Performs an IO action after the last failure of a property.

Performs an IO action every time a property fails. Thus, if shrinking is done, this can be used to keep track of the failures along the way.

Indicates that a property is supposed to fail. QuickCheck will report an error if it does not fail.

Attaches a label to a property. This is used for reporting test case distribution.

Labels a property with a value:

collect x = label (show x)

Conditionally labels test case.

Checks that at least the given proportion of successful test cases belong to the given class. Discarded tests (i.e. ones with a false precondition) do not affect coverage.

If a property returns Discard, the current test case is discarded, the same as if a precondition was false.

A special exception that makes QuickCheck discard the test case. Normally you should use ==>, but if for some reason this isn't possible (e.g. you are deep inside a generator), use discard instead.

Changes the maximum test case size for a property.