QCheck.Gen
type 'a t = Random.State.t -> 'a
A random generator for values of type 'a.
type 'a sized = int -> Random.State.t -> 'a
Random generator with a size bound.
val return : 'a -> 'a t
Create a constant generator.
Monadic bind for writing dependent generators. First generates an 'a
and then passes it to the given function, to generate a 'b
.
Infix operator for composing a function generator and an argument generator into a result generator.
map f g
transforms a generator g
by applying f
to each generated element.
map2 f g1 g2
transforms two generators g1
and g2
by applying f
to each pair of generated elements.
map3 f g1 g2 g3
transforms three generators g1
, g2
, and g3
by applying f
to each triple of generated elements.
map_keep_input f g
transforms a generator g
by applying f
to each generated element. Returns both the generated element from g
and the output from f
.
val oneofl : 'a list -> 'a t
Constructs a generator that selects among a given list of values.
val oneofa : 'a array -> 'a t
Constructs a generator that selects among a given array of values.
Constructs a generator that selects among a given list of generators. Each of the given generators are chosen based on a positive integer weight.
val frequencyl : (int * 'a) list -> 'a t
Constructs a generator that selects among a given list of values. Each of the given values are chosen based on a positive integer weight.
val frequencya : (int * 'a) array -> 'a t
Constructs a generator that selects among a given array of values. Each of the array entries are chosen based on a positive integer weight.
val shuffle_a : 'a array -> unit t
Shuffles the array in place.
val shuffle_l : 'a list -> 'a list t
Creates a generator of shuffled lists.
val shuffle_w_l : (int * 'a) list -> 'a list t
Creates a generator of weighted shuffled lists. A given list is shuffled on each generation according to the weights of its elements. An element with a larger weight is more likely to be at the front of the list than an element with a smaller weight. If we want to pick random elements from the (head of) list but need to prioritize some elements over others, this generator can be useful.
Example: given a weighted list [1, "one"; 5, "five"; 10, "ten"]
, the generator is more likely to generate ["ten"; "five"; "one"]
or ["five"; "ten"; "one"]
than ["one"; "ten"; "five"]
because "ten" and "five" have larger weights than "one".
val range_subset : size:int -> int -> int -> int array t
range_subset ~size:k low high
generates an array of length k
of sorted distinct integers in the range low..high
(included).
Complexity O(k log k), drawing k
random integers.
val array_subset : int -> 'a array -> 'a array t
array_subset k arr
generates a sub-array of k
elements at distinct positions in the input array arr
, in the same order.
Complexity O(k log k), drawing k
random integers.
val unit : unit t
The unit generator.
val bool : bool t
The boolean generator.
val float : float t
Generates floating point numbers.
val pfloat : float t
Generates positive floating point numbers (0. included).
val nfloat : float t
Generates negative floating point numbers. (-0. included)
val float_bound_inclusive : float -> float t
float_bound_inclusive bound
returns a random floating-point number between 0 and bound
(inclusive). If bound
is negative, the result is negative or zero. If bound
is 0, the result is 0.
val float_bound_exclusive : float -> float t
float_bound_exclusive bound
returns a random floating-point number between 0 and bound
(exclusive). If bound
is negative, the result is negative or zero.
val float_range : float -> float -> float t
float_range low high
generates floating-point numbers within low
and high
(inclusive)
val (--.) : float -> float -> float t
Synonym for float_range
val nat : int t
Generates small natural numbers.
val big_nat : int t
Generates natural numbers, possibly large.
val neg_int : int t
Generates non-strictly negative integers (0 included).
val pint : int t
Generates non-strictly positive integers uniformly (0 included).
val int : int t
Generates integers uniformly.
val small_nat : int t
Small integers (< 100)
val small_int : int t
Small UNSIGNED integers, for retrocompatibility.
val int_bound : int -> int t
Uniform integer generator producing integers between 0
and bound
(inclusive). For bound < 2^{30} - 1
uses Random.State.int
for integer generation.
val int_range : int -> int -> int t
Uniform integer generator producing integers within low,high
(inclusive).
graft_corners gen l ()
makes a new generator that enumerates the corner cases in l
and then behaves like g
.
val ui32 : int32 t
Generates (unsigned) int32
values.
val ui64 : int64 t
Generates (unsigned) int64
values.
Builds a list generator from an element generator. List size is generated by nat
.
Builds a list generator from a (non-negative) size generator and an element generator.
list_repeat i g
builds a list generator from exactly i
elements generated by g
.
Builds an array generator from an element generator. Array size is generated by nat
.
Builds an array generator from a (non-negative) size generator and an element generator.
array_repeat i g
builds an array generator from exactly i
elements generated by g
.
gen1
, then gen2
, then ...val char : char t
Generates characters upto character code 255.
val printable : char t
Generates printable ascii characters - either '\n' or in the range 32 to 126, inclusive
val numeral : char t
Generates numeral characters.
val char_range : char -> char -> char t
Generates chars between the two bounds, inclusive. Example: char_range 'a' 'z'
for all lower case ascii letters.
Builds a bytes generator from a (non-negative) size generator. Accepts an optional character generator (the default is char
).
val bytes_small : bytes t
Builds a bytes generator using the given character generator, length is small_nat
.
Builds a string generator from a (non-negative) size generator. Accepts an optional character generator (the default is char
).
Builds a string generator. String size is generated by nat
. Accepts an optional character generator (the default is char
). See also string_of
and string_readable
for versions without optional parameters.
val string_readable : string t
val string_small : string t
Builds a string generator using the given character generator, length is small_nat
.
Generate a result from Ok g
, an error from Error e
Creates a generator from a size-bounded generator by first generating a size using nat
and passing the result to the size-bounded generator.
Creates a generator from a size-bounded generator by first generating a size using the integer generator and passing the result to the size-bounded generator.
Parametrized fixpoint combinator for generating recursive values.
The fixpoint is parametrized over an arbitrary state ('a), and the fixpoint computation may change the value of this state in the recursive calls.
In particular, this can be used for size-bounded generators ('a is int). The passed size-parameter should decrease to ensure termination.
Example:
type tree = Leaf of int | Node of tree * tree
let leaf x = Leaf x
let node x y = Node (x,y)
let g = QCheck.Gen.(sized @@ fix
(fun self n -> match n with
| 0 -> map leaf nat
| n ->
frequency
[1, map leaf nat;
2, map2 node (self (n/2)) (self (n/2))]
))
val nat_split2 : int -> (int * int) t
nat_split2 n
generates pairs (n1, n2)
of natural numbers with n1 + n2 = n
.
This is useful to split sizes to combine sized generators.
val pos_split2 : int -> (int * int) t
pos_split2 n
generates pairs (n1, n2)
of strictly positive (nonzero) natural numbers with n1 + n2 = n
.
val nat_split : size:int -> int -> int array t
nat_split ~size:k n
generates k
-sized arrays n1,n2,..nk
of natural numbers in [0;n]
with n1 + n2 + ... + nk = n
.
This is useful to split sizes to combine sized generators.
Complexity O(k log k).
val pos_split : size:int -> int -> int array t
pos_split ~size:k n
generates k
-sized arrays n1,n2,..nk
of strictly positive (non-zero) natural numbers with n1 + n2 + ... + nk = n
.
This is useful to split sizes to combine sized generators.
Complexity O(k log k).
Delay execution of some code until the generator is actually called. This can be used to manually implement recursion or control flow in a generator.
val generate : ?rand:Random.State.t -> n:int -> 'a t -> 'a list
generate ~n g
generates n
instances of g
.
val generate1 : ?rand:Random.State.t -> 'a t -> 'a
generate1 g
generates one instance of g
.