Module QCheck.Test

type 'a cell

A single property test

val fail_report : string -> 'a

Fail the test with some additional message that will be reported.

since
0.7
val fail_reportf : ('a, Format.formatter, unit, 'b) Pervasives.format4 -> 'a

Format version of fail_report

since
0.7
val make_cell : ?⁠if_assumptions_fail:([ `Fatal | `Warning ] * float) -> ?⁠count:int -> ?⁠long_factor:int -> ?⁠max_gen:int -> ?⁠max_fail:int -> ?⁠small:('a -> int) -> ?⁠name:string -> 'a arbitrary -> ('a -> bool) -> 'a cell

make_cell arb prop builds a test that checks property prop on instances of the generator arb.

parameter name

the name of the test.

parameter count

number of test cases to run, counting only the test cases which satisfy preconditions.

parameter long_factor

the factor by which to multiply count, max_gen and max_fail when running a long test (default: 1).

parameter max_gen

maximum number of times the generation function is called in total to replace inputs that do not satisfy preconditions (should be >= count).

parameter max_fail

maximum number of failures before we stop generating inputs. This is useful if shrinking takes too much time.

parameter small

kept for compatibility reasons; if provided, replaces the field arbitrary.small. If there is no shrinking function but there is a small function, only the smallest failures will be printed.

parameter if_assumptions_fail

the minimum fraction of tests that must satisfy the precondition for a success to be considered valid. The fraction should be between 0. and 1. A warning will be emitted otherwise if the flag is `Warning, the test will be a failure if the flag is `Fatal. (since 0.10)

val get_arbitrary : 'a cell -> 'a arbitrary
val get_law : 'a cell -> 'a -> bool
val get_name : _ cell -> string
val set_name : _ cell -> string -> unit
val get_count : _ cell -> int

Get the count of a cell.

since
0.5.3
val get_long_factor : _ cell -> int

Get the long factor of a cell.

since
0.5.3
type t =
| Test : 'a cell -> t

Same as 'a cell, but masking the type parameter. This allows to put tests on different types in the same list of tests.

val make : ?⁠if_assumptions_fail:([ `Fatal | `Warning ] * float) -> ?⁠count:int -> ?⁠long_factor:int -> ?⁠max_gen:int -> ?⁠max_fail:int -> ?⁠small:('a -> int) -> ?⁠name:string -> 'a arbitrary -> ('a -> bool) -> t

make arb prop builds a test that checks property prop on instances of the generator arb. See make_cell for a description of the parameters.

Running the test
exception Test_fail of string * string list

Exception raised when a test failed, with the list of counter-examples. Test_fail (name, l) means test name failed on elements of l.

exception Test_error of string * string * exn * string

Exception raised when a test raised an exception e, with the sample that triggered the exception. Test_error (name, i, e, st) means name failed on i with exception e, and st is the stacktrace (if enabled) or an empty string.

val print_instance : 'a arbitrary -> 'a -> string
val print_c_ex : 'a arbitrary -> 'a TestResult.counter_ex -> string
val print_fail : 'a arbitrary -> string -> 'a TestResult.counter_ex list -> string
val print_fail_other : string -> msg:string -> string
val print_error : ?⁠st:string -> 'a arbitrary -> string -> ('a TestResult.counter_ex * exn) -> string
val print_test_fail : string -> string list -> string
val print_test_error : string -> string -> exn -> string -> string
val print_collect : (string, int) Hashtbl.t -> string

Print "collect" results.

since
0.6
val print_stat : ('a stat * (int, int) Hashtbl.t) -> string

Print statistics.

since
0.6
val check_result : 'a cell -> 'a TestResult.t -> unit

check_result cell res checks that res is Ok _, and returns unit. Otherwise, it raises some exception.

raises Test_error

if res = Error _

raises Test_error

if res = Failed _

type res =
| Success
| Failure
| FalseAssumption
| Error of exn * string
type 'a event =
| Generating
| Collecting of 'a
| Testing of 'a
| Shrunk of int * 'a
| Shrinking of int * int * 'a
type 'a handler = string -> 'a cell -> 'a event -> unit

Handler executed after each event during testing of an instance.

type 'a step = string -> 'a cell -> 'a -> res -> unit

Callback executed after each instance of a test has been run. The callback is given the instance tested, and the current results of the test.

type 'a callback = string -> 'a cell -> 'a TestResult.t -> unit

Callback executed after each test has been run. f name cell res means test cell, named name, gave res.

val check_cell : ?⁠long:bool -> ?⁠call:'a callback -> ?⁠step:'a step -> ?⁠handler:'a handler -> ?⁠rand:Random.State.t -> 'a cell -> 'a TestResult.t

check_cell ~long ~rand test generates up to count random values of type 'a using arbitrary and the random state st. The predicate law is called on them and if it returns false or raises an exception then we have a counter-example for the law.

parameter long

if true then multiply the number of instances to generate by the cell's long_factor.

parameter call

function called on each test case, with the result.

parameter step

function called on each instance of the test case, with the result.

returns

the result of the test.

val check_cell_exn : ?⁠long:bool -> ?⁠call:'a callback -> ?⁠step:'a step -> ?⁠rand:Random.State.t -> 'a cell -> unit

Same as check_cell but calls check_result on the result.

raises Test_error

if res = Error _

raises Test_error

if res = Failed _

val check_exn : ?⁠long:bool -> ?⁠rand:Random.State.t -> t -> unit

Checks the property against some test cases, and calls check_result, which might raise an exception in case of failure.

raises Test_error

if res = Error _

raises Test_error

if res = Failed _