Checkers
A PropertyCheckConfigParam that specifies the maximum number of discarded
property evaluations allowed during property evaluation.
A PropertyCheckConfigParam that specifies the maximum number of discarded
property evaluations allowed during property evaluation.
In GeneratorDrivenPropertyChecks, a property evaluation is discarded if it throws
DiscardedEvaluationException, which is produce by whenever clause that
evaluates to false. For example, consider this ScalaTest property check:
// forAll defined inIn the above code, whenever a non-positiveGeneratorDrivenPropertyChecksforAll { (n: Int) => whenever (n > 0) { doubleIt(n) should equal (n * 2) } }
n is passed, the property function will complete abruptly
with DiscardedEvaluationException.
Similarly, in Checkers, a property evaluation is discarded if the expression to the left
of ScalaCheck's ==> operator is false. Here's an example:
// forAll defined inFor either kind of property check,CheckersforAll { (n: Int) => (n > 0) ==> doubleIt(n) == (n * 2) }
MaxDiscarded indicates the maximum number of discarded
evaluations that will be allowed. As soon as one past this number of evaluations indicates it needs to be discarded,
the property check will fail.
if specified value is less than zero.
A PropertyCheckConfigParam that specifies the maximum size parameter to
provide to ScalaCheck, which it will use when generating objects for which size matters (such as
strings or lists).
A PropertyCheckConfigParam that specifies the maximum size parameter to
provide to ScalaCheck, which it will use when generating objects for which size matters (such as
strings or lists).
Note that the maximum size should be greater than or equal to the minimum size. This requirement is
enforced by the PropertyCheckConfig constructor and the forAll methods of
traits PropertyChecks and Checkers. In other words, it is enforced at the point
both a maximum and minimum size are provided together.
if specified value is less than zero.
A PropertyCheckConfigParam that specifies the minimum size parameter to
provide to ScalaCheck, which it will use when generating objects for which size matters (such as
strings or lists).
A PropertyCheckConfigParam that specifies the minimum size parameter to
provide to ScalaCheck, which it will use when generating objects for which size matters (such as
strings or lists).
if specified value is less than zero.
A PropertyCheckConfigParam that specifies the minimum number of successful
property evaluations required for the property to pass.
A PropertyCheckConfigParam that specifies the minimum number of successful
property evaluations required for the property to pass.
if specified value is less than or equal to zero.
Configuration object for property checks.
Configuration object for property checks.
The default values for the parameters are:
| minSuccessful | 100 |
| maxDiscarded | 500 |
| minSize | 0 |
| maxSize | 100 |
| workers | 1 |
the minimum number of successful property evaluations required for the property to pass.
the maximum number of discarded property evaluations allowed during a property check
the minimum size parameter to provide to ScalaCheck, which it will use when generating objects for which size matters (such as strings or lists).
the maximum size parameter to provide to ScalaCheck, which it will use when generating objects for which size matters (such as strings or lists).
specifies the number of worker threads to use during property evaluation
if the specified minSuccessful value is less than or equal to zero,
the specified maxDiscarded value is less than zero,
the specified minSize value is less than zero,
the specified maxSize value is less than zero,
the specified minSize is greater than the specified or default value of maxSize, or
the specified workers value is less than or equal to zero.
Abstract class defining a family of configuration parameters for property checks.
Abstract class defining a family of configuration parameters for property checks.
The subclasses of this abstract class are used to pass configuration information to
the forAll methods of traits PropertyChecks (for ScalaTest-style
property checks) and Checkers(for ScalaCheck-style property checks).
A PropertyCheckConfigParam that specifies the number of worker threads
to use when evaluating a property.
A PropertyCheckConfigParam that specifies the number of worker threads
to use when evaluating a property.
if specified value is less than or equal to zero.
Check a property.
Check a property.
the property to check
if a test case is discovered for which the property doesn't hold.
Check a property with the given testing parameters.
Check a property with the given testing parameters.
the property to check
the test parameters
if a test case is discovered for which the property doesn't hold.
Convert the passed 6-arg function into a property, and check it.
Convert the passed 6-arg function into a property, and check it.
the function to be converted into a property and checked
if a test case is discovered for which the property doesn't hold.
Convert the passed 5-arg function into a property, and check it.
Convert the passed 5-arg function into a property, and check it.
the function to be converted into a property and checked
if a test case is discovered for which the property doesn't hold.
Convert the passed 4-arg function into a property, and check it.
Convert the passed 4-arg function into a property, and check it.
the function to be converted into a property and checked
if a test case is discovered for which the property doesn't hold.
Convert the passed 3-arg function into a property, and check it.
Convert the passed 3-arg function into a property, and check it.
the function to be converted into a property and checked
if a test case is discovered for which the property doesn't hold.
Convert the passed 2-arg function into a property, and check it.
Convert the passed 2-arg function into a property, and check it.
the function to be converted into a property and checked
if a test case is discovered for which the property doesn't hold.
Convert the passed 1-arg function into a property, and check it.
Convert the passed 1-arg function into a property, and check it.
the function to be converted into a property and checked
if a test case is discovered for which the property doesn't hold.
Implicit PropertyCheckConfig value providing default configuration values.
Implicit PropertyCheckConfig value providing default configuration values.
Returns a MaxDiscarded property check configuration parameter containing the passed value, which specifies the maximum number of discarded
property evaluations allowed during property evaluation.
Returns a MaxDiscarded property check configuration parameter containing the passed value, which specifies the maximum number of discarded
property evaluations allowed during property evaluation.
if specified value is less than zero.
Returns a MaxSize property check configuration parameter containing the passed value, which specifies the maximum size parameter to
provide to ScalaCheck, which it will use when generating objects for which size matters (such as
strings or lists).
Returns a MaxSize property check configuration parameter containing the passed value, which specifies the maximum size parameter to
provide to ScalaCheck, which it will use when generating objects for which size matters (such as
strings or lists).
Note that the maximum size should be greater than or equal to the minimum size. This requirement is
enforced by the PropertyCheckConfig constructor and the forAll methods of
traits PropertyChecks and Checkers. In other words, it is enforced at the point
both a maximum and minimum size are provided together.
if specified value is less than zero.
Returns a MinSize property check configuration parameter containing the passed value, which specifies the minimum size parameter to
provide to ScalaCheck, which it will use when generating objects for which size matters (such as
strings or lists).
Returns a MinSize property check configuration parameter containing the passed value, which specifies the minimum size parameter to
provide to ScalaCheck, which it will use when generating objects for which size matters (such as
strings or lists).
if specified value is less than zero.
Returns a MinSuccessful property check configuration parameter containing the passed value, which specifies the minimum number of successful
property evaluations required for the property to pass.
Returns a MinSuccessful property check configuration parameter containing the passed value, which specifies the minimum number of successful
property evaluations required for the property to pass.
if specified value is less than or equal to zero.
Returns a Workers property check configuration parameter containing the passed value, which specifies the number of worker threads
to use when evaluating a property.
Returns a Workers property check configuration parameter containing the passed value, which specifies the number of worker threads
to use when evaluating a property.
if specified value is less than or equal to zero.
Trait that contains several “check” methods that perform ScalaCheck property checks. If ScalaCheck finds a test case for which a property doesn't hold, the problem will be reported as a ScalaTest test failure.
To use ScalaCheck, you specify properties and, in some cases, generators that generate test data. You need not always create generators, because ScalaCheck provides many default generators for you that can be used in many situations. ScalaCheck will use the generators to generate test data and with that data run tests that check that the property holds. Property-based tests can, therefore, give you a lot more testing for a lot less code than assertion-based tests. Here's an example of using ScalaCheck from a
TheJUnitSuite:checkmethod, defined inCheckers, makes it easy to write property-based tests inside ScalaTest, JUnit, and TestNG test suites. This example specifies a property thatList's:::method should obey. ScalaCheck properties are expressed as function values that take the required test data as parameters. ScalaCheck will generate test data using generators and repeatedly pass generated data to the function. In this case, the test data is composed of integer lists namedaandb. Inside the body of the function, you see: The property in this case is aBooleanexpression that will yield true if the size of the concatenated list is equal to the size of each individual list added together. With this small amount of code, ScalaCheck will generate possibly hundreds of value pairs foraandband test each pair, looking for a pair of integers for which the property doesn't hold. If the property holds true for every value ScalaCheck tries,checkreturns normally. Otherwise,checkwill complete abruptly with aTestFailedExceptionthat contains information about the failure, including the values that cause the property to be false. For more information on using ScalaCheck properties, see the documentation for ScalaCheck, which is available from http://code.google.com/p/scalacheck/. To execute a suite that mixes inCheckerswith ScalaTest'sRunner, you must include ScalaCheck's jar file on the class path or runpath. == Property check configuration == The property checks performed by thecheckmethods of this trait can be flexibly configured via the services provided by supertraitConfiguration. The five configuration parameters for property checks along with their default values and meanings are described in the following table:checkmethods of traitCheckerseach take aPropertyCheckConfigobject as an implicit parameter. This object provides values for each of the five configuration parameters. TraitConfigurationprovides an implicitvalnamedgeneratorDrivenConfigwith each configuration parameter set to its default value. If you want to set one or more configuration parameters to a different value for all property checks in a suite you can override this val (or hide it, for example, if you are importing the members of theCheckerscompanion object rather than mixing in the trait.) For example, if you want all parameters at their defaults except forminSizeandmaxSize, you can overridegeneratorDrivenConfig, like this: Or, if hide it by declaring a variable of the same name in whatever scope you want the changed values to be in effect: In addition to taking aPropertyCheckConfigobject as an implicit parameter, thecheckmethods of traitCheckersalso take a variable length argument list ofPropertyCheckConfigParamobjects that you can use to override the values provided by the implicitPropertyCheckConfigfor a singlecheckinvocation. You place these configuration settings after the property or property function, For example, if you want to setminSuccessfulto 500 for just one particularcheckinvocation, you can do so like this: This invocation ofcheckwill use 500 forminSuccessfuland whatever values are specified by the implicitly passedPropertyCheckConfigobject for the other configuration parameters. If you want to set multiple configuration parameters in this way, just list them separated by commas: The previous configuration approach works the same inCheckersas it does inGeneratorDrivenPropertyChecks. TraitCheckersalso provides onecheckmethod that takes anorg.scalacheck.Test.Parametersobject, in case you want to configure ScalaCheck that way. For more information, see the documentation for supertraitConfiguration.