PropertyChecks

Performs a configured property checks by applying property check functions passed to its apply methods to arguments supplied by implicitly passed generators, modifying the values in the PropertyGenConfig object passed implicitly to its apply methods with parameter values passed to its constructor.

Instances of this class are returned by trait GeneratorDrivenPropertyChecks forAll method that accepts a variable length argument list of PropertyCheckConfigParam objects. Thus it is used with functions of all six arities. Here are some examples:

forAll (minSize(1), sizeRange(9)) { (a: String) =>
 a.length should equal ((a).length)
}

forAll (minSize(1), sizeRange(9)) { (a: String, b: String) =>
 a.length + b.length should equal ((a + b).length)
}

forAll (minSize(1), sizeRange(9)) { (a: String, b: String, c: String) =>
 a.length + b.length + c.length should equal ((a + b + c).length)
}

forAll (minSize(1), sizeRange(9)) { (a: String, b: String, c: String, d: String) =>
 a.length + b.length + c.length + d.length should equal ((a + b + c + d).length)
}

forAll (minSize(1), sizeRange(9)) { (a: String, b: String, c: String, d: String, e: String) =>
 a.length + b.length + c.length + d.length + e.length should equal ((a + b + c + d + e).length)
}

forAll (minSize(1), sizeRange(9)) { (a: String, b: String, c: String, d: String, e: String, f: String) =>
 a.length + b.length + c.length + d.length + e.length + f.length should equal ((a + b + c + d + e + f).length)
}

In the first example above, the ConfiguredPropertyCheck object is returned by:

forAll (minSize(1), sizeRange(9))

The code that follows is an invocation of one of the ConfiguredPropertyCheck apply methods:

{ (a: String) =>
 a.length should equal ((a).length)
}

A PropertyCheckConfigParam that specifies how many generated values may be discarded, as a multiple of the successful attempts, before the property check is considered to be org.scalatest.prop.PropertyCheckResult.Exhausted.

In GeneratorDrivenPropertyChecks, a property evaluation is discarded if it throws DiscardedEvaluationException, which is produced by a whenever clause that evaluates to false. For example, consider this ScalaTest property check:

// forAll defined in GeneratorDrivenPropertyChecks
forAll { (n: Int) =>
 whenever (n > 0) {
   doubleIt(n) should equal (n * 2)
 }
}

In the above code, whenever a non-positive 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 in Checkers
forAll { (n: Int) =>
 (n > 0) ==> doubleIt(n) == (n * 2)
}

For either kind of property check, MaxDiscardedFactor indicates the maximum fraction of total tests that may be discarded, relative to the number of successful tests. For example, if this is set to 4.0, and you are running 100 tests, it may discard up to 400 tries before considering the test to be org.scalatest.prop.PropertyCheckResult.Exhausted.

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 number of successful property evaluations required for the property to pass.

Once this many evaluations have passed, the property will return PropertyCheckResult.Success.

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).

Describes the configuration to use when evaluating a property.

Internal utility functions for configuration management.

A PropertyCheckConfigParam that (with minSize) 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 size range is added to minSize in order to calculate the maximum size passed to ScalaCheck. Using a range allows compile-time checking of a non-negative number being specified.

Object containing one apply factory method for each TableFor<n> class.

For example, you could create a table of 5 rows and 2 colums like this:

import org.scalatest.prop.Tables._

val examples =
 Table(
   ("a", "b"),
   (  1,   2),
   (  2,   4),
   (  4,   8),
   (  8,  16),
   ( 16,  32)
 )

Because you supplied 2 members in each tuple, the type you'll get back will be a TableFor2. If you wanted a table with just one column you could write this:

val moreExamples =
 Table(
   "powerOfTwo",
        1,
        2,
        4,
        8,
        16
 )

Or if you wanted a table with 10 columns and 10 rows, you could do this:

val multiplicationTable =
 Table(
   ("a", "b", "c", "d", "e", "f", "g", "h", "i", "j"),
   (  1,   2,   3,   4,   5,   6,   7,   8,   9,  10),
   (  2,   4,   6,   8,  10,  12,  14,  16,  18,  20),
   (  3,   6,   9,  12,  15,  18,  21,  24,  27,  30),
   (  4,   8,  12,  16,  20,  24,  28,  32,  36,  40),
   (  5,  10,  15,  20,  25,  30,  35,  40,  45,  50),
   (  6,  12,  18,  24,  30,  36,  42,  48,  54,  60),
   (  7,  14,  21,  28,  35,  42,  49,  56,  63,  70),
   (  8,  16,  24,  32,  40,  48,  56,  64,  72,  80),
   (  9,  18,  27,  36,  45,  54,  63,  72,  81,  90),
   ( 10,  20,  30,  40,  50,  60,  70,  80,  90, 100)
 )

The type of multiplicationTable would be TableFor10. You can pass the resulting tables to a forAll method (defined in trait PropertyChecks), to perform a property check with the data in the table. Or, because tables are sequences of tuples, you can treat them as a Seq.

A PropertyCheckConfigParam that specifies the number of worker threads to use when evaluating a property.

Property evaluation runs on a single thread by default, but may run multiple threads if desired. If so, the evaluation will generally run faster. However, be careful not to use this if there is any risk of deadlocks, race conditions, or other hazards of multi-threaded code in evaluating this property or the code under test.

Create a Generator that returns values in the specified range.

This is the general-purpose function that underlies all of the other xxsBetween() functions in CommonGenerators. It works with any type for which there is an Ordering, a Generator, and a Chooser, making it easy to create Generators for ranges within that type.

The range is inclusive: both ''from'' and ''to'' may be produced by this Generator. Moreover, ''from'' and ''to'' are considered to be edge cases, so they usually ''will'' be produced in a typical run.

The value of from must be less than or equal to the value of to. (However "less than or equal" is defined for this type.)

The "edges" -- the edge case values -- for this type will be taken from the implicit Generator. This function then filters out any that aren't within the specified range, and adds the from and to values as edges.

The implicit Chooser is used to pick random values of the type. That should do most of the heavy lifting.

Since this underlies the more-specific xxsBetween() functions, you may use either those or this when appropriate. For example, this:

 intsBetween(1, 100)

and

 between(1, 100)

are functionally identical so long as the types of the parameters are clear to the compiler. Use whichever suits your project's coding style better.

Create a Generator that returns Bytes in the specified range.

The range is inclusive: both ''from'' and ''to'' may be produced by this Generator. Moreover, ''from'' and ''to'' are considered to be edge cases, so they usually ''will'' be produced in a typical run.

The value of from must be less than or equal to the value of to.

Create a Generator that returns Chars in the specified range.

The range is inclusive: both ''from'' and ''to'' may be produced by this Generator. Moreover, ''from'' and ''to'' are considered to be edge cases, so they usually ''will'' be produced in a typical run.

The value of from must be less than or equal to the value of to.

Generate a bunch of values from a Generator, and distribute them into buckets.

This function mainly exists for the purpose of testing your Generator, and making sure that it is actually creating data with the sort of distribution you expect. You provide the Generator, the number of values to create, and a function that "classifies" each value with a String; it returns a Classification that collates all of the results. You can then look at the Classification to see if the proportions match your expectations.

For example, consider this simple classification of small numbers:

val classification: Classification =
 CommonGenerators.classify(10000, CommonGenerators.intsBetween(0, 9))
 {
   case x if (x % 2) == 0 => "even"
   case _ => "odd"
 }

As expected, the results come out evenly:

classification: org.scalatest.prop.Classification =
50% odd
50% even

The options provided in the PartialFunction do not have to be comprehensive; it is legal for some generated values to not match any of the choices. In this case, those values will not be accounted for in the resulting Classification.

Create a Generator that returns Doubles in the specified range.

The range is inclusive: both ''from'' and ''to'' may be produced by this Generator. Moreover, ''from'' and ''to'' are considered to be edge cases, so they usually ''will'' be produced in a typical run.

The value of from must be less than or equal to the value of to.

Given Generators for two types, L and R, this provides one for Either[L, R].

Given a number of Generators, this creates one that invokes each of its constituents with roughly the same frequency.

Consider this example:

 val numbers: Generator[Char] = ... // generates only digits
 val letters: Generator[Char] = ... // generates only letters
 val punct: Generator[Char]   = ... // generates only punctuation

 val chars: Generator[Char] = evenly(numbers, letters, punct)

The chars Generator should produce numbers, letters and punctuation, each about a third of the time.

Keep in mind that the distribution is invoked randomly, so these are rough proportions. As you invoke the Generator more times, you should see results that are closer and closer to an equal distribution, but the random element will generally keep it inexact.

As usual, the resulting Generator will use the Randomizer passed in to Generator.next to choose which of the constituent Generators to invoke. So if you use the same seed to initialize your Randomizer, you should get the same results.

Note that all of the constituent Generators must produce the same type.

Performs a property check by applying the specified property check function to each row of the specified TableFor22 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor21 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor20 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor19 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor18 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor17 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor16 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor15 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor14 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor13 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor12 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor11 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor10 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor9 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor8 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor7 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor6 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor5 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor4 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor3 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor2 and succeeding if at least one element satisfies the property check.

Performs a property check by applying the specified property check function to each row of the specified TableFor1 and succeeding if at least one element satisfies the property check.

Create a Generator that returns FiniteDoubles in the specified range.

The range is inclusive: both ''from'' and ''to'' may be produced by this Generator. Moreover, ''from'' and ''to'' are considered to be edge cases, so they usually ''will'' be produced in a typical run.

The value of from must be less than or equal to the value of to.

Create a Generator that returns FiniteFloats in the specified range.

The range is inclusive: both ''from'' and ''to'' may be produced by this Generator. Moreover, ''from'' and ''to'' are considered to be edge cases, so they usually ''will'' be produced in a typical run.

The value of from must be less than or equal to the value of to.

Create a Generator that returns Floats in the specified range.

The range is inclusive: both ''from'' and ''to'' may be produced by this Generator. Moreover, ''from'' and ''to'' are considered to be edge cases, so they usually ''will'' be produced in a typical run.

The value of from must be less than or equal to the value of to.

Performs a property check by applying the specified property check function to arguments supplied by implicitly passed generators, modifying the values in the implicitly passed PropertyGenConfig object with explicitly passed parameter values.

This method creates a ConfiguredPropertyCheck object that has six overloaded apply methods that take a function. Thus it is used with functions of all six arities. Here are some examples:

forAll (minSize(1), sizeRange(9)) { (a: String) =>
 a.length should equal ((a).length)
}

forAll (minSize(1), sizeRange(9)) { (a: String, b: String) =>
 a.length + b.length should equal ((a + b).length)
}

forAll (minSize(1), sizeRange(9)) { (a: String, b: String, c: String) =>
 a.length + b.length + c.length should equal ((a + b + c).length)
}

forAll (minSize(1), sizeRange(9)) { (a: String, b: String, c: String, d: String) =>
 a.length + b.length + c.length + d.length should equal ((a + b + c + d).length)
}

forAll (minSize(1), sizeRange(9)) { (a: String, b: String, c: String, d: String, e: String) =>
 a.length + b.length + c.length + d.length + e.length should equal ((a + b + c + d + e).length)
}

forAll (minSize(1), sizeRange(9)) { (a: String, b: String, c: String, d: String, e: String, f: String) =>
 a.length + b.length + c.length + d.length + e.length + f.length should equal ((a + b + c + d + e + f).length)
}

Performs a property check by applying the specified property check function to each row of the specified TableFor22.

Performs a property check by applying the specified property check function to each row of the specified TableFor21.

Performs a property check by applying the specified property check function to each row of the specified TableFor20.

Performs a property check by applying the specified property check function to each row of the specified TableFor19.

Performs a property check by applying the specified property check function to each row of the specified TableFor18.

Performs a property check by applying the specified property check function to each row of the specified TableFor17.

Performs a property check by applying the specified property check function to each row of the specified TableFor16.

Performs a property check by applying the specified property check function to each row of the specified TableFor15.

Performs a property check by applying the specified property check function to each row of the specified TableFor14.

Performs a property check by applying the specified property check function to each row of the specified TableFor13.

Performs a property check by applying the specified property check function to each row of the specified TableFor12.

Performs a property check by applying the specified property check function to each row of the specified TableFor11.

Performs a property check by applying the specified property check function to each row of the specified TableFor10.

Performs a property check by applying the specified property check function to each row of the specified TableFor9.

Performs a property check by applying the specified property check function to each row of the specified TableFor8.

Performs a property check by applying the specified property check function to each row of the specified TableFor7.