Evaluates the passed code block if the passed boolean condition is true, else throws UnmetConditionException.
Evaluates the passed code block if the passed boolean condition is true, else throws UnmetConditionException.
The whenever method can be used inside property check functions to skip invocations of the function with
data for which it is known the property would fail. For example, given the following Fraction class:
class Fraction(n: Int, d: Int) { require(d != 0)
require(d != Integer.MIN_VALUE)
require(n != Integer.MIN_VALUE)
val numer = if (d < 0) -1 * n else n
val denom = d.abs
override def toString = numer + " / " + denom
}
import org.scalatest.prop.TableDrivenPropertyChecks._val fractions = Table( ("n", "d"), ( 1, 2), ( -1, 2), ( 1, -2), ( -1, -2), ( 3, 1), ( -3, 1), ( -3, 0), ( 3, -1), ( 3, Integer.MIN_VALUE), (Integer.MIN_VALUE, 3), ( -3, -1) )
Imagine you wanted to check a property against this class with data that includes some
value that are rejected by the constructor, such as a denominator of zero, which should
result in an IllegalArgumentException. You could use whenever
to skip any rows in the fraction that represent illegal arguments, like this:
import org.scalatest.matchers.ShouldMatchers._forAll (fractions) { (n: Int, d: Int) =>
whenever (d != 0 && d != Integer.MIN_VALUE && n != Integer.MIN_VALUE) {
val f = new Fraction(n, d)
if (n < 0 && d < 0 || n > 0 && d > 0) f.numer should be > 0 else if (n != 0) f.numer should be < 0 else f.numer should be === 0
f.denom should be > 0 } }
In this example, rows 6, 8, and 9 have values that would cause a false to be passed
to whenever. (For example, in row 6, d is 0, which means d != 0
will be false.) For those rows, whenever will throw UnmetConditionException,
which will cause the forAll method to skip that row.
the boolean condition that determines whether whenever will evaluate the
fun function (condition is true) or throws UnmetConditionException (<code>condition<code> is false)
funthe function to evaluate if the specified condition is true
Inherited from AnyRef
Inherited from Any