@GwtCompatible public abstract class IteratorTester<E> extends AbstractIteratorTester<E,java.util.Iterator<E>>
Iterator.next()
, Iterator.hasNext()
and Iterator.remove()
operations. This utility takes the brute-force approach of trying all
possible sequences of these operations, up to a given number of steps. So, if
the caller specifies to use n steps, a total of 3^n tests are
actually performed.
For instance, if steps is 5, one example sequence that will be tested is:
This particular order of operations may be unrealistic, and testing all 3^5 of them may be thought of as overkill; however, it's difficult to determine which proper subset of this massive set would be sufficient to expose any possible bug. Brute force is simpler.
To use this class the concrete subclass must implement the
AbstractIteratorTester.newTargetIterator()
method. This is because it's
impossible to test an Iterator without changing its state, so the tester
needs a steady supply of fresh Iterators.
If your iterator supports modification through remove()
, you may
wish to override the verify() method, which is called after
each sequence and is guaranteed to be called using the latest values
obtained from AbstractIteratorTester.newTargetIterator()
.
AbstractIteratorTester.KnownOrder, AbstractIteratorTester.MultiExceptionListIterator, AbstractIteratorTester.Stimulus<E,T extends java.util.Iterator<E>>
add, hasNext, hasPrevious, next, nextIndex, previous, previousIndex, remove, set
Modifier | Constructor and Description |
---|---|
protected |
IteratorTester(int steps,
java.lang.Iterable<? extends IteratorFeature> features,
java.lang.Iterable<E> expectedElements,
AbstractIteratorTester.KnownOrder knownOrder)
Creates an IteratorTester.
|
Modifier and Type | Method and Description |
---|---|
protected java.lang.Iterable<AbstractIteratorTester.Stimulus<E,java.util.Iterator<E>>> |
getStimulusValues()
I'd like to make this a parameter to the constructor, but I can't because
the stimulus instances refer to
this . |
iteratorStimuli, listIteratorStimuli, newTargetIterator, test, verify
protected IteratorTester(int steps, java.lang.Iterable<? extends IteratorFeature> features, java.lang.Iterable<E> expectedElements, AbstractIteratorTester.KnownOrder knownOrder)
steps
- how many operations to test for each tested pair of iteratorsfeatures
- the features supported by the iteratorprotected final java.lang.Iterable<AbstractIteratorTester.Stimulus<E,java.util.Iterator<E>>> getStimulusValues()
AbstractIteratorTester
this
.getStimulusValues
in class AbstractIteratorTester<E,java.util.Iterator<E>>