@Test
public void shouldAllowHasNextToBeCalledMultipleTimesWithoutProgressingTheIterator() {
// Given
Iterable<String> iterable = iterableWith("one", "two", "three", "four", "five");
Predicate<String> predicate =
new Predicate<String>() {
public boolean evaluate(String item) {
return item.contains("o");
}
};
// When
FilteredIterator<String> iterator =
new FilteredIterator<String>(iterable.iterator(), predicate);
// Then
assertThat(iterator.hasNext(), is(true));
assertThat(iterator.hasNext(), is(true));
assertThat(iterator.next(), is("one"));
assertThat(iterator.hasNext(), is(true));
assertThat(iterator.next(), is("two"));
assertThat(iterator.hasNext(), is(true));
assertThat(iterator.hasNext(), is(true));
assertThat(iterator.hasNext(), is(true));
assertThat(iterator.next(), is("four"));
assertThat(iterator.hasNext(), is(false));
assertThat(iterator.hasNext(), is(false));
}
@Test
public void shouldNotRemoveAnElementThatDoesNotMatchTheSuppliedPredicate() throws Exception {
// Given
Collection<String> initialElements = collectionWith("one", "three");
Collection<String> expectedElements = collectionWith("three");
// When
FilteredIterator<String> filteredIterator =
new FilteredIterator<String>(
initialElements.iterator(),
new Predicate<String>() {
public boolean evaluate(String item) {
return item.contains("o");
}
});
// Then
assertThat(filteredIterator.next(), is("one"));
filteredIterator.remove();
assertThat(filteredIterator.hasNext(), is(false));
try {
filteredIterator.remove();
fail("Expected an IllegalStateException");
} catch (IllegalStateException exception) {
// continue
}
assertThat(initialElements, is(expectedElements));
}
@Test
public void shouldAllowNullValuesInTheIterator() throws Exception {
// Given
Iterator<Integer> delegateIterator = iterableWith(1, null, 10, 5).iterator();
// When
FilteredIterator<Integer> iterator =
new FilteredIterator<Integer>(
delegateIterator,
new Predicate<Integer>() {
public boolean evaluate(Integer item) {
return item == null || item % 10 != 0;
}
});
// Then
assertThat(iterator.hasNext(), is(true));
assertThat(iterator.next(), is(1));
assertThat(iterator.hasNext(), is(true));
assertThat(iterator.next(), is(nullValue()));
assertThat(iterator.hasNext(), is(true));
assertThat(iterator.next(), is(5));
assertThat(iterator.hasNext(), is(false));
}
@Test(expected = IllegalStateException.class)
public void shouldThrowAnIllegalStateExceptionIfNextHasNotBeenCalledBeforeRemove()
throws Exception {
// Given
Iterator<String> iterator = iterableWith("one", "two", "three").iterator();
// When
FilteredIterator<String> filteredIterator =
new FilteredIterator<String>(
iterator,
new Predicate<String>() {
public boolean evaluate(String item) {
return item.contains("o");
}
});
filteredIterator.hasNext();
filteredIterator.remove();
// Then an IllegalStateException should be thrown
}