@Test
public void shouldReturnEmptySeqWhenZipEmptyWithEmpty() throws Exception {
// given
final LazySeq<Integer> empty = empty();
// when
final LazySeq<Integer> zipped = empty.zip(empty, (a, b) -> a + b);
// then
assertThat(zipped).isEmpty();
}
@Test
public void shouldTrimFirstFixedSeqIfLonger() throws Exception {
// given
final LazySeq<String> first = of("A", "B", "C", "D");
final LazySeq<Integer> second = of(1, 2, 3);
// when
final LazySeq<String> zipped = first.zip(second, (a, b) -> a + b);
// then
assertThat(zipped).isEqualTo(of("A1", "B2", "C3"));
}
@Test
public void shouldZipTwoLazyFiniteSequencesOfSameSize() throws Exception {
// given
final LazySeq<String> first = cons("A", () -> cons("B", () -> of("C")));
final LazySeq<Integer> second = cons(1, () -> cons(2, () -> of(3)));
// when
final LazySeq<String> zipped = first.zip(second, (a, b) -> a + b);
// then
assertThat(zipped).isEqualTo(of("A1", "B2", "C3"));
}
@Test
public void shouldZipInfiniteWithFiniteSeq() throws Exception {
// given
final LazySeq<Integer> naturals = numbers(1);
final LazySeq<Integer> primes = primes().take(5);
// when
final LazySeq<String> zipped = naturals.zip(primes, (n, p) -> n + ": " + p);
// then
assertThat(zipped).isEqualTo(of("1: 2", "2: 3", "3: 5", "4: 7", "5: 11"));
}
@Test
public void shouldTrimFirstLazyButFiniteSeqIfLonger() throws Exception {
// given
final LazySeq<String> first = cons("A", () -> cons("B", () -> cons("C", () -> of("D"))));
final LazySeq<Integer> second = cons(1, () -> cons(2, () -> of(3)));
// when
final LazySeq<String> zipped = first.zip(second, (a, b) -> a + b);
// then
assertThat(zipped).isEqualTo(of("A1", "B2", "C3"));
}
@Test
public void shouldNotEvaluateTailWhenZippingTwoSequences() throws Exception {
// given
final LazySeq<String> first = cons("A", firstSupplier);
final LazySeq<Integer> second = cons(1, secondSupplier);
// when
first.zip(second, (a, b) -> a + b);
// then
verifyZeroInteractions(firstSupplier);
verifyZeroInteractions(secondSupplier);
}