pub fn assert_iterator(it: impl ExactSizeIterator + Clone, expected: &[T]) where T: Copy + core::fmt::Debug + PartialEq, { // Assert that the cloned iterator is correct. assert_exact_size_iterator(it.clone(), expected); // Assert that the original iterator is correct. assert_exact_size_iterator(it, expected); } /// Asserts that `it` adheres to the `ExactSizeIterator` contract. fn assert_exact_size_iterator(mut it: impl ExactSizeIterator, expected: &[T]) where T: Copy + core::fmt::Debug + PartialEq, { assert_eq!(it.len(), expected.len()); assert_eq!(it.size_hint(), expected.iter().size_hint()); for i in 0..expected.len() { let len = it.len(); assert_eq!(len, expected.len() - i); assert_eq!(it.size_hint(), (len, Some(len))); assert_eq!(it.next(), Some(expected[i])); } assert_eq!(it.len(), 0); assert_eq!(it.size_hint(), (0, Some(0))); assert_eq!(it.next(), None); }