+
+ #[test]
+ fn test_rotate_through_iterators() {
+ // two nested vectors
+ let a = vec![vec!["a0", "b0", "c0"].into_iter(), vec!["a1", "b1"].into_iter()];
+ let result = rotate_through_iterators(a).collect::<Vec<_>>();
+
+ let expected = vec!["a0", "a1", "b0", "b1", "c0"];
+ assert_eq!(expected, result);
+
+ // test single nested vector
+ let a = vec![vec!["a0", "b0", "c0"].into_iter()];
+ let result = rotate_through_iterators(a).collect::<Vec<_>>();
+
+ let expected = vec!["a0", "b0", "c0"];
+ assert_eq!(expected, result);
+
+ // test second vector with only one element
+ let a = vec![vec!["a0", "b0", "c0"].into_iter(), vec!["a1"].into_iter()];
+ let result = rotate_through_iterators(a).collect::<Vec<_>>();
+
+ let expected = vec!["a0", "a1", "b0", "c0"];
+ assert_eq!(expected, result);
+
+ // test three nestend vectors
+ let a = vec![vec!["a0"].into_iter(), vec!["a1", "b1", "c1"].into_iter(), vec!["a2"].into_iter()];
+ let result = rotate_through_iterators(a).collect::<Vec<_>>();
+
+ let expected = vec!["a0", "a1", "a2", "b1", "c1"];
+ assert_eq!(expected, result);
+
+ // test single nested vector with a single value
+ let a = vec![vec!["a0"].into_iter()];
+ let result = rotate_through_iterators(a).collect::<Vec<_>>();
+
+ let expected = vec!["a0"];
+ assert_eq!(expected, result);
+
+ // test single empty nested vector
+ let a:Vec<std::vec::IntoIter<&str>> = vec![vec![].into_iter()];
+ let result = rotate_through_iterators(a).collect::<Vec<&str>>();
+ let expected:Vec<&str> = vec![];
+
+ assert_eq!(expected, result);
+
+ // test first nested vector is empty
+ let a:Vec<std::vec::IntoIter<&str>>= vec![vec![].into_iter(), vec!["a1", "b1", "c1"].into_iter()];
+ let result = rotate_through_iterators(a).collect::<Vec<&str>>();
+
+ let expected = vec!["a1", "b1", "c1"];
+ assert_eq!(expected, result);
+
+ // test two empty vectors
+ let a:Vec<std::vec::IntoIter<&str>> = vec![vec![].into_iter(), vec![].into_iter()];
+ let result = rotate_through_iterators(a).collect::<Vec<&str>>();
+
+ let expected:Vec<&str> = vec![];
+ assert_eq!(expected, result);
+
+ // test an empty vector amongst other filled vectors
+ let a = vec![
+ vec!["a0", "b0", "c0"].into_iter(),
+ vec![].into_iter(),
+ vec!["a1", "b1", "c1"].into_iter(),
+ vec!["a2", "b2", "c2"].into_iter(),
+ ];
+ let result = rotate_through_iterators(a).collect::<Vec<_>>();
+
+ let expected = vec!["a0", "a1", "a2", "b0", "b1", "b2", "c0", "c1", "c2"];
+ assert_eq!(expected, result);
+
+ // test a filled vector between two empty vectors
+ let a = vec![vec![].into_iter(), vec!["a1", "b1", "c1"].into_iter(), vec![].into_iter()];
+ let result = rotate_through_iterators(a).collect::<Vec<_>>();
+
+ let expected = vec!["a1", "b1", "c1"];
+ assert_eq!(expected, result);
+
+ // test an empty vector at the end of the vectors
+ let a = vec![vec!["a0", "b0", "c0"].into_iter(), vec![].into_iter()];
+ let result = rotate_through_iterators(a).collect::<Vec<_>>();
+
+ let expected = vec!["a0", "b0", "c0"];
+ assert_eq!(expected, result);
+
+ // test multiple empty vectors amongst multiple filled vectors
+ let a = vec![
+ vec![].into_iter(),
+ vec!["a1", "b1", "c1"].into_iter(),
+ vec![].into_iter(),
+ vec!["a3", "b3"].into_iter(),
+ vec![].into_iter(),
+ ];
+
+ let result = rotate_through_iterators(a).collect::<Vec<_>>();
+
+ let expected = vec!["a1", "a3", "b1", "b3", "c1"];
+ assert_eq!(expected, result);
+
+ // test one element in the first nested vectore and two elements in the second nested
+ // vector
+ let a = vec![vec!["a0"].into_iter(), vec!["a1", "b1"].into_iter()];
+ let result = rotate_through_iterators(a).collect::<Vec<_>>();
+
+ let expected = vec!["a0", "a1", "b1"];
+ assert_eq!(expected, result);
+ }