view: tests of the 0d extent (#738)

Summary:
tests for the expected properties of `Extent` in the 0d case.

Pull Request resolved: #738

Reviewed By: mariusae

Differential Revision: D79496690

Pulled By: shayne-fletcher

fbshipit-source-id: 6c8d7bcd36c86371e8b6eb36a285f49a1e953423

Author: shayne-fletcher

ndslice/src/view.rs

@@ -792,6 +792,16 @@ mod test {
         assert_eq!(format!("{}", empty_extent), "");
     }
 
+    #[test]
+    fn test_extent_0d() {
+        let e = Extent::new(vec![], vec![]).unwrap();
+        assert_eq!(e.len(), 1);
+        let points: Vec<_> = e.iter().collect();
+        assert_eq!(points.len(), 1);
+        assert_eq!(points[0].coords(), &[]);
+        assert_eq!(points[0].rank(), 0);
+    }
+
     #[test]
     fn test_point_display() {
         let extent = Extent::new(vec!["x".into(), "y".into(), "z".into()], vec![4, 5, 6]).unwrap();