add unit test for balltree

src/ball_tree.rs

@@ -577,6 +577,23 @@ mod test {
         tree.query_nearest(&point);
     }
 
+    #[test]
+    #[should_panic]
+    fn ball_tree_column_base() {
+        let array = array![[1., 1.], [1., 1.1], [9., 9.]];
+        let fortran = array.reversed_axes();
+        let _ = BallTree::euclidean(fortran).expect("`array` should not be empty");
+    }
+
+    #[test]
+    fn ball_tree_metric() {
+        let array = array![[1., 1.], [1., 1.1], [9., 9.]];
+        let tree = BallTree::new(array.clone(), Euclidean::default())
+            .expect("`array` should not be empty");
+        let tree1 = BallTree::euclidean(array).expect("`array` should not be empty");
+        assert_eq!(tree.metric, tree1.metric);
+    }
+
     #[test]
     fn ball_tree_3() {
         let array = array![[1., 1.], [1., 1.1], [9., 9.]];
@@ -598,6 +615,12 @@ mod test {
         neighbors.sort_unstable();
         assert_eq!(neighbors, &[0, 1]);
 
+        let neighbors = tree.nearest_neighbor_in_subtree(&aview1(&[20., 20.]), 0, 1.);
+        assert_eq!(neighbors, None);
+
+        let neighbors = tree.query_radius(&aview1(&[20., 20.]), 1.);
+        assert_eq!(neighbors, &[]);
+
         let point = aview1(&[1.1, 1.2]);
         let neighbor = tree.query_nearest(&point);
         assert_eq!(neighbor.0, 1);
@@ -658,6 +681,10 @@ mod test {
         let point = aview1(&[1., 2.]);
         let neighbor = tree.query_nearest(&point);
         assert!(approx::abs_diff_eq!(neighbor.1, 1_f64.sqrt()));
+
+        let point = aview1(&[1., 1.]);
+        let neighbor = tree.query_nearest(&point);
+        assert!(approx::abs_diff_eq!(neighbor.1, 0_f64.sqrt()));
     }
 
     #[test]

src/distance.rs

@@ -9,7 +9,7 @@ pub trait Metric<A> {
     fn distance(&self, _: &ArrayView1<A>, _: &ArrayView1<A>) -> A;
 }
 
-#[derive(Default, Clone)]
+#[derive(Default, Clone, Debug, PartialEq)]
 pub struct Euclidean {}
 
 unsafe impl Sync for Euclidean {}