FIX: in remove_axis(axis, index) specify we need index < len_of(axis)

Removing the index-past-the end does not make sense (it's an ok split index, so the previous code passed through without action).
rust-ndarray · bluss · Apr 9, 2021 · Apr 4, 2021 · Apr 4, 2021 · Apr 5, 2021
commit 107f51f2cee9de50b086bef521896df624d0d2a8
diff --git a/src/impl_methods.rs b/src/impl_methods.rs
@@ -2446,13 +2446,21 @@ where
 
     /// Remove the `index`th elements along `axis` and shift down elements from higher indexes.
     ///
+    /// Note that this "removes" the elements by swapping them around to the end of the axis and
+    /// shortening the length of the axis; the elements are not deinitialized or dropped by this,
+    /// just moved out of view (this only matters for elements with ownership semantics). It's
+    /// similar to slicing an owned array in place.
+    ///
     /// Decreases the length of `axis` by one.
     ///
-    /// ***Panics** if `axis` or `index` is out of bounds.
+    /// ***Panics*** if `axis` is out of bounds<br>
+    /// ***Panics*** if not `index < self.len_of(axis)`.
     pub fn remove_index(&mut self, axis: Axis, index: usize)
     where
         S: DataOwned + DataMut,
     {
+        assert!(index < self.len_of(axis), "index {} must be less than length of Axis({})",
+                index, axis.index());
         let (_, mut tail) = self.view_mut().split_at(axis, index);
         // shift elements to the front
         // use swapping to keep all elements initialized (as required by owned storage)

diff --git a/tests/array.rs b/tests/array.rs
@@ -2439,3 +2439,37 @@ fn test_remove_index() {
                [],
                []]);
 }
+
+#[should_panic(expected="must be less")]
+#[test]
+fn test_remove_index_oob1() {
+    let mut a = arr2(&[[1, 2, 3],
+                       [4, 5, 6],
+                       [7, 8, 9],
+                       [10,11,12]]);
+    a.remove_index(Axis(0), 4);
+}
+
+#[should_panic(expected="must be less")]
+#[test]
+fn test_remove_index_oob2() {
+    let mut a = array![[10], [4], [1]];
+    a.remove_index(Axis(1), 0);
+    assert_eq!(a.shape(), &[3, 0]);
+    assert_eq!(a,
+        array![[],
+               [],
+               []]);
+    a.remove_index(Axis(0), 1); // ok
+    assert_eq!(a,
+        array![[],
+               []]);
+    a.remove_index(Axis(1), 0); // oob
+}
+
+#[should_panic(expected="index out of bounds")]
+#[test]
+fn test_remove_index_oob3() {
+    let mut a = array![[10], [4], [1]];
+    a.remove_index(Axis(2), 0);
+}