Add tests for get_disjoint_mut

Author: cmrschwarz

tests/slab.rs

@@ -2,7 +2,10 @@
 
 use slab::*;
 
-use std::panic::{catch_unwind, resume_unwind, AssertUnwindSafe};
+use std::{
+    iter::FromIterator,
+    panic::{catch_unwind, resume_unwind, AssertUnwindSafe},
+};
 
 #[test]
 fn insert_get_remove_one() {
@@ -730,3 +733,37 @@ fn clone_from() {
     assert_eq!(iter2.next(), None);
     assert!(slab2.capacity() >= 10);
 }
+
+#[test]
+fn get_disjoint_mut() {
+    let mut slab = Slab::from_iter((0..5).enumerate());
+    slab.remove(1);
+    slab.remove(3);
+
+    assert_eq!(slab.get_disjoint_mut([]), Ok([]));
+
+    assert_eq!(
+        slab.get_disjoint_mut([4, 2, 0]).unwrap().map(|x| *x),
+        [4, 2, 0]
+    );
+
+    assert_eq!(
+        slab.get_disjoint_mut([42, 2, 1, 2]),
+        Err(GetDisjointMutError::OverlappingIndices)
+    );
+
+    assert_eq!(
+        slab.get_disjoint_mut([1, 5]),
+        Err(GetDisjointMutError::IndexVacant)
+    );
+
+    assert_eq!(
+        slab.get_disjoint_mut([5, 1]),
+        Err(GetDisjointMutError::IndexOutOfBounds)
+    );
+
+    let [a, b] = slab.get_disjoint_mut([0, 4]).unwrap();
+    (*a, *b) = (*b, *a);
+    assert_eq!(slab[0], 4);
+    assert_eq!(slab[4], 0);
+}