Test capacity of ZST vector

Initially, #50233 accidentally changed the capacity of empty ZST. This
was pointed out during code review. This commit adds a test to prevent
capacity of ZST vectors from accidentally changing to prevent that
from happening again.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/liballoc/tests/vec.rs b/src/liballoc/tests/vec.rs
index e329b45a617..509195cd047 100644
--- a/src/liballoc/tests/vec.rs
+++ b/src/liballoc/tests/vec.rs
@@ -80,6 +80,11 @@ fn test_reserve() {
 }
 
 #[test]
+fn test_zst_capacity() {
+    assert_eq!(Vec::<()>::new().capacity(), usize::max_value());
+}
+
+#[test]
 fn test_extend() {
     let mut v = Vec::new();
     let mut w = Vec::new();