Rollup merge of rust-lang#76273 - CraftSpider:master, r=matklad

Move some Vec UI tests into alloc unit tests

A bit of work towards rust-lang#76268, makes a number of the Vec UI tests that are simply running code into unit tests. Ensured that they are being run when testing liballoc locally.

Author: matklad

library/alloc/tests/vec.rs

@@ -74,6 +74,42 @@ fn test_zst_capacity() {
     assert_eq!(Vec::<()>::new().capacity(), usize::MAX);
 }
 
+#[test]
+fn test_indexing() {
+    let v: Vec<isize> = vec![10, 20];
+    assert_eq!(v[0], 10);
+    assert_eq!(v[1], 20);
+    let mut x: usize = 0;
+    assert_eq!(v[x], 10);
+    assert_eq!(v[x + 1], 20);
+    x = x + 1;
+    assert_eq!(v[x], 20);
+    assert_eq!(v[x - 1], 10);
+}
+
+#[test]
+fn test_debug_fmt() {
+    let vec1: Vec<isize> = vec![];
+    assert_eq!("[]", format!("{:?}", vec1));
+
+    let vec2 = vec![0, 1];
+    assert_eq!("[0, 1]", format!("{:?}", vec2));
+
+    let slice: &[isize] = &[4, 5];
+    assert_eq!("[4, 5]", format!("{:?}", slice));
+}
+
+#[test]
+fn test_push() {
+    let mut v = vec![];
+    v.push(1);
+    assert_eq!(v, [1]);
+    v.push(2);
+    assert_eq!(v, [1, 2]);
+    v.push(3);
+    assert_eq!(v, [1, 2, 3]);
+}
+
 #[test]
 fn test_extend() {
     let mut v = Vec::new();
@@ -119,6 +155,18 @@ fn test_extend() {
     assert_eq!(count_x, 1);
 }
 
+#[test]
+fn test_extend_from_slice() {
+    let a: Vec<isize> = vec![1, 2, 3, 4, 5];
+    let b: Vec<isize> = vec![6, 7, 8, 9, 0];
+
+    let mut v: Vec<isize> = a;
+
+    v.extend_from_slice(&b);
+
+    assert_eq!(v, [1, 2, 3, 4, 5, 6, 7, 8, 9, 0]);
+}
+
 #[test]
 fn test_extend_ref() {
     let mut v = vec![1, 2];
@@ -134,6 +182,14 @@ fn test_extend_ref() {
     assert_eq!(v, [1, 2, 3, 4, 5, 6, 7]);
 }
 
+#[test]
+fn test_slice_from_ref() {
+    let values = vec![1, 2, 3, 4, 5];
+    let slice = &values[1..3];
+
+    assert_eq!(slice, [2, 3]);
+}
+
 #[test]
 fn test_slice_from_mut() {
     let mut values = vec![1, 2, 3, 4, 5];