Auto merge of #30956 - KiChjang:move-tests-to-libcollectionstest, r=bluss

Encountered while I was trying to work on #28518. Please let me know whether this is a correct move.

src/libcollections/vec_deque.rs

@@ -2364,34 +2364,4 @@ mod tests {
             }
         }
     }
-
-    #[test]
-    fn test_zst_push() {
-        const N: usize = 8;
-
-        // Zero sized type
-        struct Zst;
-
-        // Test that for all possible sequences of push_front / push_back,
-        // we end up with a deque of the correct size
-
-        for len in 0..N {
-            let mut tester = VecDeque::with_capacity(len);
-            assert_eq!(tester.len(), 0);
-            assert!(tester.capacity() >= len);
-            for case in 0..(1 << len) {
-                assert_eq!(tester.len(), 0);
-                for bit in 0..len {
-                    if case & (1 << bit) != 0 {
-                        tester.push_front(Zst);
-                    } else {
-                        tester.push_back(Zst);
-                    }
-                }
-                assert_eq!(tester.len(), len);
-                assert_eq!(tester.iter().count(), len);
-                tester.clear();
-            }
-        }
-    }
 }

src/test/run-pass/zero-sized-vec-deque-push.rs

@@ -0,0 +1,41 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::collections::VecDeque;
+use std::iter::Iterator;
+
+fn main() {
+    const N: usize = 8;
+
+    // Zero sized type
+    struct Zst;
+
+    // Test that for all possible sequences of push_front / push_back,
+    // we end up with a deque of the correct size
+
+    for len in 0..N {
+        let mut tester = VecDeque::with_capacity(len);
+        assert_eq!(tester.len(), 0);
+        assert!(tester.capacity() >= len);
+        for case in 0..(1 << len) {
+            assert_eq!(tester.len(), 0);
+            for bit in 0..len {
+                if case & (1 << bit) != 0 {
+                    tester.push_front(Zst);
+                } else {
+                    tester.push_back(Zst);
+                }
+            }
+            assert_eq!(tester.len(), len);
+            assert_eq!(tester.iter().count(), len);
+            tester.clear();
+        }
+    }
+}