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-rw-r--r--library/alloc/src/alloc.rs18
-rw-r--r--library/alloc/src/borrow.rs6
-rw-r--r--library/alloc/src/bstr.rs20
-rw-r--r--library/alloc/src/collections/binary_heap/mod.rs5
-rw-r--r--library/alloc/src/collections/mod.rs24
-rw-r--r--library/alloc/src/collections/vec_deque/mod.rs1
-rw-r--r--library/alloc/src/collections/vec_deque/spec_extend.rs2
-rw-r--r--library/alloc/src/collections/vec_deque/spec_from_iter.rs1
-rw-r--r--library/alloc/src/ffi/c_str.rs16
-rw-r--r--library/alloc/src/lib.rs39
-rw-r--r--library/alloc/src/macros.rs23
-rw-r--r--library/alloc/src/raw_vec/mod.rs (renamed from library/alloc/src/raw_vec.rs)4
-rw-r--r--library/alloc/src/rc.rs10
-rw-r--r--library/alloc/src/rc/tests.rs664
-rw-r--r--library/alloc/src/slice.rs182
-rw-r--r--library/alloc/src/str.rs3
-rw-r--r--library/alloc/src/string.rs30
-rw-r--r--library/alloc/src/sync.rs4
-rw-r--r--library/alloc/src/testing/crash_test.rs120
-rw-r--r--library/alloc/src/testing/mod.rs3
-rw-r--r--library/alloc/src/testing/ord_chaos.rs81
-rw-r--r--library/alloc/src/testing/rng.rs28
-rw-r--r--library/alloc/src/vec/into_iter.rs5
-rw-r--r--library/alloc/src/vec/mod.rs47
24 files changed, 138 insertions, 1198 deletions
diff --git a/library/alloc/src/alloc.rs b/library/alloc/src/alloc.rs
index 3bfdc68dcda..2f752f6eb39 100644
--- a/library/alloc/src/alloc.rs
+++ b/library/alloc/src/alloc.rs
@@ -5,9 +5,7 @@
 #[stable(feature = "alloc_module", since = "1.28.0")]
 #[doc(inline)]
 pub use core::alloc::*;
-#[cfg(not(test))]
 use core::hint;
-#[cfg(not(test))]
 use core::ptr::{self, NonNull};
 
 unsafe extern "Rust" {
@@ -44,14 +42,10 @@ unsafe extern "Rust" {
 /// accessed through the [free functions in `alloc`](self#functions).
 #[unstable(feature = "allocator_api", issue = "32838")]
 #[derive(Copy, Clone, Default, Debug)]
-#[cfg(not(test))]
 // the compiler needs to know when a Box uses the global allocator vs a custom one
 #[lang = "global_alloc_ty"]
 pub struct Global;
 
-#[cfg(test)]
-pub use std::alloc::Global;
-
 /// Allocates memory with the global allocator.
 ///
 /// This function forwards calls to the [`GlobalAlloc::alloc`] method
@@ -180,7 +174,6 @@ pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 {
     }
 }
 
-#[cfg(not(test))]
 impl Global {
     #[inline]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
@@ -246,7 +239,6 @@ impl Global {
 }
 
 #[unstable(feature = "allocator_api", issue = "32838")]
-#[cfg(not(test))]
 unsafe impl Allocator for Global {
     #[inline]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
@@ -346,7 +338,7 @@ unsafe impl Allocator for Global {
 }
 
 /// The allocator for `Box`.
-#[cfg(all(not(no_global_oom_handling), not(test)))]
+#[cfg(not(no_global_oom_handling))]
 #[lang = "exchange_malloc"]
 #[inline]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
@@ -395,7 +387,7 @@ unsafe extern "Rust" {
 /// [no_std]: https://doc.rust-lang.org/reference/names/preludes.html#the-no_std-attribute
 #[stable(feature = "global_alloc", since = "1.28.0")]
 #[rustc_const_unstable(feature = "const_alloc_error", issue = "92523")]
-#[cfg(all(not(no_global_oom_handling), not(test)))]
+#[cfg(not(no_global_oom_handling))]
 #[cold]
 #[optimize(size)]
 pub const fn handle_alloc_error(layout: Layout) -> ! {
@@ -419,11 +411,7 @@ pub const fn handle_alloc_error(layout: Layout) -> ! {
     ct_error(layout)
 }
 
-// For alloc test `std::alloc::handle_alloc_error` can be used directly.
-#[cfg(all(not(no_global_oom_handling), test))]
-pub use std::alloc::handle_alloc_error;
-
-#[cfg(all(not(no_global_oom_handling), not(test)))]
+#[cfg(not(no_global_oom_handling))]
 #[doc(hidden)]
 #[allow(unused_attributes)]
 #[unstable(feature = "alloc_internals", issue = "none")]
diff --git a/library/alloc/src/borrow.rs b/library/alloc/src/borrow.rs
index 17dad3277b9..07f51b7614f 100644
--- a/library/alloc/src/borrow.rs
+++ b/library/alloc/src/borrow.rs
@@ -32,7 +32,7 @@ where
 /// implementing the `Clone` trait. But `Clone` works only for going from `&T`
 /// to `T`. The `ToOwned` trait generalizes `Clone` to construct owned data
 /// from any borrow of a given type.
-#[cfg_attr(not(test), rustc_diagnostic_item = "ToOwned")]
+#[rustc_diagnostic_item = "ToOwned"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait ToOwned {
     /// The resulting type after obtaining ownership.
@@ -54,7 +54,7 @@ pub trait ToOwned {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use = "cloning is often expensive and is not expected to have side effects"]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "to_owned_method")]
+    #[rustc_diagnostic_item = "to_owned_method"]
     fn to_owned(&self) -> Self::Owned;
 
     /// Uses borrowed data to replace owned data, usually by cloning.
@@ -175,7 +175,7 @@ where
 /// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "Cow")]
+#[rustc_diagnostic_item = "Cow"]
 pub enum Cow<'a, B: ?Sized + 'a>
 where
     B: ToOwned,
diff --git a/library/alloc/src/bstr.rs b/library/alloc/src/bstr.rs
index 61e61019b50..338c7ac7f88 100644
--- a/library/alloc/src/bstr.rs
+++ b/library/alloc/src/bstr.rs
@@ -12,13 +12,10 @@ use core::ops::{
     Deref, DerefMut, DerefPure, Index, IndexMut, Range, RangeFrom, RangeFull, RangeInclusive,
     RangeTo, RangeToInclusive,
 };
-#[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
 use core::str::FromStr;
 use core::{fmt, hash};
 
-#[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
 use crate::borrow::{Cow, ToOwned};
-#[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
 use crate::boxed::Box;
 #[cfg(not(no_rc))]
 use crate::rc::Rc;
@@ -181,7 +178,6 @@ impl Default for ByteString {
 
 // Omitted due to inference failures
 //
-// #[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
 // #[unstable(feature = "bstr", issue = "134915")]
 // impl<'a, const N: usize> From<&'a [u8; N]> for ByteString {
 //     #[inline]
@@ -190,7 +186,6 @@ impl Default for ByteString {
 //     }
 // }
 //
-// #[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
 // #[unstable(feature = "bstr", issue = "134915")]
 // impl<const N: usize> From<[u8; N]> for ByteString {
 //     #[inline]
@@ -199,7 +194,6 @@ impl Default for ByteString {
 //     }
 // }
 //
-// #[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
 // #[unstable(feature = "bstr", issue = "134915")]
 // impl<'a> From<&'a [u8]> for ByteString {
 //     #[inline]
@@ -226,7 +220,6 @@ impl From<ByteString> for Vec<u8> {
 
 // Omitted due to inference failures
 //
-// #[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
 // #[unstable(feature = "bstr", issue = "134915")]
 // impl<'a> From<&'a str> for ByteString {
 //     #[inline]
@@ -243,7 +236,6 @@ impl From<ByteString> for Vec<u8> {
 //     }
 // }
 
-#[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
 #[unstable(feature = "bstr", issue = "134915")]
 impl<'a> From<&'a ByteStr> for ByteString {
     #[inline]
@@ -252,7 +244,6 @@ impl<'a> From<&'a ByteStr> for ByteString {
     }
 }
 
-#[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
 #[unstable(feature = "bstr", issue = "134915")]
 impl<'a> From<ByteString> for Cow<'a, ByteStr> {
     #[inline]
@@ -261,7 +252,6 @@ impl<'a> From<ByteString> for Cow<'a, ByteStr> {
     }
 }
 
-#[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
 #[unstable(feature = "bstr", issue = "134915")]
 impl<'a> From<&'a ByteString> for Cow<'a, ByteStr> {
     #[inline]
@@ -330,7 +320,6 @@ impl FromIterator<ByteString> for ByteString {
     }
 }
 
-#[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
 #[unstable(feature = "bstr", issue = "134915")]
 impl FromStr for ByteString {
     type Err = core::convert::Infallible;
@@ -488,7 +477,6 @@ impl PartialEq for ByteString {
 
 macro_rules! impl_partial_eq_ord_cow {
     ($lhs:ty, $rhs:ty) => {
-        #[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
         #[allow(unused_lifetimes)]
         #[unstable(feature = "bstr", issue = "134915")]
         impl<'a> PartialEq<$rhs> for $lhs {
@@ -499,7 +487,6 @@ macro_rules! impl_partial_eq_ord_cow {
             }
         }
 
-        #[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
         #[allow(unused_lifetimes)]
         #[unstable(feature = "bstr", issue = "134915")]
         impl<'a> PartialEq<$lhs> for $rhs {
@@ -510,7 +497,6 @@ macro_rules! impl_partial_eq_ord_cow {
             }
         }
 
-        #[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
         #[allow(unused_lifetimes)]
         #[unstable(feature = "bstr", issue = "134915")]
         impl<'a> PartialOrd<$rhs> for $lhs {
@@ -521,7 +507,6 @@ macro_rules! impl_partial_eq_ord_cow {
             }
         }
 
-        #[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
         #[allow(unused_lifetimes)]
         #[unstable(feature = "bstr", issue = "134915")]
         impl<'a> PartialOrd<$lhs> for $rhs {
@@ -572,7 +557,6 @@ impl PartialOrd for ByteString {
     }
 }
 
-#[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
 #[unstable(feature = "bstr", issue = "134915")]
 impl ToOwned for ByteStr {
     type Owned = ByteString;
@@ -605,7 +589,6 @@ impl<'a> TryFrom<&'a ByteString> for &'a str {
 
 // Additional impls for `ByteStr` that require types from `alloc`:
 
-#[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
 #[unstable(feature = "bstr", issue = "134915")]
 impl Clone for Box<ByteStr> {
     #[inline]
@@ -614,7 +597,6 @@ impl Clone for Box<ByteStr> {
     }
 }
 
-#[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
 #[unstable(feature = "bstr", issue = "134915")]
 impl<'a> From<&'a ByteStr> for Cow<'a, ByteStr> {
     #[inline]
@@ -623,7 +605,6 @@ impl<'a> From<&'a ByteStr> for Cow<'a, ByteStr> {
     }
 }
 
-#[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
 #[unstable(feature = "bstr", issue = "134915")]
 impl From<Box<[u8]>> for Box<ByteStr> {
     #[inline]
@@ -633,7 +614,6 @@ impl From<Box<[u8]>> for Box<ByteStr> {
     }
 }
 
-#[cfg(not(test))] // https://github.com/rust-lang/rust/issues/135100
 #[unstable(feature = "bstr", issue = "134915")]
 impl From<Box<ByteStr>> for Box<[u8]> {
     #[inline]
diff --git a/library/alloc/src/collections/binary_heap/mod.rs b/library/alloc/src/collections/binary_heap/mod.rs
index 965fd63a529..b764b8fa5d9 100644
--- a/library/alloc/src/collections/binary_heap/mod.rs
+++ b/library/alloc/src/collections/binary_heap/mod.rs
@@ -153,7 +153,9 @@ use core::{fmt, ptr};
 use crate::alloc::Global;
 use crate::collections::TryReserveError;
 use crate::slice;
-use crate::vec::{self, AsVecIntoIter, Vec};
+#[cfg(not(test))]
+use crate::vec::AsVecIntoIter;
+use crate::vec::{self, Vec};
 
 /// A priority queue implemented with a binary heap.
 ///
@@ -1600,6 +1602,7 @@ unsafe impl<I, A: Allocator> InPlaceIterable for IntoIter<I, A> {
     const MERGE_BY: Option<NonZero<usize>> = NonZero::new(1);
 }
 
+#[cfg(not(test))]
 unsafe impl<I> AsVecIntoIter for IntoIter<I> {
     type Item = I;
 
diff --git a/library/alloc/src/collections/mod.rs b/library/alloc/src/collections/mod.rs
index 020cf4d7365..fac4d1a65ab 100644
--- a/library/alloc/src/collections/mod.rs
+++ b/library/alloc/src/collections/mod.rs
@@ -1,5 +1,8 @@
 //! Collection types.
 
+// Note: This module is also included in the alloctests crate using #[path] to
+// run the tests. See the comment there for an explanation why this is the case.
+
 #![stable(feature = "rust1", since = "1.0.0")]
 
 #[cfg(not(no_global_oom_handling))]
@@ -24,41 +27,54 @@ pub mod btree_map {
 pub mod btree_set {
     //! An ordered set based on a B-Tree.
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[cfg(not(test))]
     pub use super::btree::set::*;
 }
 
+#[cfg(not(test))]
 use core::fmt::Display;
 
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[doc(no_inline)]
+#[cfg(not(test))]
 pub use binary_heap::BinaryHeap;
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[doc(no_inline)]
+#[cfg(not(test))]
 pub use btree_map::BTreeMap;
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[doc(no_inline)]
+#[cfg(not(test))]
 pub use btree_set::BTreeSet;
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[doc(no_inline)]
+#[cfg(not(test))]
 pub use linked_list::LinkedList;
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[doc(no_inline)]
+#[cfg(not(test))]
 pub use vec_deque::VecDeque;
 
+#[cfg(not(test))]
 use crate::alloc::{Layout, LayoutError};
 
 /// The error type for `try_reserve` methods.
 #[derive(Clone, PartialEq, Eq, Debug)]
 #[stable(feature = "try_reserve", since = "1.57.0")]
+#[cfg(not(test))]
 pub struct TryReserveError {
     kind: TryReserveErrorKind,
 }
 
+#[cfg(test)]
+pub use realalloc::collections::TryReserveError;
+
+#[cfg(not(test))]
 impl TryReserveError {
     /// Details about the allocation that caused the error
     #[inline]
@@ -80,6 +96,7 @@ impl TryReserveError {
     reason = "Uncertain how much info should be exposed",
     issue = "48043"
 )]
+#[cfg(not(test))]
 pub enum TryReserveErrorKind {
     /// Error due to the computed capacity exceeding the collection's maximum
     /// (usually `isize::MAX` bytes).
@@ -103,11 +120,15 @@ pub enum TryReserveErrorKind {
     },
 }
 
+#[cfg(test)]
+pub use realalloc::collections::TryReserveErrorKind;
+
 #[unstable(
     feature = "try_reserve_kind",
     reason = "Uncertain how much info should be exposed",
     issue = "48043"
 )]
+#[cfg(not(test))]
 impl From<TryReserveErrorKind> for TryReserveError {
     #[inline]
     fn from(kind: TryReserveErrorKind) -> Self {
@@ -116,6 +137,7 @@ impl From<TryReserveErrorKind> for TryReserveError {
 }
 
 #[unstable(feature = "try_reserve_kind", reason = "new API", issue = "48043")]
+#[cfg(not(test))]
 impl From<LayoutError> for TryReserveErrorKind {
     /// Always evaluates to [`TryReserveErrorKind::CapacityOverflow`].
     #[inline]
@@ -125,6 +147,7 @@ impl From<LayoutError> for TryReserveErrorKind {
 }
 
 #[stable(feature = "try_reserve", since = "1.57.0")]
+#[cfg(not(test))]
 impl Display for TryReserveError {
     fn fmt(
         &self,
@@ -152,4 +175,5 @@ trait SpecExtend<I: IntoIterator> {
 }
 
 #[stable(feature = "try_reserve", since = "1.57.0")]
+#[cfg(not(test))]
 impl core::error::Error for TryReserveError {}
diff --git a/library/alloc/src/collections/vec_deque/mod.rs b/library/alloc/src/collections/vec_deque/mod.rs
index 299c8b8679e..f8844e2d3a5 100644
--- a/library/alloc/src/collections/vec_deque/mod.rs
+++ b/library/alloc/src/collections/vec_deque/mod.rs
@@ -645,6 +645,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// initialized rather than only supporting `0..len`.  Requires that
     /// `initialized.start` ≤ `initialized.end` ≤ `capacity`.
     #[inline]
+    #[cfg(not(test))]
     pub(crate) unsafe fn from_contiguous_raw_parts_in(
         ptr: *mut T,
         initialized: Range<usize>,
diff --git a/library/alloc/src/collections/vec_deque/spec_extend.rs b/library/alloc/src/collections/vec_deque/spec_extend.rs
index d246385ca84..7c7072c4c3a 100644
--- a/library/alloc/src/collections/vec_deque/spec_extend.rs
+++ b/library/alloc/src/collections/vec_deque/spec_extend.rs
@@ -3,6 +3,7 @@ use core::slice;
 
 use super::VecDeque;
 use crate::alloc::Allocator;
+#[cfg(not(test))]
 use crate::vec;
 
 // Specialization trait used for VecDeque::extend
@@ -78,6 +79,7 @@ where
     }
 }
 
+#[cfg(not(test))]
 impl<T, A: Allocator> SpecExtend<T, vec::IntoIter<T>> for VecDeque<T, A> {
     #[track_caller]
     fn spec_extend(&mut self, mut iterator: vec::IntoIter<T>) {
diff --git a/library/alloc/src/collections/vec_deque/spec_from_iter.rs b/library/alloc/src/collections/vec_deque/spec_from_iter.rs
index 1efe84d6d7d..c80a30c2103 100644
--- a/library/alloc/src/collections/vec_deque/spec_from_iter.rs
+++ b/library/alloc/src/collections/vec_deque/spec_from_iter.rs
@@ -19,6 +19,7 @@ where
     }
 }
 
+#[cfg(not(test))]
 impl<T> SpecFromIter<T, crate::vec::IntoIter<T>> for VecDeque<T> {
     #[inline]
     fn spec_from_iter(iterator: crate::vec::IntoIter<T>) -> Self {
diff --git a/library/alloc/src/ffi/c_str.rs b/library/alloc/src/ffi/c_str.rs
index fd93045a5ac..f6743c65710 100644
--- a/library/alloc/src/ffi/c_str.rs
+++ b/library/alloc/src/ffi/c_str.rs
@@ -10,7 +10,6 @@ use core::{fmt, mem, ops, ptr, slice};
 use crate::borrow::{Cow, ToOwned};
 use crate::boxed::Box;
 use crate::rc::Rc;
-use crate::slice::hack::into_vec;
 use crate::string::String;
 #[cfg(target_has_atomic = "ptr")]
 use crate::sync::Arc;
@@ -103,7 +102,7 @@ use crate::vec::Vec;
 /// of `CString` instances can lead to invalid memory accesses, memory leaks,
 /// and other memory errors.
 #[derive(PartialEq, PartialOrd, Eq, Ord, Hash, Clone)]
-#[cfg_attr(not(test), rustc_diagnostic_item = "cstring_type")]
+#[rustc_diagnostic_item = "cstring_type"]
 #[stable(feature = "alloc_c_string", since = "1.64.0")]
 pub struct CString {
     // Invariant 1: the slice ends with a zero byte and has a length of at least one.
@@ -491,7 +490,7 @@ impl CString {
     #[must_use = "`self` will be dropped if the result is not used"]
     #[stable(feature = "cstring_into", since = "1.7.0")]
     pub fn into_bytes(self) -> Vec<u8> {
-        let mut vec = into_vec(self.into_inner());
+        let mut vec = self.into_inner().into_vec();
         let _nul = vec.pop();
         debug_assert_eq!(_nul, Some(0u8));
         vec
@@ -512,7 +511,7 @@ impl CString {
     #[must_use = "`self` will be dropped if the result is not used"]
     #[stable(feature = "cstring_into", since = "1.7.0")]
     pub fn into_bytes_with_nul(self) -> Vec<u8> {
-        into_vec(self.into_inner())
+        self.into_inner().into_vec()
     }
 
     /// Returns the contents of this `CString` as a slice of bytes.
@@ -573,7 +572,7 @@ impl CString {
     #[inline]
     #[must_use]
     #[stable(feature = "as_c_str", since = "1.20.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "cstring_as_c_str")]
+    #[rustc_diagnostic_item = "cstring_as_c_str"]
     pub fn as_c_str(&self) -> &CStr {
         &*self
     }
@@ -755,7 +754,6 @@ impl<'a> From<Cow<'a, CStr>> for CString {
     }
 }
 
-#[cfg(not(test))]
 #[stable(feature = "box_from_c_str", since = "1.17.0")]
 impl From<&CStr> for Box<CStr> {
     /// Converts a `&CStr` into a `Box<CStr>`,
@@ -766,7 +764,6 @@ impl From<&CStr> for Box<CStr> {
     }
 }
 
-#[cfg(not(test))]
 #[stable(feature = "box_from_mut_slice", since = "1.84.0")]
 impl From<&mut CStr> for Box<CStr> {
     /// Converts a `&mut CStr` into a `Box<CStr>`,
@@ -845,7 +842,6 @@ impl TryFrom<CString> for String {
     }
 }
 
-#[cfg(not(test))]
 #[stable(feature = "more_box_slice_clone", since = "1.29.0")]
 impl Clone for Box<CStr> {
     #[inline]
@@ -971,7 +967,6 @@ impl Default for Rc<CStr> {
     }
 }
 
-#[cfg(not(test))]
 #[stable(feature = "default_box_extra", since = "1.17.0")]
 impl Default for Box<CStr> {
     fn default() -> Box<CStr> {
@@ -1080,7 +1075,7 @@ impl ToOwned for CStr {
     }
 
     fn clone_into(&self, target: &mut CString) {
-        let mut b = into_vec(mem::take(&mut target.inner));
+        let mut b = mem::take(&mut target.inner).into_vec();
         self.to_bytes_with_nul().clone_into(&mut b);
         target.inner = b.into_boxed_slice();
     }
@@ -1113,7 +1108,6 @@ impl AsRef<CStr> for CString {
     }
 }
 
-#[cfg(not(test))]
 impl CStr {
     /// Converts a `CStr` into a <code>[Cow]<[str]></code>.
     ///
diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index 265b68d3b0e..f0cdb1e4e0f 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -93,7 +93,6 @@
 //
 // Library features:
 // tidy-alphabetical-start
-#![cfg_attr(test, feature(str_as_str))]
 #![feature(alloc_layout_extra)]
 #![feature(allocator_api)]
 #![feature(array_chunks)]
@@ -161,13 +160,11 @@
 //
 // Language features:
 // tidy-alphabetical-start
-#![cfg_attr(not(test), feature(coroutine_trait))]
-#![cfg_attr(test, feature(panic_update_hook))]
-#![cfg_attr(test, feature(test))]
 #![feature(allocator_internals)]
 #![feature(allow_internal_unstable)]
 #![feature(cfg_sanitize)]
 #![feature(const_precise_live_drops)]
+#![feature(coroutine_trait)]
 #![feature(decl_macro)]
 #![feature(dropck_eyepatch)]
 #![feature(fundamental)]
@@ -200,15 +197,6 @@
 // from other crates, but since this can only appear for lang items, it doesn't seem worth fixing.
 #![feature(intra_doc_pointers)]
 
-// Allow testing this library
-#[cfg(test)]
-#[macro_use]
-extern crate std;
-#[cfg(test)]
-extern crate test;
-#[cfg(test)]
-mod testing;
-
 // Module with internal macros used by other modules (needs to be included before other modules).
 #[macro_use]
 mod macros;
@@ -216,7 +204,6 @@ mod macros;
 mod raw_vec;
 
 // Heaps provided for low-level allocation strategies
-
 pub mod alloc;
 
 // Primitive types using the heaps above
@@ -224,13 +211,8 @@ pub mod alloc;
 // Need to conditionally define the mod from `boxed.rs` to avoid
 // duplicating the lang-items when building in test cfg; but also need
 // to allow code to have `use boxed::Box;` declarations.
-#[cfg(not(test))]
-pub mod boxed;
-#[cfg(test)]
-mod boxed {
-    pub(crate) use std::boxed::Box;
-}
 pub mod borrow;
+pub mod boxed;
 #[unstable(feature = "bstr", issue = "134915")]
 pub mod bstr;
 pub mod collections;
@@ -254,20 +236,3 @@ pub mod __export {
     pub use core::format_args;
     pub use core::hint::must_use;
 }
-
-#[cfg(test)]
-#[allow(dead_code)] // Not used in all configurations
-pub(crate) mod test_helpers {
-    /// Copied from `std::test_helpers::test_rng`, since these tests rely on the
-    /// seed not being the same for every RNG invocation too.
-    pub(crate) fn test_rng() -> rand_xorshift::XorShiftRng {
-        use std::hash::{BuildHasher, Hash, Hasher};
-        let mut hasher = std::hash::RandomState::new().build_hasher();
-        std::panic::Location::caller().hash(&mut hasher);
-        let hc64 = hasher.finish();
-        let seed_vec =
-            hc64.to_le_bytes().into_iter().chain(0u8..8).collect::<crate::vec::Vec<u8>>();
-        let seed: [u8; 16] = seed_vec.as_slice().try_into().unwrap();
-        rand::SeedableRng::from_seed(seed)
-    }
-}
diff --git a/library/alloc/src/macros.rs b/library/alloc/src/macros.rs
index c000fd6f4ef..214192b8c9a 100644
--- a/library/alloc/src/macros.rs
+++ b/library/alloc/src/macros.rs
@@ -34,7 +34,7 @@
 /// be mindful of side effects.
 ///
 /// [`Vec`]: crate::vec::Vec
-#[cfg(all(not(no_global_oom_handling), not(test)))]
+#[cfg(not(no_global_oom_handling))]
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_diagnostic_item = "vec_macro"]
@@ -55,25 +55,6 @@ macro_rules! vec {
     );
 }
 
-// HACK(japaric): with cfg(test) the inherent `[T]::into_vec` method, which is
-// required for this macro definition, is not available. Instead use the
-// `slice::into_vec`  function which is only available with cfg(test)
-// NB see the slice::hack module in slice.rs for more information
-#[cfg(all(not(no_global_oom_handling), test))]
-#[allow(unused_macro_rules)]
-macro_rules! vec {
-    () => (
-        $crate::vec::Vec::new()
-    );
-    ($elem:expr; $n:expr) => (
-        $crate::vec::from_elem($elem, $n)
-    );
-    ($($x:expr),*) => (
-        $crate::slice::into_vec($crate::boxed::Box::new([$($x),*]))
-    );
-    ($($x:expr,)*) => (vec![$($x),*])
-}
-
 /// Creates a `String` using interpolation of runtime expressions.
 ///
 /// The first argument `format!` receives is a format string. This must be a string
@@ -120,7 +101,7 @@ macro_rules! vec {
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[allow_internal_unstable(hint_must_use, liballoc_internals)]
-#[cfg_attr(not(test), rustc_diagnostic_item = "format_macro")]
+#[rustc_diagnostic_item = "format_macro"]
 macro_rules! format {
     ($($arg:tt)*) => {
         $crate::__export::must_use({
diff --git a/library/alloc/src/raw_vec.rs b/library/alloc/src/raw_vec/mod.rs
index 70f32fbaab4..99ebc5c4bfc 100644
--- a/library/alloc/src/raw_vec.rs
+++ b/library/alloc/src/raw_vec/mod.rs
@@ -1,4 +1,8 @@
 #![unstable(feature = "raw_vec_internals", reason = "unstable const warnings", issue = "none")]
+#![cfg_attr(test, allow(dead_code))]
+
+// Note: This module is also included in the alloctests crate using #[path] to
+// run the tests. See the comment there for an explanation why this is the case.
 
 use core::marker::PhantomData;
 use core::mem::{ManuallyDrop, MaybeUninit, SizedTypeProperties};
diff --git a/library/alloc/src/rc.rs b/library/alloc/src/rc.rs
index 5847bd8f281..fc1cee28d03 100644
--- a/library/alloc/src/rc.rs
+++ b/library/alloc/src/rc.rs
@@ -263,23 +263,17 @@ use core::ptr::{self, NonNull, drop_in_place};
 #[cfg(not(no_global_oom_handling))]
 use core::slice::from_raw_parts_mut;
 use core::{borrow, fmt, hint};
-#[cfg(test)]
-use std::boxed::Box;
 
 #[cfg(not(no_global_oom_handling))]
 use crate::alloc::handle_alloc_error;
 use crate::alloc::{AllocError, Allocator, Global, Layout};
 use crate::borrow::{Cow, ToOwned};
-#[cfg(not(test))]
 use crate::boxed::Box;
 #[cfg(not(no_global_oom_handling))]
 use crate::string::String;
 #[cfg(not(no_global_oom_handling))]
 use crate::vec::Vec;
 
-#[cfg(test)]
-mod tests;
-
 // This is repr(C) to future-proof against possible field-reordering, which
 // would interfere with otherwise safe [into|from]_raw() of transmutable
 // inner types.
@@ -310,7 +304,7 @@ fn rc_inner_layout_for_value_layout(layout: Layout) -> Layout {
 ///
 /// [get_mut]: Rc::get_mut
 #[doc(search_unbox)]
-#[cfg_attr(not(test), rustc_diagnostic_item = "Rc")]
+#[rustc_diagnostic_item = "Rc"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_insignificant_dtor]
 pub struct Rc<
@@ -2988,7 +2982,7 @@ impl<T, I: iter::TrustedLen<Item = T>> ToRcSlice<T> for I {
 ///
 /// [`upgrade`]: Weak::upgrade
 #[stable(feature = "rc_weak", since = "1.4.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "RcWeak")]
+#[rustc_diagnostic_item = "RcWeak"]
 pub struct Weak<
     T: ?Sized,
     #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global,
diff --git a/library/alloc/src/rc/tests.rs b/library/alloc/src/rc/tests.rs
deleted file mode 100644
index 2210a7c24c0..00000000000
--- a/library/alloc/src/rc/tests.rs
+++ /dev/null
@@ -1,664 +0,0 @@
-use std::cell::RefCell;
-use std::clone::Clone;
-
-use super::*;
-
-#[test]
-fn test_clone() {
-    let x = Rc::new(RefCell::new(5));
-    let y = x.clone();
-    *x.borrow_mut() = 20;
-    assert_eq!(*y.borrow(), 20);
-}
-
-#[test]
-fn test_simple() {
-    let x = Rc::new(5);
-    assert_eq!(*x, 5);
-}
-
-#[test]
-fn test_simple_clone() {
-    let x = Rc::new(5);
-    let y = x.clone();
-    assert_eq!(*x, 5);
-    assert_eq!(*y, 5);
-}
-
-#[test]
-fn test_destructor() {
-    let x: Rc<Box<_>> = Rc::new(Box::new(5));
-    assert_eq!(**x, 5);
-}
-
-#[test]
-fn test_live() {
-    let x = Rc::new(5);
-    let y = Rc::downgrade(&x);
-    assert!(y.upgrade().is_some());
-}
-
-#[test]
-fn test_dead() {
-    let x = Rc::new(5);
-    let y = Rc::downgrade(&x);
-    drop(x);
-    assert!(y.upgrade().is_none());
-}
-
-#[test]
-fn weak_self_cyclic() {
-    struct Cycle {
-        x: RefCell<Option<Weak<Cycle>>>,
-    }
-
-    let a = Rc::new(Cycle { x: RefCell::new(None) });
-    let b = Rc::downgrade(&a.clone());
-    *a.x.borrow_mut() = Some(b);
-
-    // hopefully we don't double-free (or leak)...
-}
-
-#[test]
-fn is_unique() {
-    let x = Rc::new(3);
-    assert!(Rc::is_unique(&x));
-    let y = x.clone();
-    assert!(!Rc::is_unique(&x));
-    drop(y);
-    assert!(Rc::is_unique(&x));
-    let w = Rc::downgrade(&x);
-    assert!(!Rc::is_unique(&x));
-    drop(w);
-    assert!(Rc::is_unique(&x));
-}
-
-#[test]
-fn test_strong_count() {
-    let a = Rc::new(0);
-    assert!(Rc::strong_count(&a) == 1);
-    let w = Rc::downgrade(&a);
-    assert!(Rc::strong_count(&a) == 1);
-    let b = w.upgrade().expect("upgrade of live rc failed");
-    assert!(Rc::strong_count(&b) == 2);
-    assert!(Rc::strong_count(&a) == 2);
-    drop(w);
-    drop(a);
-    assert!(Rc::strong_count(&b) == 1);
-    let c = b.clone();
-    assert!(Rc::strong_count(&b) == 2);
-    assert!(Rc::strong_count(&c) == 2);
-}
-
-#[test]
-fn test_weak_count() {
-    let a = Rc::new(0);
-    assert!(Rc::strong_count(&a) == 1);
-    assert!(Rc::weak_count(&a) == 0);
-    let w = Rc::downgrade(&a);
-    assert!(Rc::strong_count(&a) == 1);
-    assert!(Rc::weak_count(&a) == 1);
-    drop(w);
-    assert!(Rc::strong_count(&a) == 1);
-    assert!(Rc::weak_count(&a) == 0);
-    let c = a.clone();
-    assert!(Rc::strong_count(&a) == 2);
-    assert!(Rc::weak_count(&a) == 0);
-    drop(c);
-}
-
-#[test]
-fn weak_counts() {
-    assert_eq!(Weak::weak_count(&Weak::<u64>::new()), 0);
-    assert_eq!(Weak::strong_count(&Weak::<u64>::new()), 0);
-
-    let a = Rc::new(0);
-    let w = Rc::downgrade(&a);
-    assert_eq!(Weak::strong_count(&w), 1);
-    assert_eq!(Weak::weak_count(&w), 1);
-    let w2 = w.clone();
-    assert_eq!(Weak::strong_count(&w), 1);
-    assert_eq!(Weak::weak_count(&w), 2);
-    assert_eq!(Weak::strong_count(&w2), 1);
-    assert_eq!(Weak::weak_count(&w2), 2);
-    drop(w);
-    assert_eq!(Weak::strong_count(&w2), 1);
-    assert_eq!(Weak::weak_count(&w2), 1);
-    let a2 = a.clone();
-    assert_eq!(Weak::strong_count(&w2), 2);
-    assert_eq!(Weak::weak_count(&w2), 1);
-    drop(a2);
-    drop(a);
-    assert_eq!(Weak::strong_count(&w2), 0);
-    assert_eq!(Weak::weak_count(&w2), 0);
-    drop(w2);
-}
-
-#[test]
-fn try_unwrap() {
-    let x = Rc::new(3);
-    assert_eq!(Rc::try_unwrap(x), Ok(3));
-    let x = Rc::new(4);
-    let _y = x.clone();
-    assert_eq!(Rc::try_unwrap(x), Err(Rc::new(4)));
-    let x = Rc::new(5);
-    let _w = Rc::downgrade(&x);
-    assert_eq!(Rc::try_unwrap(x), Ok(5));
-}
-
-#[test]
-fn into_inner() {
-    let x = Rc::new(3);
-    assert_eq!(Rc::into_inner(x), Some(3));
-
-    let x = Rc::new(4);
-    let y = Rc::clone(&x);
-    assert_eq!(Rc::into_inner(x), None);
-    assert_eq!(Rc::into_inner(y), Some(4));
-
-    let x = Rc::new(5);
-    let _w = Rc::downgrade(&x);
-    assert_eq!(Rc::into_inner(x), Some(5));
-}
-
-#[test]
-fn into_from_raw() {
-    let x = Rc::new(Box::new("hello"));
-    let y = x.clone();
-
-    let x_ptr = Rc::into_raw(x);
-    drop(y);
-    unsafe {
-        assert_eq!(**x_ptr, "hello");
-
-        let x = Rc::from_raw(x_ptr);
-        assert_eq!(**x, "hello");
-
-        assert_eq!(Rc::try_unwrap(x).map(|x| *x), Ok("hello"));
-    }
-}
-
-#[test]
-fn test_into_from_raw_unsized() {
-    use std::fmt::Display;
-    use std::string::ToString;
-
-    let rc: Rc<str> = Rc::from("foo");
-
-    let ptr = Rc::into_raw(rc.clone());
-    let rc2 = unsafe { Rc::from_raw(ptr) };
-
-    assert_eq!(unsafe { &*ptr }, "foo");
-    assert_eq!(rc, rc2);
-
-    let rc: Rc<dyn Display> = Rc::new(123);
-
-    let ptr = Rc::into_raw(rc.clone());
-    let rc2 = unsafe { Rc::from_raw(ptr) };
-
-    assert_eq!(unsafe { &*ptr }.to_string(), "123");
-    assert_eq!(rc2.to_string(), "123");
-}
-
-#[test]
-fn into_from_weak_raw() {
-    let x = Rc::new(Box::new("hello"));
-    let y = Rc::downgrade(&x);
-
-    let y_ptr = Weak::into_raw(y);
-    unsafe {
-        assert_eq!(**y_ptr, "hello");
-
-        let y = Weak::from_raw(y_ptr);
-        let y_up = Weak::upgrade(&y).unwrap();
-        assert_eq!(**y_up, "hello");
-        drop(y_up);
-
-        assert_eq!(Rc::try_unwrap(x).map(|x| *x), Ok("hello"));
-    }
-}
-
-#[test]
-fn test_into_from_weak_raw_unsized() {
-    use std::fmt::Display;
-    use std::string::ToString;
-
-    let arc: Rc<str> = Rc::from("foo");
-    let weak: Weak<str> = Rc::downgrade(&arc);
-
-    let ptr = Weak::into_raw(weak.clone());
-    let weak2 = unsafe { Weak::from_raw(ptr) };
-
-    assert_eq!(unsafe { &*ptr }, "foo");
-    assert!(weak.ptr_eq(&weak2));
-
-    let arc: Rc<dyn Display> = Rc::new(123);
-    let weak: Weak<dyn Display> = Rc::downgrade(&arc);
-
-    let ptr = Weak::into_raw(weak.clone());
-    let weak2 = unsafe { Weak::from_raw(ptr) };
-
-    assert_eq!(unsafe { &*ptr }.to_string(), "123");
-    assert!(weak.ptr_eq(&weak2));
-}
-
-#[test]
-fn get_mut() {
-    let mut x = Rc::new(3);
-    *Rc::get_mut(&mut x).unwrap() = 4;
-    assert_eq!(*x, 4);
-    let y = x.clone();
-    assert!(Rc::get_mut(&mut x).is_none());
-    drop(y);
-    assert!(Rc::get_mut(&mut x).is_some());
-    let _w = Rc::downgrade(&x);
-    assert!(Rc::get_mut(&mut x).is_none());
-}
-
-#[test]
-fn test_cowrc_clone_make_unique() {
-    let mut cow0 = Rc::new(75);
-    let mut cow1 = cow0.clone();
-    let mut cow2 = cow1.clone();
-
-    assert!(75 == *Rc::make_mut(&mut cow0));
-    assert!(75 == *Rc::make_mut(&mut cow1));
-    assert!(75 == *Rc::make_mut(&mut cow2));
-
-    *Rc::make_mut(&mut cow0) += 1;
-    *Rc::make_mut(&mut cow1) += 2;
-    *Rc::make_mut(&mut cow2) += 3;
-
-    assert!(76 == *cow0);
-    assert!(77 == *cow1);
-    assert!(78 == *cow2);
-
-    // none should point to the same backing memory
-    assert!(*cow0 != *cow1);
-    assert!(*cow0 != *cow2);
-    assert!(*cow1 != *cow2);
-}
-
-#[test]
-fn test_cowrc_clone_unique2() {
-    let mut cow0 = Rc::new(75);
-    let cow1 = cow0.clone();
-    let cow2 = cow1.clone();
-
-    assert!(75 == *cow0);
-    assert!(75 == *cow1);
-    assert!(75 == *cow2);
-
-    *Rc::make_mut(&mut cow0) += 1;
-
-    assert!(76 == *cow0);
-    assert!(75 == *cow1);
-    assert!(75 == *cow2);
-
-    // cow1 and cow2 should share the same contents
-    // cow0 should have a unique reference
-    assert!(*cow0 != *cow1);
-    assert!(*cow0 != *cow2);
-    assert!(*cow1 == *cow2);
-}
-
-#[test]
-fn test_cowrc_clone_weak() {
-    let mut cow0 = Rc::new(75);
-    let cow1_weak = Rc::downgrade(&cow0);
-
-    assert!(75 == *cow0);
-    assert!(75 == *cow1_weak.upgrade().unwrap());
-
-    *Rc::make_mut(&mut cow0) += 1;
-
-    assert!(76 == *cow0);
-    assert!(cow1_weak.upgrade().is_none());
-}
-
-/// This is similar to the doc-test for `Rc::make_mut()`, but on an unsized type (slice).
-#[test]
-fn test_cowrc_unsized() {
-    use std::rc::Rc;
-
-    let mut data: Rc<[i32]> = Rc::new([10, 20, 30]);
-
-    Rc::make_mut(&mut data)[0] += 1; // Won't clone anything
-    let mut other_data = Rc::clone(&data); // Won't clone inner data
-    Rc::make_mut(&mut data)[1] += 1; // Clones inner data
-    Rc::make_mut(&mut data)[2] += 1; // Won't clone anything
-    Rc::make_mut(&mut other_data)[0] *= 10; // Won't clone anything
-
-    // Now `data` and `other_data` point to different allocations.
-    assert_eq!(*data, [11, 21, 31]);
-    assert_eq!(*other_data, [110, 20, 30]);
-}
-
-#[test]
-fn test_show() {
-    let foo = Rc::new(75);
-    assert_eq!(format!("{foo:?}"), "75");
-}
-
-#[test]
-fn test_unsized() {
-    let foo: Rc<[i32]> = Rc::new([1, 2, 3]);
-    assert_eq!(foo, foo.clone());
-}
-
-#[test]
-fn test_maybe_thin_unsized() {
-    // If/when custom thin DSTs exist, this test should be updated to use one
-    use std::ffi::CStr;
-
-    let x: Rc<CStr> = Rc::from(c"swordfish");
-    assert_eq!(format!("{x:?}"), "\"swordfish\"");
-    let y: Weak<CStr> = Rc::downgrade(&x);
-    drop(x);
-
-    // At this point, the weak points to a dropped DST
-    assert!(y.upgrade().is_none());
-    // But we still need to be able to get the alloc layout to drop.
-    // CStr has no drop glue, but custom DSTs might, and need to work.
-    drop(y);
-}
-
-#[test]
-fn test_from_owned() {
-    let foo = 123;
-    let foo_rc = Rc::from(foo);
-    assert!(123 == *foo_rc);
-}
-
-#[test]
-fn test_new_weak() {
-    let foo: Weak<usize> = Weak::new();
-    assert!(foo.upgrade().is_none());
-}
-
-#[test]
-fn test_ptr_eq() {
-    let five = Rc::new(5);
-    let same_five = five.clone();
-    let other_five = Rc::new(5);
-
-    assert!(Rc::ptr_eq(&five, &same_five));
-    assert!(!Rc::ptr_eq(&five, &other_five));
-}
-
-#[test]
-fn test_from_str() {
-    let r: Rc<str> = Rc::from("foo");
-
-    assert_eq!(&r[..], "foo");
-}
-
-#[test]
-fn test_copy_from_slice() {
-    let s: &[u32] = &[1, 2, 3];
-    let r: Rc<[u32]> = Rc::from(s);
-
-    assert_eq!(&r[..], [1, 2, 3]);
-}
-
-#[test]
-fn test_clone_from_slice() {
-    #[derive(Clone, Debug, Eq, PartialEq)]
-    struct X(u32);
-
-    let s: &[X] = &[X(1), X(2), X(3)];
-    let r: Rc<[X]> = Rc::from(s);
-
-    assert_eq!(&r[..], s);
-}
-
-#[test]
-#[should_panic]
-fn test_clone_from_slice_panic() {
-    use std::string::{String, ToString};
-
-    struct Fail(u32, String);
-
-    impl Clone for Fail {
-        fn clone(&self) -> Fail {
-            if self.0 == 2 {
-                panic!();
-            }
-            Fail(self.0, self.1.clone())
-        }
-    }
-
-    let s: &[Fail] =
-        &[Fail(0, "foo".to_string()), Fail(1, "bar".to_string()), Fail(2, "baz".to_string())];
-
-    // Should panic, but not cause memory corruption
-    let _r: Rc<[Fail]> = Rc::from(s);
-}
-
-#[test]
-fn test_from_box() {
-    let b: Box<u32> = Box::new(123);
-    let r: Rc<u32> = Rc::from(b);
-
-    assert_eq!(*r, 123);
-}
-
-#[test]
-fn test_from_box_str() {
-    use std::string::String;
-
-    let s = String::from("foo").into_boxed_str();
-    assert_eq!((&&&s).as_str(), "foo");
-
-    let r: Rc<str> = Rc::from(s);
-    assert_eq!((&r).as_str(), "foo");
-    assert_eq!(r.as_str(), "foo");
-
-    assert_eq!(&r[..], "foo");
-}
-
-#[test]
-fn test_from_box_slice() {
-    let s = vec![1, 2, 3].into_boxed_slice();
-    let r: Rc<[u32]> = Rc::from(s);
-
-    assert_eq!(&r[..], [1, 2, 3]);
-}
-
-#[test]
-fn test_from_box_trait() {
-    use std::fmt::Display;
-    use std::string::ToString;
-
-    let b: Box<dyn Display> = Box::new(123);
-    let r: Rc<dyn Display> = Rc::from(b);
-
-    assert_eq!(r.to_string(), "123");
-}
-
-#[test]
-fn test_from_box_trait_zero_sized() {
-    use std::fmt::Debug;
-
-    let b: Box<dyn Debug> = Box::new(());
-    let r: Rc<dyn Debug> = Rc::from(b);
-
-    assert_eq!(format!("{r:?}"), "()");
-}
-
-#[test]
-fn test_from_vec() {
-    let v = vec![1, 2, 3];
-    let r: Rc<[u32]> = Rc::from(v);
-
-    assert_eq!(&r[..], [1, 2, 3]);
-}
-
-#[test]
-fn test_downcast() {
-    use std::any::Any;
-
-    let r1: Rc<dyn Any> = Rc::new(i32::MAX);
-    let r2: Rc<dyn Any> = Rc::new("abc");
-
-    assert!(r1.clone().downcast::<u32>().is_err());
-
-    let r1i32 = r1.downcast::<i32>();
-    assert!(r1i32.is_ok());
-    assert_eq!(r1i32.unwrap(), Rc::new(i32::MAX));
-
-    assert!(r2.clone().downcast::<i32>().is_err());
-
-    let r2str = r2.downcast::<&'static str>();
-    assert!(r2str.is_ok());
-    assert_eq!(r2str.unwrap(), Rc::new("abc"));
-}
-
-#[test]
-fn test_array_from_slice() {
-    let v = vec![1, 2, 3];
-    let r: Rc<[u32]> = Rc::from(v);
-
-    let a: Result<Rc<[u32; 3]>, _> = r.clone().try_into();
-    assert!(a.is_ok());
-
-    let a: Result<Rc<[u32; 2]>, _> = r.clone().try_into();
-    assert!(a.is_err());
-}
-
-#[test]
-fn test_rc_cyclic_with_zero_refs() {
-    struct ZeroRefs {
-        inner: Weak<ZeroRefs>,
-    }
-
-    let zero_refs = Rc::new_cyclic(|inner| {
-        assert_eq!(inner.strong_count(), 0);
-        assert!(inner.upgrade().is_none());
-        ZeroRefs { inner: Weak::new() }
-    });
-
-    assert_eq!(Rc::strong_count(&zero_refs), 1);
-    assert_eq!(Rc::weak_count(&zero_refs), 0);
-    assert_eq!(zero_refs.inner.strong_count(), 0);
-    assert_eq!(zero_refs.inner.weak_count(), 0);
-}
-
-#[test]
-fn test_rc_cyclic_with_one_ref() {
-    struct OneRef {
-        inner: Weak<OneRef>,
-    }
-
-    let one_ref = Rc::new_cyclic(|inner| {
-        assert_eq!(inner.strong_count(), 0);
-        assert!(inner.upgrade().is_none());
-        OneRef { inner: inner.clone() }
-    });
-
-    assert_eq!(Rc::strong_count(&one_ref), 1);
-    assert_eq!(Rc::weak_count(&one_ref), 1);
-
-    let one_ref2 = Weak::upgrade(&one_ref.inner).unwrap();
-    assert!(Rc::ptr_eq(&one_ref, &one_ref2));
-
-    assert_eq!(one_ref.inner.strong_count(), 2);
-    assert_eq!(one_ref.inner.weak_count(), 1);
-}
-
-#[test]
-fn test_rc_cyclic_with_two_ref() {
-    struct TwoRefs {
-        inner: Weak<TwoRefs>,
-        inner1: Weak<TwoRefs>,
-    }
-
-    let two_refs = Rc::new_cyclic(|inner| {
-        assert_eq!(inner.strong_count(), 0);
-        assert!(inner.upgrade().is_none());
-        TwoRefs { inner: inner.clone(), inner1: inner.clone() }
-    });
-
-    assert_eq!(Rc::strong_count(&two_refs), 1);
-    assert_eq!(Rc::weak_count(&two_refs), 2);
-
-    let two_ref3 = Weak::upgrade(&two_refs.inner).unwrap();
-    assert!(Rc::ptr_eq(&two_refs, &two_ref3));
-
-    let two_ref2 = Weak::upgrade(&two_refs.inner1).unwrap();
-    assert!(Rc::ptr_eq(&two_refs, &two_ref2));
-
-    assert_eq!(Rc::strong_count(&two_refs), 3);
-    assert_eq!(Rc::weak_count(&two_refs), 2);
-}
-
-#[test]
-fn test_unique_rc_weak() {
-    let rc = UniqueRc::new(42);
-    let weak = UniqueRc::downgrade(&rc);
-    assert!(weak.upgrade().is_none());
-
-    let _rc = UniqueRc::into_rc(rc);
-    assert_eq!(*weak.upgrade().unwrap(), 42);
-}
-
-#[test]
-fn test_unique_rc_drop_weak() {
-    let rc = UniqueRc::new(42);
-    let weak = UniqueRc::downgrade(&rc);
-    mem::drop(weak);
-
-    let rc = UniqueRc::into_rc(rc);
-    assert_eq!(*rc, 42);
-}
-
-#[test]
-fn test_unique_rc_drops_contents() {
-    let mut dropped = false;
-    struct DropMe<'a>(&'a mut bool);
-    impl Drop for DropMe<'_> {
-        fn drop(&mut self) {
-            *self.0 = true;
-        }
-    }
-    {
-        let rc = UniqueRc::new(DropMe(&mut dropped));
-        drop(rc);
-    }
-    assert!(dropped);
-}
-
-/// Exercise the non-default allocator usage.
-#[test]
-fn test_unique_rc_with_alloc_drops_contents() {
-    let mut dropped = false;
-    struct DropMe<'a>(&'a mut bool);
-    impl Drop for DropMe<'_> {
-        fn drop(&mut self) {
-            *self.0 = true;
-        }
-    }
-    {
-        let rc = UniqueRc::new_in(DropMe(&mut dropped), std::alloc::System);
-        drop(rc);
-    }
-    assert!(dropped);
-}
-
-#[test]
-fn test_unique_rc_weak_clone_holding_ref() {
-    let mut v = UniqueRc::new(0u8);
-    let w = UniqueRc::downgrade(&v);
-    let r = &mut *v;
-    let _ = w.clone(); // touch weak count
-    *r = 123;
-}
-
-#[test]
-fn test_unique_rc_unsizing_coercion() {
-    let mut rc: UniqueRc<[u8]> = UniqueRc::new([0u8; 3]);
-    assert_eq!(rc.len(), 3);
-    rc[0] = 123;
-    let rc: Rc<[u8]> = UniqueRc::into_rc(rc);
-    assert_eq!(*rc, [123, 0, 0]);
-}
diff --git a/library/alloc/src/slice.rs b/library/alloc/src/slice.rs
index 8baf9685062..7c5d22e1ee9 100644
--- a/library/alloc/src/slice.rs
+++ b/library/alloc/src/slice.rs
@@ -8,9 +8,6 @@
 //! A few functions are provided to create a slice from a value reference
 //! or from a raw pointer.
 #![stable(feature = "rust1", since = "1.0.0")]
-// Many of the usings in this module are only used in the test configuration.
-// It's cleaner to just turn off the unused_imports warning than to fix them.
-#![cfg_attr(test, allow(unused_imports, dead_code))]
 
 use core::borrow::{Borrow, BorrowMut};
 #[cfg(not(no_global_oom_handling))]
@@ -63,16 +60,6 @@ pub use core::slice::{range, try_range};
 ////////////////////////////////////////////////////////////////////////////////
 // Basic slice extension methods
 ////////////////////////////////////////////////////////////////////////////////
-
-// HACK(japaric) needed for the implementation of `vec!` macro during testing
-// N.B., see the `hack` module in this file for more details.
-#[cfg(test)]
-pub use hack::into_vec;
-// HACK(japaric) needed for the implementation of `Vec::clone` during testing
-// N.B., see the `hack` module in this file for more details.
-#[cfg(test)]
-pub use hack::to_vec;
-
 use crate::alloc::Allocator;
 #[cfg(not(no_global_oom_handling))]
 use crate::alloc::Global;
@@ -81,98 +68,6 @@ use crate::borrow::ToOwned;
 use crate::boxed::Box;
 use crate::vec::Vec;
 
-// HACK(japaric): With cfg(test) `impl [T]` is not available, these three
-// functions are actually methods that are in `impl [T]` but not in
-// `core::slice::SliceExt` - we need to supply these functions for the
-// `test_permutations` test
-#[allow(unreachable_pub)] // cfg(test) pub above
-pub(crate) mod hack {
-    use core::alloc::Allocator;
-
-    use crate::boxed::Box;
-    use crate::vec::Vec;
-
-    // We shouldn't add inline attribute to this since this is used in
-    // `vec!` macro mostly and causes perf regression. See #71204 for
-    // discussion and perf results.
-    #[allow(missing_docs)]
-    pub fn into_vec<T, A: Allocator>(b: Box<[T], A>) -> Vec<T, A> {
-        unsafe {
-            let len = b.len();
-            let (b, alloc) = Box::into_raw_with_allocator(b);
-            Vec::from_raw_parts_in(b as *mut T, len, len, alloc)
-        }
-    }
-
-    #[cfg(not(no_global_oom_handling))]
-    #[allow(missing_docs)]
-    #[inline]
-    pub fn to_vec<T: ConvertVec, A: Allocator>(s: &[T], alloc: A) -> Vec<T, A> {
-        T::to_vec(s, alloc)
-    }
-
-    #[cfg(not(no_global_oom_handling))]
-    pub trait ConvertVec {
-        fn to_vec<A: Allocator>(s: &[Self], alloc: A) -> Vec<Self, A>
-        where
-            Self: Sized;
-    }
-
-    #[cfg(not(no_global_oom_handling))]
-    impl<T: Clone> ConvertVec for T {
-        #[inline]
-        default fn to_vec<A: Allocator>(s: &[Self], alloc: A) -> Vec<Self, A> {
-            struct DropGuard<'a, T, A: Allocator> {
-                vec: &'a mut Vec<T, A>,
-                num_init: usize,
-            }
-            impl<'a, T, A: Allocator> Drop for DropGuard<'a, T, A> {
-                #[inline]
-                fn drop(&mut self) {
-                    // SAFETY:
-                    // items were marked initialized in the loop below
-                    unsafe {
-                        self.vec.set_len(self.num_init);
-                    }
-                }
-            }
-            let mut vec = Vec::with_capacity_in(s.len(), alloc);
-            let mut guard = DropGuard { vec: &mut vec, num_init: 0 };
-            let slots = guard.vec.spare_capacity_mut();
-            // .take(slots.len()) is necessary for LLVM to remove bounds checks
-            // and has better codegen than zip.
-            for (i, b) in s.iter().enumerate().take(slots.len()) {
-                guard.num_init = i;
-                slots[i].write(b.clone());
-            }
-            core::mem::forget(guard);
-            // SAFETY:
-            // the vec was allocated and initialized above to at least this length.
-            unsafe {
-                vec.set_len(s.len());
-            }
-            vec
-        }
-    }
-
-    #[cfg(not(no_global_oom_handling))]
-    impl<T: Copy> ConvertVec for T {
-        #[inline]
-        fn to_vec<A: Allocator>(s: &[Self], alloc: A) -> Vec<Self, A> {
-            let mut v = Vec::with_capacity_in(s.len(), alloc);
-            // SAFETY:
-            // allocated above with the capacity of `s`, and initialize to `s.len()` in
-            // ptr::copy_to_non_overlapping below.
-            unsafe {
-                s.as_ptr().copy_to_nonoverlapping(v.as_mut_ptr(), s.len());
-                v.set_len(s.len());
-            }
-            v
-        }
-    }
-}
-
-#[cfg(not(test))]
 impl<T> [T] {
     /// Sorts the slice, preserving initial order of equal elements.
     ///
@@ -501,8 +396,64 @@ impl<T> [T] {
     where
         T: Clone,
     {
-        // N.B., see the `hack` module in this file for more details.
-        hack::to_vec(self, alloc)
+        return T::to_vec(self, alloc);
+
+        trait ConvertVec {
+            fn to_vec<A: Allocator>(s: &[Self], alloc: A) -> Vec<Self, A>
+            where
+                Self: Sized;
+        }
+
+        impl<T: Clone> ConvertVec for T {
+            #[inline]
+            default fn to_vec<A: Allocator>(s: &[Self], alloc: A) -> Vec<Self, A> {
+                struct DropGuard<'a, T, A: Allocator> {
+                    vec: &'a mut Vec<T, A>,
+                    num_init: usize,
+                }
+                impl<'a, T, A: Allocator> Drop for DropGuard<'a, T, A> {
+                    #[inline]
+                    fn drop(&mut self) {
+                        // SAFETY:
+                        // items were marked initialized in the loop below
+                        unsafe {
+                            self.vec.set_len(self.num_init);
+                        }
+                    }
+                }
+                let mut vec = Vec::with_capacity_in(s.len(), alloc);
+                let mut guard = DropGuard { vec: &mut vec, num_init: 0 };
+                let slots = guard.vec.spare_capacity_mut();
+                // .take(slots.len()) is necessary for LLVM to remove bounds checks
+                // and has better codegen than zip.
+                for (i, b) in s.iter().enumerate().take(slots.len()) {
+                    guard.num_init = i;
+                    slots[i].write(b.clone());
+                }
+                core::mem::forget(guard);
+                // SAFETY:
+                // the vec was allocated and initialized above to at least this length.
+                unsafe {
+                    vec.set_len(s.len());
+                }
+                vec
+            }
+        }
+
+        impl<T: Copy> ConvertVec for T {
+            #[inline]
+            fn to_vec<A: Allocator>(s: &[Self], alloc: A) -> Vec<Self, A> {
+                let mut v = Vec::with_capacity_in(s.len(), alloc);
+                // SAFETY:
+                // allocated above with the capacity of `s`, and initialize to `s.len()` in
+                // ptr::copy_to_non_overlapping below.
+                unsafe {
+                    s.as_ptr().copy_to_nonoverlapping(v.as_mut_ptr(), s.len());
+                    v.set_len(s.len());
+                }
+                v
+            }
+        }
     }
 
     /// Converts `self` into a vector without clones or allocation.
@@ -522,10 +473,13 @@ impl<T> [T] {
     #[rustc_allow_incoherent_impl]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "slice_into_vec")]
+    #[rustc_diagnostic_item = "slice_into_vec"]
     pub fn into_vec<A: Allocator>(self: Box<Self, A>) -> Vec<T, A> {
-        // N.B., see the `hack` module in this file for more details.
-        hack::into_vec(self)
+        unsafe {
+            let len = self.len();
+            let (b, alloc) = Box::into_raw_with_allocator(self);
+            Vec::from_raw_parts_in(b as *mut T, len, len, alloc)
+        }
     }
 
     /// Creates a vector by copying a slice `n` times.
@@ -666,7 +620,6 @@ impl<T> [T] {
     }
 }
 
-#[cfg(not(test))]
 impl [u8] {
     /// Returns a vector containing a copy of this slice where each byte
     /// is mapped to its ASCII upper case equivalent.
@@ -883,14 +836,9 @@ impl<T: Copy, A: Allocator> SpecCloneIntoVec<T, A> for [T] {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: Clone> ToOwned for [T] {
     type Owned = Vec<T>;
-    #[cfg(not(test))]
-    fn to_owned(&self) -> Vec<T> {
-        self.to_vec()
-    }
 
-    #[cfg(test)]
     fn to_owned(&self) -> Vec<T> {
-        hack::to_vec(self, Global)
+        self.to_vec()
     }
 
     fn clone_into(&self, target: &mut Vec<T>) {
diff --git a/library/alloc/src/str.rs b/library/alloc/src/str.rs
index 6fee8d3fe33..0664f2c3cf2 100644
--- a/library/alloc/src/str.rs
+++ b/library/alloc/src/str.rs
@@ -219,7 +219,6 @@ impl ToOwned for str {
 }
 
 /// Methods for string slices.
-#[cfg(not(test))]
 impl str {
     /// Converts a `Box<str>` into a `Box<[u8]>` without copying or allocating.
     ///
@@ -631,7 +630,6 @@ pub unsafe fn from_boxed_utf8_unchecked(v: Box<[u8]>) -> Box<str> {
 #[unstable(feature = "str_internals", issue = "none")]
 #[doc(hidden)]
 #[inline]
-#[cfg(not(test))]
 #[cfg(not(no_global_oom_handling))]
 pub fn convert_while_ascii(s: &str, convert: fn(&u8) -> u8) -> (String, &str) {
     // Process the input in chunks of 16 bytes to enable auto-vectorization.
@@ -704,7 +702,6 @@ pub fn convert_while_ascii(s: &str, convert: fn(&u8) -> u8) -> (String, &str) {
     }
 }
 #[inline]
-#[cfg(not(test))]
 #[cfg(not(no_global_oom_handling))]
 #[allow(dead_code)]
 /// Faster implementation of string replacement for ASCII to ASCII cases.
diff --git a/library/alloc/src/string.rs b/library/alloc/src/string.rs
index 2c034786549..2ba797ab2ad 100644
--- a/library/alloc/src/string.rs
+++ b/library/alloc/src/string.rs
@@ -356,7 +356,7 @@ use crate::vec::{self, Vec};
 /// [`as_str()`]: String::as_str
 #[derive(PartialEq, PartialOrd, Eq, Ord)]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), lang = "String")]
+#[lang = "String"]
 pub struct String {
     vec: Vec<u8>,
 }
@@ -438,7 +438,7 @@ impl String {
     /// ```
     #[inline]
     #[rustc_const_stable(feature = "const_string_new", since = "1.39.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "string_new")]
+    #[rustc_diagnostic_item = "string_new"]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
     pub const fn new() -> String {
@@ -501,17 +501,6 @@ impl String {
         Ok(String { vec: Vec::try_with_capacity(capacity)? })
     }
 
-    // HACK(japaric): with cfg(test) the inherent `[T]::to_vec` method, which is
-    // required for this method definition, is not available. Since we don't
-    // require this method for testing purposes, I'll just stub it
-    // NB see the slice::hack module in slice.rs for more information
-    #[inline]
-    #[cfg(test)]
-    #[allow(missing_docs)]
-    pub fn from_str(_: &str) -> String {
-        panic!("not available with cfg(test)");
-    }
-
     /// Converts a vector of bytes to a `String`.
     ///
     /// A string ([`String`]) is made of bytes ([`u8`]), and a vector of bytes
@@ -570,7 +559,7 @@ impl String {
     /// [`into_bytes`]: String::into_bytes
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "string_from_utf8")]
+    #[rustc_diagnostic_item = "string_from_utf8"]
     pub fn from_utf8(vec: Vec<u8>) -> Result<String, FromUtf8Error> {
         match str::from_utf8(&vec) {
             Ok(..) => Ok(String { vec }),
@@ -1071,7 +1060,7 @@ impl String {
     #[inline]
     #[must_use]
     #[stable(feature = "string_as_str", since = "1.7.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "string_as_str")]
+    #[rustc_diagnostic_item = "string_as_str"]
     #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
     pub const fn as_str(&self) -> &str {
         // SAFETY: String contents are stipulated to be valid UTF-8, invalid contents are an error
@@ -1094,7 +1083,7 @@ impl String {
     #[inline]
     #[must_use]
     #[stable(feature = "string_as_str", since = "1.7.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "string_as_mut_str")]
+    #[rustc_diagnostic_item = "string_as_mut_str"]
     #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
     pub const fn as_mut_str(&mut self) -> &mut str {
         // SAFETY: String contents are stipulated to be valid UTF-8, invalid contents are an error
@@ -1117,7 +1106,7 @@ impl String {
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_confusables("append", "push")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "string_push_str")]
+    #[rustc_diagnostic_item = "string_push_str"]
     pub fn push_str(&mut self, string: &str) {
         self.vec.extend_from_slice(string.as_bytes())
     }
@@ -1755,7 +1744,7 @@ impl String {
     #[cfg(not(no_global_oom_handling))]
     #[inline]
     #[stable(feature = "insert_str", since = "1.16.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "string_insert_str")]
+    #[rustc_diagnostic_item = "string_insert_str"]
     pub fn insert_str(&mut self, idx: usize, string: &str) {
         assert!(self.is_char_boundary(idx));
 
@@ -2724,7 +2713,7 @@ impl FromStr for String {
 /// implementation for free.
 ///
 /// [`Display`]: fmt::Display
-#[cfg_attr(not(test), rustc_diagnostic_item = "ToString")]
+#[rustc_diagnostic_item = "ToString"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait ToString {
     /// Converts the given value to a `String`.
@@ -2739,7 +2728,7 @@ pub trait ToString {
     /// ```
     #[rustc_conversion_suggestion]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "to_string_method")]
+    #[rustc_diagnostic_item = "to_string_method"]
     fn to_string(&self) -> String;
 }
 
@@ -2979,7 +2968,6 @@ impl From<&String> for String {
 }
 
 // note: test pulls in std, which causes errors here
-#[cfg(not(test))]
 #[stable(feature = "string_from_box", since = "1.18.0")]
 impl From<Box<str>> for String {
     /// Converts the given boxed `str` slice to a [`String`].
diff --git a/library/alloc/src/sync.rs b/library/alloc/src/sync.rs
index 21ee59cc538..4999319f618 100644
--- a/library/alloc/src/sync.rs
+++ b/library/alloc/src/sync.rs
@@ -235,7 +235,7 @@ macro_rules! acquire {
 ///
 /// [rc_examples]: crate::rc#examples
 #[doc(search_unbox)]
-#[cfg_attr(not(test), rustc_diagnostic_item = "Arc")]
+#[rustc_diagnostic_item = "Arc"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_insignificant_dtor]
 pub struct Arc<
@@ -312,7 +312,7 @@ impl<T: ?Sized, A: Allocator> Arc<T, A> {
 ///
 /// [`upgrade`]: Weak::upgrade
 #[stable(feature = "arc_weak", since = "1.4.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "ArcWeak")]
+#[rustc_diagnostic_item = "ArcWeak"]
 pub struct Weak<
     T: ?Sized,
     #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global,
diff --git a/library/alloc/src/testing/crash_test.rs b/library/alloc/src/testing/crash_test.rs
deleted file mode 100644
index 8e00e4f41e5..00000000000
--- a/library/alloc/src/testing/crash_test.rs
+++ /dev/null
@@ -1,120 +0,0 @@
-use std::cmp::Ordering;
-use std::sync::atomic::AtomicUsize;
-use std::sync::atomic::Ordering::SeqCst;
-
-use crate::fmt::Debug; // the `Debug` trait is the only thing we use from `crate::fmt`
-
-/// A blueprint for crash test dummy instances that monitor particular events.
-/// Some instances may be configured to panic at some point.
-/// Events are `clone`, `drop` or some anonymous `query`.
-///
-/// Crash test dummies are identified and ordered by an id, so they can be used
-/// as keys in a BTreeMap.
-#[derive(Debug)]
-pub(crate) struct CrashTestDummy {
-    pub id: usize,
-    cloned: AtomicUsize,
-    dropped: AtomicUsize,
-    queried: AtomicUsize,
-}
-
-impl CrashTestDummy {
-    /// Creates a crash test dummy design. The `id` determines order and equality of instances.
-    pub(crate) fn new(id: usize) -> CrashTestDummy {
-        CrashTestDummy {
-            id,
-            cloned: AtomicUsize::new(0),
-            dropped: AtomicUsize::new(0),
-            queried: AtomicUsize::new(0),
-        }
-    }
-
-    /// Creates an instance of a crash test dummy that records what events it experiences
-    /// and optionally panics.
-    pub(crate) fn spawn(&self, panic: Panic) -> Instance<'_> {
-        Instance { origin: self, panic }
-    }
-
-    /// Returns how many times instances of the dummy have been cloned.
-    pub(crate) fn cloned(&self) -> usize {
-        self.cloned.load(SeqCst)
-    }
-
-    /// Returns how many times instances of the dummy have been dropped.
-    pub(crate) fn dropped(&self) -> usize {
-        self.dropped.load(SeqCst)
-    }
-
-    /// Returns how many times instances of the dummy have had their `query` member invoked.
-    pub(crate) fn queried(&self) -> usize {
-        self.queried.load(SeqCst)
-    }
-}
-
-#[derive(Debug)]
-pub(crate) struct Instance<'a> {
-    origin: &'a CrashTestDummy,
-    panic: Panic,
-}
-
-#[derive(Copy, Clone, Debug, PartialEq, Eq)]
-pub(crate) enum Panic {
-    Never,
-    InClone,
-    InDrop,
-    InQuery,
-}
-
-impl Instance<'_> {
-    pub(crate) fn id(&self) -> usize {
-        self.origin.id
-    }
-
-    /// Some anonymous query, the result of which is already given.
-    pub(crate) fn query<R>(&self, result: R) -> R {
-        self.origin.queried.fetch_add(1, SeqCst);
-        if self.panic == Panic::InQuery {
-            panic!("panic in `query`");
-        }
-        result
-    }
-}
-
-impl Clone for Instance<'_> {
-    fn clone(&self) -> Self {
-        self.origin.cloned.fetch_add(1, SeqCst);
-        if self.panic == Panic::InClone {
-            panic!("panic in `clone`");
-        }
-        Self { origin: self.origin, panic: Panic::Never }
-    }
-}
-
-impl Drop for Instance<'_> {
-    fn drop(&mut self) {
-        self.origin.dropped.fetch_add(1, SeqCst);
-        if self.panic == Panic::InDrop {
-            panic!("panic in `drop`");
-        }
-    }
-}
-
-impl PartialOrd for Instance<'_> {
-    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        self.id().partial_cmp(&other.id())
-    }
-}
-
-impl Ord for Instance<'_> {
-    fn cmp(&self, other: &Self) -> Ordering {
-        self.id().cmp(&other.id())
-    }
-}
-
-impl PartialEq for Instance<'_> {
-    fn eq(&self, other: &Self) -> bool {
-        self.id().eq(&other.id())
-    }
-}
-
-impl Eq for Instance<'_> {}
diff --git a/library/alloc/src/testing/mod.rs b/library/alloc/src/testing/mod.rs
deleted file mode 100644
index c8457daf93e..00000000000
--- a/library/alloc/src/testing/mod.rs
+++ /dev/null
@@ -1,3 +0,0 @@
-pub(crate) mod crash_test;
-pub(crate) mod ord_chaos;
-pub(crate) mod rng;
diff --git a/library/alloc/src/testing/ord_chaos.rs b/library/alloc/src/testing/ord_chaos.rs
deleted file mode 100644
index 55e1ae5e3de..00000000000
--- a/library/alloc/src/testing/ord_chaos.rs
+++ /dev/null
@@ -1,81 +0,0 @@
-use std::cell::Cell;
-use std::cmp::Ordering::{self, *};
-use std::ptr;
-
-// Minimal type with an `Ord` implementation violating transitivity.
-#[derive(Debug)]
-pub(crate) enum Cyclic3 {
-    A,
-    B,
-    C,
-}
-use Cyclic3::*;
-
-impl PartialOrd for Cyclic3 {
-    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-impl Ord for Cyclic3 {
-    fn cmp(&self, other: &Self) -> Ordering {
-        match (self, other) {
-            (A, A) | (B, B) | (C, C) => Equal,
-            (A, B) | (B, C) | (C, A) => Less,
-            (A, C) | (B, A) | (C, B) => Greater,
-        }
-    }
-}
-
-impl PartialEq for Cyclic3 {
-    fn eq(&self, other: &Self) -> bool {
-        self.cmp(&other) == Equal
-    }
-}
-
-impl Eq for Cyclic3 {}
-
-// Controls the ordering of values wrapped by `Governed`.
-#[derive(Debug)]
-pub(crate) struct Governor {
-    flipped: Cell<bool>,
-}
-
-impl Governor {
-    pub(crate) fn new() -> Self {
-        Governor { flipped: Cell::new(false) }
-    }
-
-    pub(crate) fn flip(&self) {
-        self.flipped.set(!self.flipped.get());
-    }
-}
-
-// Type with an `Ord` implementation that forms a total order at any moment
-// (assuming that `T` respects total order), but can suddenly be made to invert
-// that total order.
-#[derive(Debug)]
-pub(crate) struct Governed<'a, T>(pub T, pub &'a Governor);
-
-impl<T: Ord> PartialOrd for Governed<'_, T> {
-    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-impl<T: Ord> Ord for Governed<'_, T> {
-    fn cmp(&self, other: &Self) -> Ordering {
-        assert!(ptr::eq(self.1, other.1));
-        let ord = self.0.cmp(&other.0);
-        if self.1.flipped.get() { ord.reverse() } else { ord }
-    }
-}
-
-impl<T: PartialEq> PartialEq for Governed<'_, T> {
-    fn eq(&self, other: &Self) -> bool {
-        assert!(ptr::eq(self.1, other.1));
-        self.0.eq(&other.0)
-    }
-}
-
-impl<T: Eq> Eq for Governed<'_, T> {}
diff --git a/library/alloc/src/testing/rng.rs b/library/alloc/src/testing/rng.rs
deleted file mode 100644
index 77d3348f38a..00000000000
--- a/library/alloc/src/testing/rng.rs
+++ /dev/null
@@ -1,28 +0,0 @@
-/// XorShiftRng
-pub(crate) struct DeterministicRng {
-    count: usize,
-    x: u32,
-    y: u32,
-    z: u32,
-    w: u32,
-}
-
-impl DeterministicRng {
-    pub(crate) fn new() -> Self {
-        DeterministicRng { count: 0, x: 0x193a6754, y: 0xa8a7d469, z: 0x97830e05, w: 0x113ba7bb }
-    }
-
-    /// Guarantees that each returned number is unique.
-    pub(crate) fn next(&mut self) -> u32 {
-        self.count += 1;
-        assert!(self.count <= 70029);
-        let x = self.x;
-        let t = x ^ (x << 11);
-        self.x = self.y;
-        self.y = self.z;
-        self.z = self.w;
-        let w_ = self.w;
-        self.w = w_ ^ (w_ >> 19) ^ (t ^ (t >> 8));
-        self.w
-    }
-}
diff --git a/library/alloc/src/vec/into_iter.rs b/library/alloc/src/vec/into_iter.rs
index 52597e41c1c..3eee988b6c9 100644
--- a/library/alloc/src/vec/into_iter.rs
+++ b/library/alloc/src/vec/into_iter.rs
@@ -472,14 +472,9 @@ where
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "vec_into_iter_clone", since = "1.8.0")]
 impl<T: Clone, A: Allocator + Clone> Clone for IntoIter<T, A> {
-    #[cfg(not(test))]
     fn clone(&self) -> Self {
         self.as_slice().to_vec_in(self.alloc.deref().clone()).into_iter()
     }
-    #[cfg(test)]
-    fn clone(&self) -> Self {
-        crate::slice::to_vec(self.as_slice(), self.alloc.deref().clone()).into_iter()
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/library/alloc/src/vec/mod.rs b/library/alloc/src/vec/mod.rs
index 49878f2b6fa..ce668540598 100644
--- a/library/alloc/src/vec/mod.rs
+++ b/library/alloc/src/vec/mod.rs
@@ -404,7 +404,7 @@ mod spec_extend;
 /// [owned slice]: Box
 /// [`into_boxed_slice`]: Vec::into_boxed_slice
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "Vec")]
+#[rustc_diagnostic_item = "Vec"]
 #[rustc_insignificant_dtor]
 pub struct Vec<T, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global> {
     buf: RawVec<T, A>,
@@ -428,7 +428,7 @@ impl<T> Vec<T> {
     /// ```
     #[inline]
     #[rustc_const_stable(feature = "const_vec_new", since = "1.39.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "vec_new")]
+    #[rustc_diagnostic_item = "vec_new"]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
     pub const fn new() -> Self {
@@ -489,7 +489,7 @@ impl<T> Vec<T> {
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "vec_with_capacity")]
+    #[rustc_diagnostic_item = "vec_with_capacity"]
     #[track_caller]
     pub fn with_capacity(capacity: usize) -> Self {
         Self::with_capacity_in(capacity, Global)
@@ -1279,7 +1279,7 @@ impl<T, A: Allocator> Vec<T, A> {
     #[cfg(not(no_global_oom_handling))]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[track_caller]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "vec_reserve")]
+    #[rustc_diagnostic_item = "vec_reserve"]
     pub fn reserve(&mut self, additional: usize) {
         self.buf.reserve(self.len, additional);
     }
@@ -1568,7 +1568,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// ```
     #[inline]
     #[stable(feature = "vec_as_slice", since = "1.7.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "vec_as_slice")]
+    #[rustc_diagnostic_item = "vec_as_slice"]
     #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
     pub const fn as_slice(&self) -> &[T] {
         // SAFETY: `slice::from_raw_parts` requires pointee is a contiguous, aligned buffer of size
@@ -1600,7 +1600,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// ```
     #[inline]
     #[stable(feature = "vec_as_slice", since = "1.7.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "vec_as_mut_slice")]
+    #[rustc_diagnostic_item = "vec_as_mut_slice"]
     #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
     pub const fn as_mut_slice(&mut self) -> &mut [T] {
         // SAFETY: `slice::from_raw_parts_mut` requires pointee is a contiguous, aligned buffer of
@@ -2511,7 +2511,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// Takes *O*(1) time.
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "vec_pop")]
+    #[rustc_diagnostic_item = "vec_pop"]
     pub fn pop(&mut self) -> Option<T> {
         if self.len == 0 {
             None
@@ -2712,7 +2712,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// assert!(!v.is_empty());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "vec_is_empty")]
+    #[rustc_diagnostic_item = "vec_is_empty"]
     #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
     pub const fn is_empty(&self) -> bool {
         self.len() == 0
@@ -3193,7 +3193,7 @@ impl<T: PartialEq, A: Allocator> Vec<T, A> {
 #[doc(hidden)]
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "vec_from_elem")]
+#[rustc_diagnostic_item = "vec_from_elem"]
 #[track_caller]
 pub fn from_elem<T: Clone>(elem: T, n: usize) -> Vec<T> {
     <T as SpecFromElem>::from_elem(elem, n, Global)
@@ -3293,23 +3293,12 @@ unsafe impl<T, A: Allocator> ops::DerefPure for Vec<T, A> {}
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: Clone, A: Allocator + Clone> Clone for Vec<T, A> {
-    #[cfg(not(test))]
     #[track_caller]
     fn clone(&self) -> Self {
         let alloc = self.allocator().clone();
         <[T]>::to_vec_in(&**self, alloc)
     }
 
-    // HACK(japaric): with cfg(test) the inherent `[T]::to_vec` method, which is
-    // required for this method definition, is not available. Instead use the
-    // `slice::to_vec` function which is only available with cfg(test)
-    // NB see the slice::hack module in slice.rs for more information
-    #[cfg(test)]
-    fn clone(&self) -> Self {
-        let alloc = self.allocator().clone();
-        crate::slice::to_vec(&**self, alloc)
-    }
-
     /// Overwrites the contents of `self` with a clone of the contents of `source`.
     ///
     /// This method is preferred over simply assigning `source.clone()` to `self`,
@@ -3854,15 +3843,10 @@ impl<T: Clone> From<&[T]> for Vec<T> {
     /// ```
     /// assert_eq!(Vec::from(&[1, 2, 3][..]), vec![1, 2, 3]);
     /// ```
-    #[cfg(not(test))]
     #[track_caller]
     fn from(s: &[T]) -> Vec<T> {
         s.to_vec()
     }
-    #[cfg(test)]
-    fn from(s: &[T]) -> Vec<T> {
-        crate::slice::to_vec(s, Global)
-    }
 }
 
 #[cfg(not(no_global_oom_handling))]
@@ -3875,15 +3859,10 @@ impl<T: Clone> From<&mut [T]> for Vec<T> {
     /// ```
     /// assert_eq!(Vec::from(&mut [1, 2, 3][..]), vec![1, 2, 3]);
     /// ```
-    #[cfg(not(test))]
     #[track_caller]
     fn from(s: &mut [T]) -> Vec<T> {
         s.to_vec()
     }
-    #[cfg(test)]
-    fn from(s: &mut [T]) -> Vec<T> {
-        crate::slice::to_vec(s, Global)
-    }
 }
 
 #[cfg(not(no_global_oom_handling))]
@@ -3928,16 +3907,10 @@ impl<T, const N: usize> From<[T; N]> for Vec<T> {
     /// ```
     /// assert_eq!(Vec::from([1, 2, 3]), vec![1, 2, 3]);
     /// ```
-    #[cfg(not(test))]
     #[track_caller]
     fn from(s: [T; N]) -> Vec<T> {
         <[T]>::into_vec(Box::new(s))
     }
-
-    #[cfg(test)]
-    fn from(s: [T; N]) -> Vec<T> {
-        crate::slice::into_vec(Box::new(s))
-    }
 }
 
 #[stable(feature = "vec_from_cow_slice", since = "1.14.0")]
@@ -3966,7 +3939,6 @@ where
 }
 
 // note: test pulls in std, which causes errors here
-#[cfg(not(test))]
 #[stable(feature = "vec_from_box", since = "1.18.0")]
 impl<T, A: Allocator> From<Box<[T], A>> for Vec<T, A> {
     /// Converts a boxed slice into a vector by transferring ownership of
@@ -3985,7 +3957,6 @@ impl<T, A: Allocator> From<Box<[T], A>> for Vec<T, A> {
 
 // note: test pulls in std, which causes errors here
 #[cfg(not(no_global_oom_handling))]
-#[cfg(not(test))]
 #[stable(feature = "box_from_vec", since = "1.20.0")]
 impl<T, A: Allocator> From<Vec<T, A>> for Box<[T], A> {
     /// Converts a vector into a boxed slice.