This patch fixes the tests if the allocator-api2 feature is disabled.

Index: hashbrown/src/map.rs
===================================================================
--- hashbrown.orig/src/map.rs
+++ hashbrown/src/map.rs
@@ -4759,6 +4759,7 @@ mod test_map {
     use super::Entry::{Occupied, Vacant};
     use super::EntryRef;
     use super::HashMap;
+    #[cfg(feature="allocator-api2")]
     use crate::raw::{AllocError, Allocator, Global};
     use alloc::string::{String, ToString};
     use alloc::sync::Arc;
@@ -6206,6 +6207,7 @@ mod test_map {
         }
     }
 
+    #[cfg(feature="allocator-api2")]
     unsafe impl Allocator for MyAlloc {
         fn allocate(&self, layout: Layout) -> std::result::Result<NonNull<[u8]>, AllocError> {
             let g = Global;
@@ -6219,6 +6221,7 @@ mod test_map {
     }
 
     #[test]
+    #[cfg(all(feature="allocator-api2", feature="ahash"))]
     fn test_hashmap_into_iter_bug() {
         let dropped: Arc<AtomicI8> = Arc::new(AtomicI8::new(1));
 
@@ -6289,6 +6292,7 @@ mod test_map {
     ///
     /// This function does not panic, but returns an error as a `String`
     /// to distinguish between a test panic and an error in the input data.
+    #[cfg(all(feature="allocator-api2", feature="ahash"))]
     fn get_test_map<I, T, A>(
         iter: I,
         mut fun: impl FnMut(u64) -> T,
@@ -6382,6 +6386,7 @@ mod test_map {
 
     #[test]
     #[should_panic = "panic in clone"]
+    #[cfg(all(feature="allocator-api2", feature="ahash"))]
     fn test_clone_memory_leaks_and_double_drop_one() {
         let dropped: Arc<AtomicI8> = Arc::new(AtomicI8::new(2));
 
@@ -6408,6 +6413,7 @@ mod test_map {
 
     #[test]
     #[should_panic = "panic in drop"]
+    #[cfg(all(feature="allocator-api2", feature="ahash"))]
     fn test_clone_memory_leaks_and_double_drop_two() {
         let dropped: Arc<AtomicI8> = Arc::new(AtomicI8::new(2));
 
@@ -6442,6 +6448,7 @@ mod test_map {
     /// We check that we have a working table if the clone operation from another
     /// thread ended in a panic (when buckets of maps are equal to each other).
     #[test]
+    #[cfg(all(feature="allocator-api2", feature="ahash"))]
     fn test_catch_panic_clone_from_when_len_is_equal() {
         use std::thread;
 
@@ -6507,6 +6514,7 @@ mod test_map {
     /// We check that we have a working table if the clone operation from another
     /// thread ended in a panic (when buckets of maps are not equal to each other).
     #[test]
+    #[cfg(all(feature="allocator-api2", feature="ahash"))]
     fn test_catch_panic_clone_from_when_len_is_not_equal() {
         use std::thread;
 
Index: hashbrown/src/raw/mod.rs
===================================================================
--- hashbrown.orig/src/raw/mod.rs
+++ hashbrown/src/raw/mod.rs
@@ -13,6 +13,7 @@ use core::{hint, ptr};
 
 mod alloc;
 #[cfg(test)]
+#[cfg(any(feature = "nightly", feature = "allocator-api2"))]
 pub(crate) use self::alloc::AllocError;
 pub(crate) use self::alloc::{do_alloc, Allocator, Global};
 
@@ -4290,6 +4291,7 @@ mod test_map {
     /// CHECKING THAT WE DON'T TRY TO DROP DATA IF THE `ITEMS`
     /// ARE ZERO, EVEN IF WE HAVE `FULL` CONTROL BYTES.
     #[test]
+    #[cfg(feature="allocator-api2")]
     fn test_catch_panic_clone_from() {
         use super::{AllocError, Allocator, Global};
         use ::alloc::sync::Arc;
@@ -4313,6 +4315,7 @@ mod test_map {
             }
         }
 
+        #[cfg(feature="allocator-api2")]
         unsafe impl Allocator for MyAlloc {
             fn allocate(&self, layout: Layout) -> std::result::Result<NonNull<[u8]>, AllocError> {
                 let g = Global;
Index: hashbrown/src/raw/alloc.rs
===================================================================
--- hashbrown.orig/src/raw/alloc.rs
+++ hashbrown/src/raw/alloc.rs
@@ -1,4 +1,5 @@
 #[cfg(test)]
+#[cfg(any(feature = "nightly", feature = "allocator-api2"))]
 pub(crate) use self::inner::AllocError;
 pub(crate) use self::inner::{do_alloc, Allocator, Global};