Fix hashmap tests

lib/stdlib/test/ets_SUITE.erl

@@ -1956,7 +1956,7 @@ t_select_hashmap_term_copy_bug(_Config) ->
             _ -> {250, 32}
         end,
 
-    LM = maps:from_list([{V,1} || V <- lists:seq(1,LargeMapSize)]),
+    LM = maps:from_keys(lists:seq(1,LargeMapSize), 1),
 
     lists:foreach(
       fun(Key) ->
@@ -1968,21 +1968,23 @@ t_select_hashmap_term_copy_bug(_Config) ->
               V = [LM#{ Key => Dollar1 }]
       end, maps:keys(LM)),
 
-    LMWithDollar = LM#{ '$1' => a },
+    %% Create a hashmap with enough keys before and after the '$1' for it to
+    %% remain a hashmap when we remove those keys.
+    LMWithDollar = make_lm_with_dollar(LM#{ '$1' => a }, LargeMapSize, FlatmapSize),
 
     %% Test that hashmap with '$1' in first position works
     %% We rely on that fact that maps:keys return the keys
     %% in iteration order.
     lists:foldl(
       fun
-          (Key, M = #{ '$1' := _ }) ->
+          (Key, M = #{ '$1' := A }) when map_size(M) > FlatmapSize ->
 
               V = ets:select(T, [{{'$1'},[], [M]}]),
               erlang:garbage_collect(),
               V = ets:select(T, [{{'$1'},[], [M]}]),
               erlang:garbage_collect(),
 
-              V = [(maps:remove('$1',M))#{ Dollar1 => a }],
+              V = [(maps:remove('$1',M))#{ Dollar1 => A }],
 
               maps:remove(Key, M);
           (_, M) when map_size(M) > FlatmapSize ->
@@ -1994,14 +1996,14 @@ t_select_hashmap_term_copy_bug(_Config) ->
     %% in iteration order.
     lists:foldl(
       fun
-          (Key, M = #{ '$1' := _ }) ->
+          (Key, M = #{ '$1' := A }) ->
 
               V = ets:select(T, [{{'$1'},[], [M]}]),
               erlang:garbage_collect(),
               V = ets:select(T, [{{'$1'},[], [M]}]),
               erlang:garbage_collect(),
 
-              V = [(maps:remove('$1',M))#{ Dollar1 => a }],
+              V = [(maps:remove('$1',M))#{ Dollar1 => A }],
 
               maps:remove(Key, M);
           (_, M) when map_size(M) > FlatmapSize ->
@@ -2027,6 +2029,20 @@ t_select_hashmap_term_copy_bug(_Config) ->
     ets:delete(T),
     ok.
 
+%% Create a hashmap that always has FlatmapSize keys before and after '$1'.
+%% Since the atom index of '$1' is used as hash, we cannot know before the
+%% code is run where exactly it will be placed, so in the rare cases when
+%% there isn't enough keys in the map, we insert more until there are enough.
+make_lm_with_dollar(Map, LargeMapSize, FlatmapSize) ->
+    {KeysBefore, KeysAfter} = lists:splitwith(fun erlang:is_integer/1, maps:keys(Map)),
+    if length(KeysBefore) =< FlatmapSize;
+       length(KeysAfter) - 1 =< FlatmapSize ->
+            NewMap = maps:from_keys(lists:seq(LargeMapSize, LargeMapSize*2), 1),
+            make_lm_with_dollar(maps:merge(Map, NewMap), LargeMapSize*2, FlatmapSize);
+       true ->
+            Map
+    end.
+
 %% Test that partly bound keys gives faster matches.
 partly_bound(Config) when is_list(Config) ->
     case os:type() of