test(ds): Add new helper functions

- Improve message comparison
- Add set operations

apps/emqx/test/emqx_cth_suite.erl

@@ -64,6 +64,7 @@
 
 -export([work_dir/1]).
 -export([work_dir/2]).
+-export([clean_work_dir/1]).
 
 -export([load_apps/1]).
 -export([start_apps/2]).
@@ -432,6 +433,16 @@ work_dir(TCName, CTConfig) ->
     WorkDir = work_dir(CTConfig),
     filename:join(WorkDir, TCName).
 
+%% @doc Delete contents of the workdir.
+clean_work_dir(WorkDir) ->
+    ct:pal("Cleaning workdir ~p", [WorkDir]),
+    case re:run(WorkDir, "./_build/test/logs/") of
+        {match, _} ->
+            file:del_dir_r(WorkDir);
+        nomatch ->
+            error({unsafe_workdir, WorkDir})
+    end.
+
 %%
 
 start_ekka() ->

apps/emqx_durable_storage/test/emqx_ds_test_helpers.erl

@@ -148,8 +148,7 @@ do_ds_topic_generation_stream(DB, Node, Shard, It0) ->
             ?ON(
                 Node,
                 begin
-                    Now = emqx_ds_replication_layer:current_timestamp(DB, Shard),
-                    emqx_ds_storage_layer:next(Shard, It0, 1, Now)
+                    emqx_ds_storage_layer:next(Shard, It0, 1, _Now = 1 bsl 63)
                 end
             )
         of
@@ -233,15 +232,60 @@ transitions(Node, DB) ->
         end
     ).
 
-%% Stream comparison
+%% Message comparison
+
+%% Try to eliminate any ambiguity in the message representation.
+message_canonical_form(Msg0 = #message{}) ->
+    message_canonical_form(emqx_message:to_map(Msg0));
+message_canonical_form(#{flags := Flags0, headers := Headers0, payload := Payload0} = Msg) ->
+    %% Remove flags that are false:
+    Flags = maps:filter(
+        fun(_Key, Val) -> Val end,
+        Flags0
+    ),
+    Msg#{flags := Flags, payload := iolist_to_binary(Payload0)}.
+
+sublist(L) ->
+    PrintMax = 20,
+    case length(L) of
+        0 ->
+            [];
+        N when N > PrintMax ->
+            lists:sublist(L, 1, PrintMax) ++ ['...', N - PrintMax, 'more'];
+        _ ->
+            L
+    end.
+
+message_set(L) ->
+    ordsets:from_list([message_canonical_form(I) || I <- L]).
+
+message_set_subtract(A, B) ->
+    ordsets:subtract(message_set(A), message_set(B)).
+
+assert_same_set(Expected, Got) ->
+    assert_same_set(Expected, Got, #{}).
+
+assert_same_set(Expected, Got, Comment) ->
+    SE = message_set(Expected),
+    SG = message_set(Got),
+    case {ordsets:subtract(SE, SG), ordsets:subtract(SG, SE)} of
+        {[], []} ->
+            ok;
+        {Missing, Unexpected} ->
+            error(Comment#{
+                matching => sublist(ordsets:intersection(SE, SG)),
+                missing => sublist(Missing),
+                unexpected => sublist(Unexpected)
+            })
+    end.
 
 message_eq(Fields, {_Key, Msg1 = #message{}}, Msg2) ->
     message_eq(Fields, Msg1, Msg2);
 message_eq(Fields, Msg1, {_Key, Msg2 = #message{}}) ->
     message_eq(Fields, Msg1, Msg2);
 message_eq(Fields, Msg1 = #message{}, Msg2 = #message{}) ->
-    maps:with(Fields, emqx_message:to_map(Msg1)) =:=
-        maps:with(Fields, emqx_message:to_map(Msg2)).
+    maps:with(Fields, message_canonical_form(Msg1)) =:=
+        maps:with(Fields, message_canonical_form(Msg2)).
 
 %% Consuming streams and iterators
 
@@ -304,6 +348,7 @@ ds_topic_stream(DB, ClientId, TopicBin, Node) ->
                 {DBShard, emqx_ds_storage_layer:get_streams(DBShard, Topic, 0)}
             end
         ),
+    ct:pal("Streams for ~p, ~p @ ~p:~n    ~p", [ClientId, TopicBin, Node, DSStreams]),
     %% Sort streams by their rank Y, and chain them together:
     emqx_utils_stream:chain([
         ds_topic_generation_stream(DB, Node, ShardId, Topic, S)