Update tests to use pluggable storage engine API

COUCHDB-3287
diff --git a/test/couch_replicator_compact_tests.erl b/test/couch_replicator_compact_tests.erl
index 5731ff4..3ac35a1 100644
--- a/test/couch_replicator_compact_tests.erl
+++ b/test/couch_replicator_compact_tests.erl
@@ -221,7 +221,7 @@
     {timeout, 35, ?_test(begin
         {ok, SourceDb} = couch_db:open_int(Source, []),
         {ok, TargetDb} = couch_db:open_int(Target, []),
-        Fun = fun(FullDocInfo, _, Acc) ->
+        Fun = fun(FullDocInfo, Acc) ->
             {ok, Doc} = couch_db:open_doc(SourceDb, FullDocInfo),
             {Props} = DocJson = couch_doc:to_json_obj(Doc, [attachments]),
             DocId = couch_util:get_value(<<"_id">>, Props),
@@ -240,7 +240,7 @@
             ?assertEqual(DocJson, DocTargetJson),
             {ok, Acc}
         end,
-        {ok, _, _} = couch_db:enum_docs(SourceDb, Fun, [], []),
+        {ok, _} = couch_db:fold_docs(SourceDb, Fun, [], []),
         ok = couch_db:close(SourceDb),
         ok = couch_db:close(TargetDb)
     end)}.
diff --git a/test/couch_replicator_filtered_tests.erl b/test/couch_replicator_filtered_tests.erl
index 03cf44c..d34e9f0 100644
--- a/test/couch_replicator_filtered_tests.erl
+++ b/test/couch_replicator_filtered_tests.erl
@@ -169,7 +169,7 @@
     {ok, SourceDb} = couch_db:open_int(Source, []),
     {ok, TargetDb} = couch_db:open_int(Target, []),
     {ok, TargetDbInfo} = couch_db:get_db_info(TargetDb),
-    Fun = fun(FullDocInfo, _, Acc) ->
+    Fun = fun(FullDocInfo, Acc) ->
         {ok, DocId, SourceDoc} = read_doc(SourceDb, FullDocInfo),
         TargetReply = read_doc(TargetDb, DocId),
         case FilterFun(DocId, SourceDoc) of
@@ -181,7 +181,7 @@
                 {ok, [ValidReply|Acc]}
         end
     end,
-    {ok, _, AllReplies} = couch_db:enum_docs(SourceDb, Fun, [], []),
+    {ok, AllReplies} = couch_db:fold_docs(SourceDb, Fun, [], []),
     ok = couch_db:close(SourceDb),
     ok = couch_db:close(TargetDb),
     {ok, TargetDbInfo, AllReplies}.
diff --git a/test/couch_replicator_missing_stubs_tests.erl b/test/couch_replicator_missing_stubs_tests.erl
index e8ccd64..f8d231d 100644
--- a/test/couch_replicator_missing_stubs_tests.erl
+++ b/test/couch_replicator_missing_stubs_tests.erl
@@ -131,9 +131,9 @@
 
 update_db_docs(DbName, Times) ->
     {ok, Db} = couch_db:open_int(DbName, []),
-    {ok, _, _} = couch_db:enum_docs(
+    {ok, _} = couch_db:fold_docs(
         Db,
-        fun(FDI, _, Acc) -> db_fold_fun(FDI, Acc) end,
+        fun(FDI, Acc) -> db_fold_fun(FDI, Acc) end,
         {DbName, Times},
         []),
     ok = couch_db:close(Db).
diff --git a/test/couch_replicator_selector_tests.erl b/test/couch_replicator_selector_tests.erl
index 98c6099..a7f4c5d 100644
--- a/test/couch_replicator_selector_tests.erl
+++ b/test/couch_replicator_selector_tests.erl
@@ -65,7 +65,7 @@
     {ok, SourceDb} = couch_db:open_int(Source, []),
     {ok, TargetDb} = couch_db:open_int(Target, []),
     {ok, TargetDbInfo} = couch_db:get_db_info(TargetDb),
-    Fun = fun(FullDocInfo, _, Acc) ->
+    Fun = fun(FullDocInfo, Acc) ->
         {ok, DocId, SourceDoc} = read_doc(SourceDb, FullDocInfo),
         TargetReply = read_doc(TargetDb, DocId),
         case FilterFun(DocId, SourceDoc) of
@@ -77,7 +77,7 @@
                 {ok, [ValidReply|Acc]}
         end
     end,
-    {ok, _, AllReplies} = couch_db:enum_docs(SourceDb, Fun, [], []),
+    {ok, AllReplies} = couch_db:fold_docs(SourceDb, Fun, [], []),
     ok = couch_db:close(SourceDb),
     ok = couch_db:close(TargetDb),
     {ok, TargetDbInfo, AllReplies}.
diff --git a/test/couch_replicator_test_helper.erl b/test/couch_replicator_test_helper.erl
index 398b27b..ae27745 100644
--- a/test/couch_replicator_test_helper.erl
+++ b/test/couch_replicator_test_helper.erl
@@ -14,7 +14,7 @@
     {ok, SourceDb} = couch_db:open_int(Source, []),
     {ok, TargetDb} = couch_db:open_int(Target, []),
 
-    Fun = fun(FullDocInfo, _, Acc) ->
+    Fun = fun(FullDocInfo, Acc) ->
         {ok, DocSource} = couch_db:open_doc(SourceDb, FullDocInfo),
         Id = DocSource#doc.id,
         case lists:member(Id, ExceptIds) of
@@ -27,7 +27,7 @@
         {ok, Acc}
     end,
 
-    {ok, _, _} = couch_db:enum_docs(SourceDb, Fun, [], []),
+    {ok, _} = couch_db:fold_docs(SourceDb, Fun, [], []),
     ok = couch_db:close(SourceDb),
     ok = couch_db:close(TargetDb).
 
diff --git a/test/couch_replicator_use_checkpoints_tests.erl b/test/couch_replicator_use_checkpoints_tests.erl
index e04488e..9dea8af 100644
--- a/test/couch_replicator_use_checkpoints_tests.erl
+++ b/test/couch_replicator_use_checkpoints_tests.erl
@@ -144,7 +144,7 @@
 compare_dbs(Source, Target) ->
     {ok, SourceDb} = couch_db:open_int(Source, []),
     {ok, TargetDb} = couch_db:open_int(Target, []),
-    Fun = fun(FullDocInfo, _, Acc) ->
+    Fun = fun(FullDocInfo, Acc) ->
         {ok, Doc} = couch_db:open_doc(SourceDb, FullDocInfo),
         {Props} = DocJson = couch_doc:to_json_obj(Doc, [attachments]),
         DocId = couch_util:get_value(<<"_id">>, Props),
@@ -163,7 +163,7 @@
         ?assertEqual(DocJson, DocTargetJson),
         {ok, Acc}
     end,
-    {ok, _, _} = couch_db:enum_docs(SourceDb, Fun, [], []),
+    {ok, _} = couch_db:fold_docs(SourceDb, Fun, [], []),
     ok = couch_db:close(SourceDb),
     ok = couch_db:close(TargetDb).