Add test for flatten1

.github/workflows/ci.yml

@@ -31,7 +31,7 @@ jobs:
       run: rebar3 proper -c
 
     - name: Coverage
-      run: rebar3 cover --verbose --min_coverage 80
+      run: rebar3 cover --verbose --min_coverage 85
 
     - name: Run Xref
       run: rebar3 xref

src/iterator.erl

@@ -234,6 +234,9 @@ yield_flatmap({Fun, [Item | Tail], InnerIter}) ->
     {Item, {Fun, Tail, InnerIter}}.
 
 %% @doc Converts iterator that yields lists to flat list (non-recursive)
+%%
+%% Do not confuse with `append/1'. This function takes SINGLE iterator that yields
+%% lists and returns list elements one-by-one.
 -spec flatten1(iterator([Type])) -> iterator(Type).
 flatten1(InnerIterator) ->
     flatmap(fun(V) -> V end, InnerIterator).

test/prop_vs_lists.erl

@@ -9,6 +9,7 @@
     prop_map/0,
     prop_mapfoldl/0,
     prop_flatmap/0,
+    prop_flatten1/0,
     prop_filter/0,
     prop_filtermap/0,
     prop_dropwhile/0,
@@ -113,6 +114,21 @@ prop_flatmap() ->
         end
     ).
 
+prop_flatten1() ->
+    Gen = proper_types:list(proper_types:list()),
+    ?FORALL(
+        ListOfLists,
+        Gen,
+        begin
+            Iterator = iterator:from_list(ListOfLists),
+            ?assertEqual(
+                lists:append(ListOfLists),
+                iterator:to_list(iterator:flatten1(Iterator))
+            ),
+            true
+        end
+    ).
+
 prop_filter() ->
     Gen = proper_types:list(proper_types:integer()),
     ?FORALL(