mongomock · hazard595 · Apr 16, 2025
diff --git a/README.rst b/README.rst
@@ -139,7 +139,7 @@ When submitting a PR, please make sure that:
 3. The code is auto-formatted (``hatch fmt``).
 4. The build passes on your PR.
 
-To download, setup and perfom tests, run the following commands on Mac / Linux:
+To download, setup and perform tests, run the following commands on Mac / Linux:
 
 .. code-block:: console
 

diff --git a/mongomock/filtering.py b/mongomock/filtering.py
@@ -295,7 +295,7 @@ def _in_op(doc_val, search_val):
     doc_val = _force_list(doc_val)
     is_regex_list = [isinstance(x, _RE_TYPES) for x in search_val]
     if not any(is_regex_list):
-        return any(x in search_val for x in doc_val)
+        return any(x in search_val for x in doc_val) or doc_val in search_val
     for x, is_regex in zip(search_val, is_regex_list):
         if (is_regex and _regex(doc_val, x)) or (x in doc_val):
             return True

diff --git a/tests/test__mongomock.py b/tests/test__mongomock.py
@@ -643,6 +643,7 @@ def test__find_non_empty_array_field(self):
         self.cmp.compare.find({'array_field': [['abc']]})
         self.cmp.compare.find({'array_field': 'def'})
         self.cmp.compare.find({'array_field': ['def']})
+        self.cmp.compare.find({'array_field': {'$in': [['def'], [['abc']]]}})
 
     def test__find_by_objectid_in_list(self):
         # See #79