fix: float " " symbol in the preview_body (#32484)

Co-authored-by: Edward Zarecor <ezarecor@tcril.org>

lms/djangoapps/discussion/rest_api/serializers.py

@@ -427,10 +427,9 @@ class ThreadSerializer(_ContentSerializer):
 
     def get_preview_body(self, obj):
         """
-        Returns a cleaned and truncated version of the thread's body to display in a
-        preview capacity.
+        Returns a cleaned version of the thread's body to display in a preview capacity.
         """
-        return strip_tags(self.get_rendered_body(obj)).replace('\n', ' ')
+        return strip_tags(self.get_rendered_body(obj)).replace('\n', ' ').replace(' ', ' ')
 
     def get_close_reason(self, obj):
         """

lms/djangoapps/discussion/rest_api/tests/test_serializers.py

@@ -356,6 +356,21 @@ class ThreadSerializerSerializationTest(SerializerTestMixin, SharedModuleStoreTe
         })
         assert self.serialize(thread) == expected
 
+    def test_get_preview_body(self):
+        """
+        Test for the 'get_preview_body' method.
+
+        This test verifies that the 'get_preview_body' method returns a cleaned
+        version of the thread's body that is suitable for display as a preview.
+        The test specifically focuses on handling the presence of multiple
+        spaces within the body.
+        """
+        thread_data = self.make_cs_content(
+            {"body": "<p>This  is  a test thread body  with some text.</p>"}
+        )
+        serialized = self.serialize(thread_data)
+        assert serialized['preview_body'] == "This  is  a test thread body  with some text."
+
 
 @ddt.ddt
 class CommentSerializerTest(SerializerTestMixin, SharedModuleStoreTestCase):