S3:list_object_versions(): Fix delimiter to take prefix into account (#5562)

moto/s3/models.py

@@ -1631,10 +1631,12 @@ class S3Backend(BaseBackend, CloudWatchMetricProvider):
             # Filter for keys that start with prefix
             if not name.startswith(prefix):
                 continue
-            # separate out all keys that contain delimiter
-            if delimiter and delimiter in name:
-                index = name.index(delimiter) + len(delimiter)
-                prefix_including_delimiter = name[0:index]
+            # separate keys that contain the same string between the prefix and the first occurrence of the delimiter
+            if delimiter and delimiter in name[len(prefix) :]:
+                end_of_delimiter = (
+                    len(prefix) + name[len(prefix) :].index(delimiter) + len(delimiter)
+                )
+                prefix_including_delimiter = name[0:end_of_delimiter]
                 common_prefixes.append(prefix_including_delimiter)
                 continue
 

tests/test_s3/test_s3.py

@@ -2463,6 +2463,20 @@ def test_list_object_versions_with_delimiter():
         {"key11-without-data", "key12-without-data", "key13-without-data"}
     )
 
+    # Delimiter with Prefix being the entire key
+    response = s3.list_object_versions(
+        Bucket=bucket_name, Prefix="key1-with-data", Delimiter="-"
+    )
+    response.should.have.key("Versions").length_of(3)
+    response.shouldnt.have.key("CommonPrefixes")
+
+    # Delimiter without prefix
+    response = s3.list_object_versions(Bucket=bucket_name, Delimiter="-with-")
+    response["CommonPrefixes"].should.have.length_of(8)
+    response["CommonPrefixes"].should.contain({"Prefix": "key1-with-"})
+    # Should return all keys -without-data
+    response.should.have.key("Versions").length_of(24)
+
 
 @mock_s3
 def test_list_object_versions_with_delimiter_for_deleted_objects():