Add test for fetching duplicate indices

Author: danyalprout

api/service/api.go

@@ -218,14 +218,14 @@ func filterBlobs(blobs []*deneb.BlobSidecar, indices string) ([]*deneb.BlobSidec
 		return blobs, nil
 	}
 
-	indicesMap := map[deneb.BlobIndex]bool{}
+	indicesMap := map[deneb.BlobIndex]struct{}{}
 	for _, index := range splits {
 		parsedInt, err := strconv.ParseUint(index, 10, 64)
 		if err != nil {
 			return nil, newIndicesError(index)
 		}
 		blobIndex := deneb.BlobIndex(parsedInt)
-		indicesMap[blobIndex] = true
+		indicesMap[blobIndex] = struct{}{}
 	}
 
 	filteredBlobs := make([]*deneb.BlobSidecar, 0)

api/service/api_test.go

@@ -162,6 +162,16 @@ func TestAPIService(t *testing.T) {
 				},
 			},
 		},
+		{
+			name:   "deduplicates indices",
+			path:   "/eth/v1/beacon/blob_sidecars/1234?indices=1,1,1",
+			status: 200,
+			expected: &storage.BlobSidecars{
+				Data: []*deneb.BlobSidecar{
+					blockTwo.BlobSidecars.Data[1],
+				},
+			},
+		},
 		{
 			name:   "indices out of bounds returns empty array",
 			path:   "/eth/v1/beacon/blob_sidecars/1234?indices=3",