/eth/v1/config/deposit_contract return string instead of uint (#12952)

* Convert uint to string

* Add test

* Rename test

beacon-chain/rpc/eth/beacon/handlers.go

@@ -746,10 +746,10 @@ func (*Server) GetDepositContract(w http.ResponseWriter, r *http.Request) {
 
 	http2.WriteJson(w, &DepositContractResponse{
 		Data: &struct {
-			ChainId uint64 `json:"chain_id"`
+			ChainId string `json:"chain_id"`
 			Address string `json:"address"`
 		}{
-			ChainId: params.BeaconConfig().DepositChainID,
+			ChainId: strconv.FormatUint(params.BeaconConfig().DepositChainID, 10),
 			Address: params.BeaconConfig().DepositContractAddress,
 		},
 	})

beacon-chain/rpc/eth/beacon/handlers_test.go

@@ -1654,3 +1654,23 @@ func TestGetGenesis(t *testing.T) {
 		assert.StringContains(t, "Chain genesis info is not yet known", e.Message)
 	})
 }
+
+func TestGetDepositContract(t *testing.T) {
+	params.SetupTestConfigCleanup(t)
+	config := params.BeaconConfig().Copy()
+	config.DepositChainID = uint64(10)
+	config.DepositContractAddress = "0x4242424242424242424242424242424242424242"
+	params.OverrideBeaconConfig(config)
+
+	request := httptest.NewRequest(http.MethodGet, "/eth/v1/beacon/states/{state_id}/finality_checkpoints", nil)
+	writer := httptest.NewRecorder()
+	writer.Body = &bytes.Buffer{}
+
+	s := &Server{}
+	s.GetDepositContract(writer, request)
+	assert.Equal(t, http.StatusOK, writer.Code)
+	response := DepositContractResponse{}
+	require.NoError(t, json.Unmarshal(writer.Body.Bytes(), &response))
+	assert.Equal(t, "10", response.Data.ChainId)
+	assert.Equal(t, "0x4242424242424242424242424242424242424242", response.Data.Address)
+}

beacon-chain/rpc/eth/beacon/structs.go

@@ -20,7 +20,7 @@ type GetCommitteesResponse struct {
 
 type DepositContractResponse struct {
 	Data *struct {
-		ChainId uint64 `json:"chain_id"`
+		ChainId string `json:"chain_id"`
 		Address string `json:"address"`
 	} `json:"data"`
 }