fix: Staking delegations should return empty list instead of rpc erro…

…r when no records found (#9423)

* return empty list instead of rpc error when no records found for staking delegations

* fix grpc query DelegatorDelegations tests

* remove response code tests for staking delegations

* fix failing tests

* change staking delegations response code to 200 in grpc test

* add staking delegations response code tests to TestQueryDelegatorDelegationsGRPC

* add address without delegations testcase

* add changes to grpc query tests of delegatorDelegations

* remove getRequest unused function from x/staking/client/rest/grpc_query_test.go

* minor fixes

* add testcases for request with no delegations

* address review comments

* add changelog

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

CHANGELOG.md

@@ -127,6 +127,7 @@ if input key is empty, or input data contains empty key.
 
 ### Improvements
 
+* (x/staking) [\#9423](https://github.com/cosmos/cosmos-sdk/pull/9423) Staking delegations now returns empty list instead of rpc error when no records found.
 * (baseapp, types) [#\9390](https://github.com/cosmos/cosmos-sdk/pull/9390) Add current block header hash to `Context`
 * (x/bank) [\#8614](https://github.com/cosmos/cosmos-sdk/issues/8614) Add `Name` and `Symbol` fields to denom metadata
 * (x/auth) [\#8522](https://github.com/cosmos/cosmos-sdk/pull/8522) Allow to query all stored accounts

x/staking/client/rest/grpc_query_test.go

@@ -4,8 +4,6 @@ package rest_test
 
 import (
 	"fmt"
-	"io/ioutil"
-	"net/http"
 	"testing"
 
 	"github.com/gogo/protobuf/proto"
@@ -414,39 +412,15 @@ func (s *IntegrationTestSuite) TestQueryUnbondingDelegationGRPC() {
 	}
 }
 
-func (s *IntegrationTestSuite) TestQueryDelegationsResponseCode() {
+func (s *IntegrationTestSuite) TestQueryDelegatorDelegationsGRPC() {
 	val := s.network.Validators[0]
+	baseURL := val.APIAddress
 
-	// Create new account in the keyring.
+	// Create new account in the keyring for address without delegations.
 	info, _, err := val.ClientCtx.Keyring.NewMnemonic("test", keyring.English, sdk.FullFundraiserPath, keyring.DefaultBIP39Passphrase, hd.Secp256k1)
 	s.Require().NoError(err)
 	newAddr := sdk.AccAddress(info.GetPubKey().Address())
 
-	s.T().Log("expect 404 error for address without delegations")
-	res, statusCode, err := getRequest(fmt.Sprintf("%s/cosmos/staking/v1beta1/delegations/%s", val.APIAddress, newAddr.String()))
-	s.Require().NoError(err)
-	s.Require().Contains(string(res), "\"code\": 5")
-	s.Require().Equal(404, statusCode)
-}
-
-func getRequest(url string) ([]byte, int, error) {
-	res, err := http.Get(url) // nolint:gosec
-	body, err := ioutil.ReadAll(res.Body)
-	if err != nil {
-		return nil, res.StatusCode, err
-	}
-
-	if err = res.Body.Close(); err != nil {
-		return nil, res.StatusCode, err
-	}
-
-	return body, res.StatusCode, nil
-}
-
-func (s *IntegrationTestSuite) TestQueryDelegatorDelegationsGRPC() {
-	val := s.network.Validators[0]
-	baseURL := val.APIAddress
-
 	testCases := []struct {
 		name         string
 		url          string
@@ -486,6 +460,19 @@ func (s *IntegrationTestSuite) TestQueryDelegatorDelegationsGRPC() {
 				Pagination: &query.PageResponse{Total: 1},
 			},
 		},
+		{
+			"address without delegations",
+			fmt.Sprintf("%s/cosmos/staking/v1beta1/delegations/%s", baseURL, newAddr.String()),
+			map[string]string{
+				grpctypes.GRPCBlockHeightHeader: "1",
+			},
+			false,
+			&types.QueryDelegatorDelegationsResponse{},
+			&types.QueryDelegatorDelegationsResponse{
+				DelegationResponses: types.DelegationResponses{},
+				Pagination:          &query.PageResponse{Total: 0},
+			},
+		},
 	}
 
 	for _, tc := range testCases {

x/staking/keeper/grpc_query.go

@@ -281,11 +281,6 @@ func (k Querier) DelegatorDelegations(c context.Context, req *types.QueryDelegat
 		return nil, status.Error(codes.Internal, err.Error())
 	}
 
-	if delegations == nil {
-		return nil, status.Errorf(
-			codes.NotFound,
-			"unable to find delegations for address %s", req.DelegatorAddr)
-	}
 	delegationResps, err := DelegationsToDelegationResponses(ctx, k.Keeper, delegations)
 	if err != nil {
 		return nil, status.Error(codes.Internal, err.Error())