fix: ballot sorting (#1851)

* fix: ballot sorting

* test sorting

x/oracle/types/ballot.go

@@ -114,7 +114,13 @@ func (pb ExchangeRateBallot) Len() int {
 // Less reports whether the element with
 // index i should sort before the element with index j.
 func (pb ExchangeRateBallot) Less(i, j int) bool {
-	return pb[i].ExchangeRate.LT(pb[j].ExchangeRate)
+	if pb[i].ExchangeRate.LT(pb[j].ExchangeRate) {
+		return true
+	}
+	if pb[i].ExchangeRate.Equal(pb[j].ExchangeRate) {
+		return bytes.Compare(pb[i].Voter, pb[j].Voter) < 0
+	}
+	return false
 }
 
 // Swap implements sort.Interface.

x/oracle/types/ballot_test.go

@@ -3,13 +3,15 @@ package types
 import (
 	"fmt"
 	"math"
+	"sort"
 	"strconv"
 	"testing"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/stretchr/testify/require"
 	"github.com/tendermint/tendermint/crypto/secp256k1"
 	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
+	"gotest.tools/v3/assert"
 )
 
 func TestToMap(t *testing.T) {
@@ -376,3 +378,29 @@ func TestClaimMapToSlice(t *testing.T) {
 	})
 	require.Equal(t, []Claim{claim, claim}, claimSlice)
 }
+
+func TestExchangeRateBallotSort(t *testing.T) {
+	v1 := VoteForTally{ExchangeRate: sdk.MustNewDecFromStr("0.2"), Voter: sdk.ValAddress{0, 1}}
+	v1Cpy := VoteForTally{ExchangeRate: sdk.MustNewDecFromStr("0.2"), Voter: sdk.ValAddress{0, 1}}
+	v2 := VoteForTally{ExchangeRate: sdk.MustNewDecFromStr("0.1"), Voter: sdk.ValAddress{0, 1, 1}}
+	v3 := VoteForTally{ExchangeRate: sdk.MustNewDecFromStr("0.1"), Voter: sdk.ValAddress{0, 1}}
+	v4 := VoteForTally{ExchangeRate: sdk.MustNewDecFromStr("0.5"), Voter: sdk.ValAddress{1}}
+
+	tcs := []struct {
+		got      ExchangeRateBallot
+		expected ExchangeRateBallot
+	}{
+		{got: ExchangeRateBallot{v1, v2, v3, v4},
+			expected: ExchangeRateBallot{v3, v2, v1, v4}},
+		{got: ExchangeRateBallot{v1},
+			expected: ExchangeRateBallot{v1}},
+		{got: ExchangeRateBallot{v1, v1Cpy},
+			expected: ExchangeRateBallot{v1, v1Cpy}},
+	}
+	for i, tc := range tcs {
+		t.Run(fmt.Sprint(i), func(t *testing.T) {
+			sort.Sort(tc.got)
+			assert.DeepEqual(t, tc.expected, tc.got)
+		})
+	}
+}