add Equals for aggAlgorithm

return nil for empty list when do median

x/oracle/keeper/feedermanagement/aggregator.go

@@ -35,13 +35,19 @@ func (a *aggregator) Equals(a2 *aggregator) bool {
 	if !a.t.Equals(a2.t) {
 		return false
 	}
+
 	if !a.v.Equals(a2.v) {
 		return false
 	}
+
 	if !a.ds.Equals(a2.ds) {
 		return false
 	}
 
+	if !a.algo.Equals(a2.algo) {
+		return false
+	}
+
 	return true
 }
 

x/oracle/keeper/feedermanagement/algo.go

@@ -6,6 +6,12 @@ import (
 	"strings"
 )
 
+type AlgoType string
+
+const (
+	AlgoMedian AlgoType = "median"
+)
+
 type BigIntList []*big.Int
 
 func (b BigIntList) Len() int {
@@ -21,6 +27,9 @@ func (b BigIntList) Swap(i, j int) {
 }
 
 func (b BigIntList) Median() *big.Int {
+	if len(b) == 0 {
+		return nil
+	}
 	sort.Sort(b)
 	l := len(b)
 	if l%2 == 1 {
@@ -33,6 +42,8 @@ type AggAlgorithm interface {
 	Add(*PriceResult) bool
 	GetResult() *PriceResult
 	Reset()
+	Type() AlgoType
+	Equals(AggAlgorithm) bool
 }
 
 type priceType int
@@ -105,6 +116,7 @@ func (a *AggMedian) GetResult() *PriceResult {
 		return nil
 	}
 	if a.t == number {
+		// when a.t is set to number, the length of a.list must be bigger than 0, so the Median() must return a non-nil result
 		result := BigIntList(a.list).Median().String()
 		decimal := a.decimal
 		return &PriceResult{
@@ -128,5 +140,13 @@ func (a *AggMedian) Reset() {
 	a.finalString = ""
 }
 
+func (a *AggMedian) Type() AlgoType {
+	return AlgoMedian
+}
+
+func (a *AggMedian) Equals(a2 AggAlgorithm) bool {
+	return a.Type() == a2.Type()
+}
+
 //nolint:unused
 var defaultAggMedian = NewAggMedian()